Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/mm/swapfile.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * Swap reorganised 29.12.95, Stephen Tweedie | |
6 | */ | |
7 | ||
1da177e4 | 8 | #include <linux/mm.h> |
6e84f315 | 9 | #include <linux/sched/mm.h> |
29930025 | 10 | #include <linux/sched/task.h> |
1da177e4 LT |
11 | #include <linux/hugetlb.h> |
12 | #include <linux/mman.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/kernel_stat.h> | |
15 | #include <linux/swap.h> | |
16 | #include <linux/vmalloc.h> | |
17 | #include <linux/pagemap.h> | |
18 | #include <linux/namei.h> | |
072441e2 | 19 | #include <linux/shmem_fs.h> |
1da177e4 | 20 | #include <linux/blkdev.h> |
20137a49 | 21 | #include <linux/random.h> |
1da177e4 LT |
22 | #include <linux/writeback.h> |
23 | #include <linux/proc_fs.h> | |
24 | #include <linux/seq_file.h> | |
25 | #include <linux/init.h> | |
5ad64688 | 26 | #include <linux/ksm.h> |
1da177e4 LT |
27 | #include <linux/rmap.h> |
28 | #include <linux/security.h> | |
29 | #include <linux/backing-dev.h> | |
fc0abb14 | 30 | #include <linux/mutex.h> |
c59ede7b | 31 | #include <linux/capability.h> |
1da177e4 | 32 | #include <linux/syscalls.h> |
8a9f3ccd | 33 | #include <linux/memcontrol.h> |
66d7dd51 | 34 | #include <linux/poll.h> |
72788c38 | 35 | #include <linux/oom.h> |
38b5faf4 DM |
36 | #include <linux/frontswap.h> |
37 | #include <linux/swapfile.h> | |
f981c595 | 38 | #include <linux/export.h> |
67afa38e | 39 | #include <linux/swap_slots.h> |
155b5f88 | 40 | #include <linux/sort.h> |
1da177e4 LT |
41 | |
42 | #include <asm/pgtable.h> | |
43 | #include <asm/tlbflush.h> | |
44 | #include <linux/swapops.h> | |
5d1ea48b | 45 | #include <linux/swap_cgroup.h> |
1da177e4 | 46 | |
570a335b HD |
47 | static bool swap_count_continued(struct swap_info_struct *, pgoff_t, |
48 | unsigned char); | |
49 | static void free_swap_count_continuations(struct swap_info_struct *); | |
d4906e1a | 50 | static sector_t map_swap_entry(swp_entry_t, struct block_device**); |
570a335b | 51 | |
38b5faf4 | 52 | DEFINE_SPINLOCK(swap_lock); |
7c363b8c | 53 | static unsigned int nr_swapfiles; |
ec8acf20 | 54 | atomic_long_t nr_swap_pages; |
fb0fec50 CW |
55 | /* |
56 | * Some modules use swappable objects and may try to swap them out under | |
57 | * memory pressure (via the shrinker). Before doing so, they may wish to | |
58 | * check to see if any swap space is available. | |
59 | */ | |
60 | EXPORT_SYMBOL_GPL(nr_swap_pages); | |
ec8acf20 | 61 | /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */ |
1da177e4 | 62 | long total_swap_pages; |
a2468cc9 | 63 | static int least_priority = -1; |
1da177e4 | 64 | |
1da177e4 LT |
65 | static const char Bad_file[] = "Bad swap file entry "; |
66 | static const char Unused_file[] = "Unused swap file entry "; | |
67 | static const char Bad_offset[] = "Bad swap offset entry "; | |
68 | static const char Unused_offset[] = "Unused swap offset entry "; | |
69 | ||
adfab836 DS |
70 | /* |
71 | * all active swap_info_structs | |
72 | * protected with swap_lock, and ordered by priority. | |
73 | */ | |
18ab4d4c DS |
74 | PLIST_HEAD(swap_active_head); |
75 | ||
76 | /* | |
77 | * all available (active, not full) swap_info_structs | |
78 | * protected with swap_avail_lock, ordered by priority. | |
79 | * This is used by get_swap_page() instead of swap_active_head | |
80 | * because swap_active_head includes all swap_info_structs, | |
81 | * but get_swap_page() doesn't need to look at full ones. | |
82 | * This uses its own lock instead of swap_lock because when a | |
83 | * swap_info_struct changes between not-full/full, it needs to | |
84 | * add/remove itself to/from this list, but the swap_info_struct->lock | |
85 | * is held and the locking order requires swap_lock to be taken | |
86 | * before any swap_info_struct->lock. | |
87 | */ | |
a2468cc9 | 88 | struct plist_head *swap_avail_heads; |
18ab4d4c | 89 | static DEFINE_SPINLOCK(swap_avail_lock); |
1da177e4 | 90 | |
38b5faf4 | 91 | struct swap_info_struct *swap_info[MAX_SWAPFILES]; |
1da177e4 | 92 | |
fc0abb14 | 93 | static DEFINE_MUTEX(swapon_mutex); |
1da177e4 | 94 | |
66d7dd51 KS |
95 | static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait); |
96 | /* Activity counter to indicate that a swapon or swapoff has occurred */ | |
97 | static atomic_t proc_poll_event = ATOMIC_INIT(0); | |
98 | ||
81a0298b HY |
99 | atomic_t nr_rotate_swap = ATOMIC_INIT(0); |
100 | ||
8d69aaee | 101 | static inline unsigned char swap_count(unsigned char ent) |
355cfa73 | 102 | { |
570a335b | 103 | return ent & ~SWAP_HAS_CACHE; /* may include SWAP_HAS_CONT flag */ |
355cfa73 KH |
104 | } |
105 | ||
efa90a98 | 106 | /* returns 1 if swap entry is freed */ |
c9e44410 KH |
107 | static int |
108 | __try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset) | |
109 | { | |
efa90a98 | 110 | swp_entry_t entry = swp_entry(si->type, offset); |
c9e44410 KH |
111 | struct page *page; |
112 | int ret = 0; | |
113 | ||
f6ab1f7f | 114 | page = find_get_page(swap_address_space(entry), swp_offset(entry)); |
c9e44410 KH |
115 | if (!page) |
116 | return 0; | |
117 | /* | |
118 | * This function is called from scan_swap_map() and it's called | |
119 | * by vmscan.c at reclaiming pages. So, we hold a lock on a page, here. | |
120 | * We have to use trylock for avoiding deadlock. This is a special | |
121 | * case and you should use try_to_free_swap() with explicit lock_page() | |
122 | * in usual operations. | |
123 | */ | |
124 | if (trylock_page(page)) { | |
125 | ret = try_to_free_swap(page); | |
126 | unlock_page(page); | |
127 | } | |
09cbfeaf | 128 | put_page(page); |
c9e44410 KH |
129 | return ret; |
130 | } | |
355cfa73 | 131 | |
6a6ba831 HD |
132 | /* |
133 | * swapon tell device that all the old swap contents can be discarded, | |
134 | * to allow the swap device to optimize its wear-levelling. | |
135 | */ | |
136 | static int discard_swap(struct swap_info_struct *si) | |
137 | { | |
138 | struct swap_extent *se; | |
9625a5f2 HD |
139 | sector_t start_block; |
140 | sector_t nr_blocks; | |
6a6ba831 HD |
141 | int err = 0; |
142 | ||
9625a5f2 HD |
143 | /* Do not discard the swap header page! */ |
144 | se = &si->first_swap_extent; | |
145 | start_block = (se->start_block + 1) << (PAGE_SHIFT - 9); | |
146 | nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9); | |
147 | if (nr_blocks) { | |
148 | err = blkdev_issue_discard(si->bdev, start_block, | |
dd3932ed | 149 | nr_blocks, GFP_KERNEL, 0); |
9625a5f2 HD |
150 | if (err) |
151 | return err; | |
152 | cond_resched(); | |
153 | } | |
6a6ba831 | 154 | |
9625a5f2 HD |
155 | list_for_each_entry(se, &si->first_swap_extent.list, list) { |
156 | start_block = se->start_block << (PAGE_SHIFT - 9); | |
157 | nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); | |
6a6ba831 HD |
158 | |
159 | err = blkdev_issue_discard(si->bdev, start_block, | |
dd3932ed | 160 | nr_blocks, GFP_KERNEL, 0); |
6a6ba831 HD |
161 | if (err) |
162 | break; | |
163 | ||
164 | cond_resched(); | |
165 | } | |
166 | return err; /* That will often be -EOPNOTSUPP */ | |
167 | } | |
168 | ||
7992fde7 HD |
169 | /* |
170 | * swap allocation tell device that a cluster of swap can now be discarded, | |
171 | * to allow the swap device to optimize its wear-levelling. | |
172 | */ | |
173 | static void discard_swap_cluster(struct swap_info_struct *si, | |
174 | pgoff_t start_page, pgoff_t nr_pages) | |
175 | { | |
176 | struct swap_extent *se = si->curr_swap_extent; | |
177 | int found_extent = 0; | |
178 | ||
179 | while (nr_pages) { | |
7992fde7 HD |
180 | if (se->start_page <= start_page && |
181 | start_page < se->start_page + se->nr_pages) { | |
182 | pgoff_t offset = start_page - se->start_page; | |
183 | sector_t start_block = se->start_block + offset; | |
858a2990 | 184 | sector_t nr_blocks = se->nr_pages - offset; |
7992fde7 HD |
185 | |
186 | if (nr_blocks > nr_pages) | |
187 | nr_blocks = nr_pages; | |
188 | start_page += nr_blocks; | |
189 | nr_pages -= nr_blocks; | |
190 | ||
191 | if (!found_extent++) | |
192 | si->curr_swap_extent = se; | |
193 | ||
194 | start_block <<= PAGE_SHIFT - 9; | |
195 | nr_blocks <<= PAGE_SHIFT - 9; | |
196 | if (blkdev_issue_discard(si->bdev, start_block, | |
dd3932ed | 197 | nr_blocks, GFP_NOIO, 0)) |
7992fde7 HD |
198 | break; |
199 | } | |
200 | ||
a8ae4991 | 201 | se = list_next_entry(se, list); |
7992fde7 HD |
202 | } |
203 | } | |
204 | ||
38d8b4e6 HY |
205 | #ifdef CONFIG_THP_SWAP |
206 | #define SWAPFILE_CLUSTER HPAGE_PMD_NR | |
207 | #else | |
048c27fd | 208 | #define SWAPFILE_CLUSTER 256 |
38d8b4e6 | 209 | #endif |
048c27fd HD |
210 | #define LATENCY_LIMIT 256 |
211 | ||
2a8f9449 SL |
212 | static inline void cluster_set_flag(struct swap_cluster_info *info, |
213 | unsigned int flag) | |
214 | { | |
215 | info->flags = flag; | |
216 | } | |
217 | ||
218 | static inline unsigned int cluster_count(struct swap_cluster_info *info) | |
219 | { | |
220 | return info->data; | |
221 | } | |
222 | ||
223 | static inline void cluster_set_count(struct swap_cluster_info *info, | |
224 | unsigned int c) | |
225 | { | |
226 | info->data = c; | |
227 | } | |
228 | ||
229 | static inline void cluster_set_count_flag(struct swap_cluster_info *info, | |
230 | unsigned int c, unsigned int f) | |
231 | { | |
232 | info->flags = f; | |
233 | info->data = c; | |
234 | } | |
235 | ||
236 | static inline unsigned int cluster_next(struct swap_cluster_info *info) | |
237 | { | |
238 | return info->data; | |
239 | } | |
240 | ||
241 | static inline void cluster_set_next(struct swap_cluster_info *info, | |
242 | unsigned int n) | |
243 | { | |
244 | info->data = n; | |
245 | } | |
246 | ||
247 | static inline void cluster_set_next_flag(struct swap_cluster_info *info, | |
248 | unsigned int n, unsigned int f) | |
249 | { | |
250 | info->flags = f; | |
251 | info->data = n; | |
252 | } | |
253 | ||
254 | static inline bool cluster_is_free(struct swap_cluster_info *info) | |
255 | { | |
256 | return info->flags & CLUSTER_FLAG_FREE; | |
257 | } | |
258 | ||
259 | static inline bool cluster_is_null(struct swap_cluster_info *info) | |
260 | { | |
261 | return info->flags & CLUSTER_FLAG_NEXT_NULL; | |
262 | } | |
263 | ||
264 | static inline void cluster_set_null(struct swap_cluster_info *info) | |
265 | { | |
266 | info->flags = CLUSTER_FLAG_NEXT_NULL; | |
267 | info->data = 0; | |
268 | } | |
269 | ||
e0709829 HY |
270 | static inline bool cluster_is_huge(struct swap_cluster_info *info) |
271 | { | |
272 | return info->flags & CLUSTER_FLAG_HUGE; | |
273 | } | |
274 | ||
275 | static inline void cluster_clear_huge(struct swap_cluster_info *info) | |
276 | { | |
277 | info->flags &= ~CLUSTER_FLAG_HUGE; | |
278 | } | |
279 | ||
235b6217 HY |
280 | static inline struct swap_cluster_info *lock_cluster(struct swap_info_struct *si, |
281 | unsigned long offset) | |
282 | { | |
283 | struct swap_cluster_info *ci; | |
284 | ||
285 | ci = si->cluster_info; | |
286 | if (ci) { | |
287 | ci += offset / SWAPFILE_CLUSTER; | |
288 | spin_lock(&ci->lock); | |
289 | } | |
290 | return ci; | |
291 | } | |
292 | ||
293 | static inline void unlock_cluster(struct swap_cluster_info *ci) | |
294 | { | |
295 | if (ci) | |
296 | spin_unlock(&ci->lock); | |
297 | } | |
298 | ||
299 | static inline struct swap_cluster_info *lock_cluster_or_swap_info( | |
300 | struct swap_info_struct *si, | |
301 | unsigned long offset) | |
302 | { | |
303 | struct swap_cluster_info *ci; | |
304 | ||
305 | ci = lock_cluster(si, offset); | |
306 | if (!ci) | |
307 | spin_lock(&si->lock); | |
308 | ||
309 | return ci; | |
310 | } | |
311 | ||
312 | static inline void unlock_cluster_or_swap_info(struct swap_info_struct *si, | |
313 | struct swap_cluster_info *ci) | |
314 | { | |
315 | if (ci) | |
316 | unlock_cluster(ci); | |
317 | else | |
318 | spin_unlock(&si->lock); | |
319 | } | |
320 | ||
6b534915 HY |
321 | static inline bool cluster_list_empty(struct swap_cluster_list *list) |
322 | { | |
323 | return cluster_is_null(&list->head); | |
324 | } | |
325 | ||
326 | static inline unsigned int cluster_list_first(struct swap_cluster_list *list) | |
327 | { | |
328 | return cluster_next(&list->head); | |
329 | } | |
330 | ||
331 | static void cluster_list_init(struct swap_cluster_list *list) | |
332 | { | |
333 | cluster_set_null(&list->head); | |
334 | cluster_set_null(&list->tail); | |
335 | } | |
336 | ||
337 | static void cluster_list_add_tail(struct swap_cluster_list *list, | |
338 | struct swap_cluster_info *ci, | |
339 | unsigned int idx) | |
340 | { | |
341 | if (cluster_list_empty(list)) { | |
342 | cluster_set_next_flag(&list->head, idx, 0); | |
343 | cluster_set_next_flag(&list->tail, idx, 0); | |
344 | } else { | |
235b6217 | 345 | struct swap_cluster_info *ci_tail; |
6b534915 HY |
346 | unsigned int tail = cluster_next(&list->tail); |
347 | ||
235b6217 HY |
348 | /* |
349 | * Nested cluster lock, but both cluster locks are | |
350 | * only acquired when we held swap_info_struct->lock | |
351 | */ | |
352 | ci_tail = ci + tail; | |
353 | spin_lock_nested(&ci_tail->lock, SINGLE_DEPTH_NESTING); | |
354 | cluster_set_next(ci_tail, idx); | |
0ef017d1 | 355 | spin_unlock(&ci_tail->lock); |
6b534915 HY |
356 | cluster_set_next_flag(&list->tail, idx, 0); |
357 | } | |
358 | } | |
359 | ||
360 | static unsigned int cluster_list_del_first(struct swap_cluster_list *list, | |
361 | struct swap_cluster_info *ci) | |
362 | { | |
363 | unsigned int idx; | |
364 | ||
365 | idx = cluster_next(&list->head); | |
366 | if (cluster_next(&list->tail) == idx) { | |
367 | cluster_set_null(&list->head); | |
368 | cluster_set_null(&list->tail); | |
369 | } else | |
370 | cluster_set_next_flag(&list->head, | |
371 | cluster_next(&ci[idx]), 0); | |
372 | ||
373 | return idx; | |
374 | } | |
375 | ||
815c2c54 SL |
376 | /* Add a cluster to discard list and schedule it to do discard */ |
377 | static void swap_cluster_schedule_discard(struct swap_info_struct *si, | |
378 | unsigned int idx) | |
379 | { | |
380 | /* | |
381 | * If scan_swap_map() can't find a free cluster, it will check | |
382 | * si->swap_map directly. To make sure the discarding cluster isn't | |
383 | * taken by scan_swap_map(), mark the swap entries bad (occupied). It | |
384 | * will be cleared after discard | |
385 | */ | |
386 | memset(si->swap_map + idx * SWAPFILE_CLUSTER, | |
387 | SWAP_MAP_BAD, SWAPFILE_CLUSTER); | |
388 | ||
6b534915 | 389 | cluster_list_add_tail(&si->discard_clusters, si->cluster_info, idx); |
815c2c54 SL |
390 | |
391 | schedule_work(&si->discard_work); | |
392 | } | |
393 | ||
38d8b4e6 HY |
394 | static void __free_cluster(struct swap_info_struct *si, unsigned long idx) |
395 | { | |
396 | struct swap_cluster_info *ci = si->cluster_info; | |
397 | ||
398 | cluster_set_flag(ci + idx, CLUSTER_FLAG_FREE); | |
399 | cluster_list_add_tail(&si->free_clusters, ci, idx); | |
400 | } | |
401 | ||
815c2c54 SL |
402 | /* |
403 | * Doing discard actually. After a cluster discard is finished, the cluster | |
404 | * will be added to free cluster list. caller should hold si->lock. | |
405 | */ | |
406 | static void swap_do_scheduled_discard(struct swap_info_struct *si) | |
407 | { | |
235b6217 | 408 | struct swap_cluster_info *info, *ci; |
815c2c54 SL |
409 | unsigned int idx; |
410 | ||
411 | info = si->cluster_info; | |
412 | ||
6b534915 HY |
413 | while (!cluster_list_empty(&si->discard_clusters)) { |
414 | idx = cluster_list_del_first(&si->discard_clusters, info); | |
815c2c54 SL |
415 | spin_unlock(&si->lock); |
416 | ||
417 | discard_swap_cluster(si, idx * SWAPFILE_CLUSTER, | |
418 | SWAPFILE_CLUSTER); | |
419 | ||
420 | spin_lock(&si->lock); | |
235b6217 | 421 | ci = lock_cluster(si, idx * SWAPFILE_CLUSTER); |
38d8b4e6 | 422 | __free_cluster(si, idx); |
815c2c54 SL |
423 | memset(si->swap_map + idx * SWAPFILE_CLUSTER, |
424 | 0, SWAPFILE_CLUSTER); | |
235b6217 | 425 | unlock_cluster(ci); |
815c2c54 SL |
426 | } |
427 | } | |
428 | ||
429 | static void swap_discard_work(struct work_struct *work) | |
430 | { | |
431 | struct swap_info_struct *si; | |
432 | ||
433 | si = container_of(work, struct swap_info_struct, discard_work); | |
434 | ||
435 | spin_lock(&si->lock); | |
436 | swap_do_scheduled_discard(si); | |
437 | spin_unlock(&si->lock); | |
438 | } | |
439 | ||
38d8b4e6 HY |
440 | static void alloc_cluster(struct swap_info_struct *si, unsigned long idx) |
441 | { | |
442 | struct swap_cluster_info *ci = si->cluster_info; | |
443 | ||
444 | VM_BUG_ON(cluster_list_first(&si->free_clusters) != idx); | |
445 | cluster_list_del_first(&si->free_clusters, ci); | |
446 | cluster_set_count_flag(ci + idx, 0, 0); | |
447 | } | |
448 | ||
449 | static void free_cluster(struct swap_info_struct *si, unsigned long idx) | |
450 | { | |
451 | struct swap_cluster_info *ci = si->cluster_info + idx; | |
452 | ||
453 | VM_BUG_ON(cluster_count(ci) != 0); | |
454 | /* | |
455 | * If the swap is discardable, prepare discard the cluster | |
456 | * instead of free it immediately. The cluster will be freed | |
457 | * after discard. | |
458 | */ | |
459 | if ((si->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == | |
460 | (SWP_WRITEOK | SWP_PAGE_DISCARD)) { | |
461 | swap_cluster_schedule_discard(si, idx); | |
462 | return; | |
463 | } | |
464 | ||
465 | __free_cluster(si, idx); | |
466 | } | |
467 | ||
2a8f9449 SL |
468 | /* |
469 | * The cluster corresponding to page_nr will be used. The cluster will be | |
470 | * removed from free cluster list and its usage counter will be increased. | |
471 | */ | |
472 | static void inc_cluster_info_page(struct swap_info_struct *p, | |
473 | struct swap_cluster_info *cluster_info, unsigned long page_nr) | |
474 | { | |
475 | unsigned long idx = page_nr / SWAPFILE_CLUSTER; | |
476 | ||
477 | if (!cluster_info) | |
478 | return; | |
38d8b4e6 HY |
479 | if (cluster_is_free(&cluster_info[idx])) |
480 | alloc_cluster(p, idx); | |
2a8f9449 SL |
481 | |
482 | VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER); | |
483 | cluster_set_count(&cluster_info[idx], | |
484 | cluster_count(&cluster_info[idx]) + 1); | |
485 | } | |
486 | ||
487 | /* | |
488 | * The cluster corresponding to page_nr decreases one usage. If the usage | |
489 | * counter becomes 0, which means no page in the cluster is in using, we can | |
490 | * optionally discard the cluster and add it to free cluster list. | |
491 | */ | |
492 | static void dec_cluster_info_page(struct swap_info_struct *p, | |
493 | struct swap_cluster_info *cluster_info, unsigned long page_nr) | |
494 | { | |
495 | unsigned long idx = page_nr / SWAPFILE_CLUSTER; | |
496 | ||
497 | if (!cluster_info) | |
498 | return; | |
499 | ||
500 | VM_BUG_ON(cluster_count(&cluster_info[idx]) == 0); | |
501 | cluster_set_count(&cluster_info[idx], | |
502 | cluster_count(&cluster_info[idx]) - 1); | |
503 | ||
38d8b4e6 HY |
504 | if (cluster_count(&cluster_info[idx]) == 0) |
505 | free_cluster(p, idx); | |
2a8f9449 SL |
506 | } |
507 | ||
508 | /* | |
509 | * It's possible scan_swap_map() uses a free cluster in the middle of free | |
510 | * cluster list. Avoiding such abuse to avoid list corruption. | |
511 | */ | |
ebc2a1a6 SL |
512 | static bool |
513 | scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si, | |
2a8f9449 SL |
514 | unsigned long offset) |
515 | { | |
ebc2a1a6 SL |
516 | struct percpu_cluster *percpu_cluster; |
517 | bool conflict; | |
518 | ||
2a8f9449 | 519 | offset /= SWAPFILE_CLUSTER; |
6b534915 HY |
520 | conflict = !cluster_list_empty(&si->free_clusters) && |
521 | offset != cluster_list_first(&si->free_clusters) && | |
2a8f9449 | 522 | cluster_is_free(&si->cluster_info[offset]); |
ebc2a1a6 SL |
523 | |
524 | if (!conflict) | |
525 | return false; | |
526 | ||
527 | percpu_cluster = this_cpu_ptr(si->percpu_cluster); | |
528 | cluster_set_null(&percpu_cluster->index); | |
529 | return true; | |
530 | } | |
531 | ||
532 | /* | |
533 | * Try to get a swap entry from current cpu's swap entry pool (a cluster). This | |
534 | * might involve allocating a new cluster for current CPU too. | |
535 | */ | |
36005bae | 536 | static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, |
ebc2a1a6 SL |
537 | unsigned long *offset, unsigned long *scan_base) |
538 | { | |
539 | struct percpu_cluster *cluster; | |
235b6217 | 540 | struct swap_cluster_info *ci; |
ebc2a1a6 | 541 | bool found_free; |
235b6217 | 542 | unsigned long tmp, max; |
ebc2a1a6 SL |
543 | |
544 | new_cluster: | |
545 | cluster = this_cpu_ptr(si->percpu_cluster); | |
546 | if (cluster_is_null(&cluster->index)) { | |
6b534915 HY |
547 | if (!cluster_list_empty(&si->free_clusters)) { |
548 | cluster->index = si->free_clusters.head; | |
ebc2a1a6 SL |
549 | cluster->next = cluster_next(&cluster->index) * |
550 | SWAPFILE_CLUSTER; | |
6b534915 | 551 | } else if (!cluster_list_empty(&si->discard_clusters)) { |
ebc2a1a6 SL |
552 | /* |
553 | * we don't have free cluster but have some clusters in | |
554 | * discarding, do discard now and reclaim them | |
555 | */ | |
556 | swap_do_scheduled_discard(si); | |
557 | *scan_base = *offset = si->cluster_next; | |
558 | goto new_cluster; | |
559 | } else | |
36005bae | 560 | return false; |
ebc2a1a6 SL |
561 | } |
562 | ||
563 | found_free = false; | |
564 | ||
565 | /* | |
566 | * Other CPUs can use our cluster if they can't find a free cluster, | |
567 | * check if there is still free entry in the cluster | |
568 | */ | |
569 | tmp = cluster->next; | |
235b6217 HY |
570 | max = min_t(unsigned long, si->max, |
571 | (cluster_next(&cluster->index) + 1) * SWAPFILE_CLUSTER); | |
572 | if (tmp >= max) { | |
573 | cluster_set_null(&cluster->index); | |
574 | goto new_cluster; | |
575 | } | |
576 | ci = lock_cluster(si, tmp); | |
577 | while (tmp < max) { | |
ebc2a1a6 SL |
578 | if (!si->swap_map[tmp]) { |
579 | found_free = true; | |
580 | break; | |
581 | } | |
582 | tmp++; | |
583 | } | |
235b6217 | 584 | unlock_cluster(ci); |
ebc2a1a6 SL |
585 | if (!found_free) { |
586 | cluster_set_null(&cluster->index); | |
587 | goto new_cluster; | |
588 | } | |
589 | cluster->next = tmp + 1; | |
590 | *offset = tmp; | |
591 | *scan_base = tmp; | |
36005bae | 592 | return found_free; |
2a8f9449 SL |
593 | } |
594 | ||
a2468cc9 AL |
595 | static void __del_from_avail_list(struct swap_info_struct *p) |
596 | { | |
597 | int nid; | |
598 | ||
599 | for_each_node(nid) | |
600 | plist_del(&p->avail_lists[nid], &swap_avail_heads[nid]); | |
601 | } | |
602 | ||
603 | static void del_from_avail_list(struct swap_info_struct *p) | |
604 | { | |
605 | spin_lock(&swap_avail_lock); | |
606 | __del_from_avail_list(p); | |
607 | spin_unlock(&swap_avail_lock); | |
608 | } | |
609 | ||
38d8b4e6 HY |
610 | static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset, |
611 | unsigned int nr_entries) | |
612 | { | |
613 | unsigned int end = offset + nr_entries - 1; | |
614 | ||
615 | if (offset == si->lowest_bit) | |
616 | si->lowest_bit += nr_entries; | |
617 | if (end == si->highest_bit) | |
618 | si->highest_bit -= nr_entries; | |
619 | si->inuse_pages += nr_entries; | |
620 | if (si->inuse_pages == si->pages) { | |
621 | si->lowest_bit = si->max; | |
622 | si->highest_bit = 0; | |
a2468cc9 | 623 | del_from_avail_list(si); |
38d8b4e6 HY |
624 | } |
625 | } | |
626 | ||
a2468cc9 AL |
627 | static void add_to_avail_list(struct swap_info_struct *p) |
628 | { | |
629 | int nid; | |
630 | ||
631 | spin_lock(&swap_avail_lock); | |
632 | for_each_node(nid) { | |
633 | WARN_ON(!plist_node_empty(&p->avail_lists[nid])); | |
634 | plist_add(&p->avail_lists[nid], &swap_avail_heads[nid]); | |
635 | } | |
636 | spin_unlock(&swap_avail_lock); | |
637 | } | |
638 | ||
38d8b4e6 HY |
639 | static void swap_range_free(struct swap_info_struct *si, unsigned long offset, |
640 | unsigned int nr_entries) | |
641 | { | |
642 | unsigned long end = offset + nr_entries - 1; | |
643 | void (*swap_slot_free_notify)(struct block_device *, unsigned long); | |
644 | ||
645 | if (offset < si->lowest_bit) | |
646 | si->lowest_bit = offset; | |
647 | if (end > si->highest_bit) { | |
648 | bool was_full = !si->highest_bit; | |
649 | ||
650 | si->highest_bit = end; | |
a2468cc9 AL |
651 | if (was_full && (si->flags & SWP_WRITEOK)) |
652 | add_to_avail_list(si); | |
38d8b4e6 HY |
653 | } |
654 | atomic_long_add(nr_entries, &nr_swap_pages); | |
655 | si->inuse_pages -= nr_entries; | |
656 | if (si->flags & SWP_BLKDEV) | |
657 | swap_slot_free_notify = | |
658 | si->bdev->bd_disk->fops->swap_slot_free_notify; | |
659 | else | |
660 | swap_slot_free_notify = NULL; | |
661 | while (offset <= end) { | |
662 | frontswap_invalidate_page(si->type, offset); | |
663 | if (swap_slot_free_notify) | |
664 | swap_slot_free_notify(si->bdev, offset); | |
665 | offset++; | |
666 | } | |
667 | } | |
668 | ||
36005bae TC |
669 | static int scan_swap_map_slots(struct swap_info_struct *si, |
670 | unsigned char usage, int nr, | |
671 | swp_entry_t slots[]) | |
1da177e4 | 672 | { |
235b6217 | 673 | struct swap_cluster_info *ci; |
ebebbbe9 | 674 | unsigned long offset; |
c60aa176 | 675 | unsigned long scan_base; |
7992fde7 | 676 | unsigned long last_in_cluster = 0; |
048c27fd | 677 | int latency_ration = LATENCY_LIMIT; |
36005bae TC |
678 | int n_ret = 0; |
679 | ||
680 | if (nr > SWAP_BATCH) | |
681 | nr = SWAP_BATCH; | |
7dfad418 | 682 | |
886bb7e9 | 683 | /* |
7dfad418 HD |
684 | * We try to cluster swap pages by allocating them sequentially |
685 | * in swap. Once we've allocated SWAPFILE_CLUSTER pages this | |
686 | * way, however, we resort to first-free allocation, starting | |
687 | * a new cluster. This prevents us from scattering swap pages | |
688 | * all over the entire swap partition, so that we reduce | |
689 | * overall disk seek times between swap pages. -- sct | |
690 | * But we do now try to find an empty cluster. -Andrea | |
c60aa176 | 691 | * And we let swap pages go all over an SSD partition. Hugh |
7dfad418 HD |
692 | */ |
693 | ||
52b7efdb | 694 | si->flags += SWP_SCANNING; |
c60aa176 | 695 | scan_base = offset = si->cluster_next; |
ebebbbe9 | 696 | |
ebc2a1a6 SL |
697 | /* SSD algorithm */ |
698 | if (si->cluster_info) { | |
36005bae TC |
699 | if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base)) |
700 | goto checks; | |
701 | else | |
702 | goto scan; | |
ebc2a1a6 SL |
703 | } |
704 | ||
ebebbbe9 HD |
705 | if (unlikely(!si->cluster_nr--)) { |
706 | if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { | |
707 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
708 | goto checks; | |
709 | } | |
2a8f9449 | 710 | |
ec8acf20 | 711 | spin_unlock(&si->lock); |
7dfad418 | 712 | |
c60aa176 HD |
713 | /* |
714 | * If seek is expensive, start searching for new cluster from | |
715 | * start of partition, to minimize the span of allocated swap. | |
50088c44 CY |
716 | * If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info |
717 | * case, just handled by scan_swap_map_try_ssd_cluster() above. | |
c60aa176 | 718 | */ |
50088c44 | 719 | scan_base = offset = si->lowest_bit; |
7dfad418 HD |
720 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
721 | ||
722 | /* Locate the first empty (unaligned) cluster */ | |
723 | for (; last_in_cluster <= si->highest_bit; offset++) { | |
1da177e4 | 724 | if (si->swap_map[offset]) |
7dfad418 HD |
725 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
726 | else if (offset == last_in_cluster) { | |
ec8acf20 | 727 | spin_lock(&si->lock); |
ebebbbe9 HD |
728 | offset -= SWAPFILE_CLUSTER - 1; |
729 | si->cluster_next = offset; | |
730 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
c60aa176 HD |
731 | goto checks; |
732 | } | |
733 | if (unlikely(--latency_ration < 0)) { | |
734 | cond_resched(); | |
735 | latency_ration = LATENCY_LIMIT; | |
736 | } | |
737 | } | |
738 | ||
739 | offset = scan_base; | |
ec8acf20 | 740 | spin_lock(&si->lock); |
ebebbbe9 | 741 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
1da177e4 | 742 | } |
7dfad418 | 743 | |
ebebbbe9 | 744 | checks: |
ebc2a1a6 | 745 | if (si->cluster_info) { |
36005bae TC |
746 | while (scan_swap_map_ssd_cluster_conflict(si, offset)) { |
747 | /* take a break if we already got some slots */ | |
748 | if (n_ret) | |
749 | goto done; | |
750 | if (!scan_swap_map_try_ssd_cluster(si, &offset, | |
751 | &scan_base)) | |
752 | goto scan; | |
753 | } | |
ebc2a1a6 | 754 | } |
ebebbbe9 | 755 | if (!(si->flags & SWP_WRITEOK)) |
52b7efdb | 756 | goto no_page; |
7dfad418 HD |
757 | if (!si->highest_bit) |
758 | goto no_page; | |
ebebbbe9 | 759 | if (offset > si->highest_bit) |
c60aa176 | 760 | scan_base = offset = si->lowest_bit; |
c9e44410 | 761 | |
235b6217 | 762 | ci = lock_cluster(si, offset); |
b73d7fce HD |
763 | /* reuse swap entry of cache-only swap if not busy. */ |
764 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { | |
c9e44410 | 765 | int swap_was_freed; |
235b6217 | 766 | unlock_cluster(ci); |
ec8acf20 | 767 | spin_unlock(&si->lock); |
c9e44410 | 768 | swap_was_freed = __try_to_reclaim_swap(si, offset); |
ec8acf20 | 769 | spin_lock(&si->lock); |
c9e44410 KH |
770 | /* entry was freed successfully, try to use this again */ |
771 | if (swap_was_freed) | |
772 | goto checks; | |
773 | goto scan; /* check next one */ | |
774 | } | |
775 | ||
235b6217 HY |
776 | if (si->swap_map[offset]) { |
777 | unlock_cluster(ci); | |
36005bae TC |
778 | if (!n_ret) |
779 | goto scan; | |
780 | else | |
781 | goto done; | |
235b6217 | 782 | } |
2872bb2d HY |
783 | si->swap_map[offset] = usage; |
784 | inc_cluster_info_page(si, si->cluster_info, offset); | |
785 | unlock_cluster(ci); | |
ebebbbe9 | 786 | |
38d8b4e6 | 787 | swap_range_alloc(si, offset, 1); |
ebebbbe9 | 788 | si->cluster_next = offset + 1; |
36005bae TC |
789 | slots[n_ret++] = swp_entry(si->type, offset); |
790 | ||
791 | /* got enough slots or reach max slots? */ | |
792 | if ((n_ret == nr) || (offset >= si->highest_bit)) | |
793 | goto done; | |
794 | ||
795 | /* search for next available slot */ | |
796 | ||
797 | /* time to take a break? */ | |
798 | if (unlikely(--latency_ration < 0)) { | |
799 | if (n_ret) | |
800 | goto done; | |
801 | spin_unlock(&si->lock); | |
802 | cond_resched(); | |
803 | spin_lock(&si->lock); | |
804 | latency_ration = LATENCY_LIMIT; | |
805 | } | |
806 | ||
807 | /* try to get more slots in cluster */ | |
808 | if (si->cluster_info) { | |
809 | if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base)) | |
810 | goto checks; | |
811 | else | |
812 | goto done; | |
813 | } | |
814 | /* non-ssd case */ | |
815 | ++offset; | |
816 | ||
817 | /* non-ssd case, still more slots in cluster? */ | |
818 | if (si->cluster_nr && !si->swap_map[offset]) { | |
819 | --si->cluster_nr; | |
820 | goto checks; | |
821 | } | |
7992fde7 | 822 | |
36005bae TC |
823 | done: |
824 | si->flags -= SWP_SCANNING; | |
825 | return n_ret; | |
7dfad418 | 826 | |
ebebbbe9 | 827 | scan: |
ec8acf20 | 828 | spin_unlock(&si->lock); |
7dfad418 | 829 | while (++offset <= si->highest_bit) { |
52b7efdb | 830 | if (!si->swap_map[offset]) { |
ec8acf20 | 831 | spin_lock(&si->lock); |
52b7efdb HD |
832 | goto checks; |
833 | } | |
c9e44410 | 834 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
ec8acf20 | 835 | spin_lock(&si->lock); |
c9e44410 KH |
836 | goto checks; |
837 | } | |
048c27fd HD |
838 | if (unlikely(--latency_ration < 0)) { |
839 | cond_resched(); | |
840 | latency_ration = LATENCY_LIMIT; | |
841 | } | |
7dfad418 | 842 | } |
c60aa176 | 843 | offset = si->lowest_bit; |
a5998061 | 844 | while (offset < scan_base) { |
c60aa176 | 845 | if (!si->swap_map[offset]) { |
ec8acf20 | 846 | spin_lock(&si->lock); |
c60aa176 HD |
847 | goto checks; |
848 | } | |
c9e44410 | 849 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
ec8acf20 | 850 | spin_lock(&si->lock); |
c9e44410 KH |
851 | goto checks; |
852 | } | |
c60aa176 HD |
853 | if (unlikely(--latency_ration < 0)) { |
854 | cond_resched(); | |
855 | latency_ration = LATENCY_LIMIT; | |
856 | } | |
a5998061 | 857 | offset++; |
c60aa176 | 858 | } |
ec8acf20 | 859 | spin_lock(&si->lock); |
7dfad418 HD |
860 | |
861 | no_page: | |
52b7efdb | 862 | si->flags -= SWP_SCANNING; |
36005bae | 863 | return n_ret; |
1da177e4 LT |
864 | } |
865 | ||
38d8b4e6 HY |
866 | #ifdef CONFIG_THP_SWAP |
867 | static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) | |
868 | { | |
869 | unsigned long idx; | |
870 | struct swap_cluster_info *ci; | |
871 | unsigned long offset, i; | |
872 | unsigned char *map; | |
873 | ||
874 | if (cluster_list_empty(&si->free_clusters)) | |
875 | return 0; | |
876 | ||
877 | idx = cluster_list_first(&si->free_clusters); | |
878 | offset = idx * SWAPFILE_CLUSTER; | |
879 | ci = lock_cluster(si, offset); | |
880 | alloc_cluster(si, idx); | |
e0709829 | 881 | cluster_set_count_flag(ci, SWAPFILE_CLUSTER, CLUSTER_FLAG_HUGE); |
38d8b4e6 HY |
882 | |
883 | map = si->swap_map + offset; | |
884 | for (i = 0; i < SWAPFILE_CLUSTER; i++) | |
885 | map[i] = SWAP_HAS_CACHE; | |
886 | unlock_cluster(ci); | |
887 | swap_range_alloc(si, offset, SWAPFILE_CLUSTER); | |
888 | *slot = swp_entry(si->type, offset); | |
889 | ||
890 | return 1; | |
891 | } | |
892 | ||
893 | static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) | |
894 | { | |
895 | unsigned long offset = idx * SWAPFILE_CLUSTER; | |
896 | struct swap_cluster_info *ci; | |
897 | ||
898 | ci = lock_cluster(si, offset); | |
899 | cluster_set_count_flag(ci, 0, 0); | |
900 | free_cluster(si, idx); | |
901 | unlock_cluster(ci); | |
902 | swap_range_free(si, offset, SWAPFILE_CLUSTER); | |
903 | } | |
904 | #else | |
905 | static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) | |
906 | { | |
907 | VM_WARN_ON_ONCE(1); | |
908 | return 0; | |
909 | } | |
910 | #endif /* CONFIG_THP_SWAP */ | |
911 | ||
36005bae TC |
912 | static unsigned long scan_swap_map(struct swap_info_struct *si, |
913 | unsigned char usage) | |
914 | { | |
915 | swp_entry_t entry; | |
916 | int n_ret; | |
917 | ||
918 | n_ret = scan_swap_map_slots(si, usage, 1, &entry); | |
919 | ||
920 | if (n_ret) | |
921 | return swp_offset(entry); | |
922 | else | |
923 | return 0; | |
924 | ||
925 | } | |
926 | ||
38d8b4e6 | 927 | int get_swap_pages(int n_goal, bool cluster, swp_entry_t swp_entries[]) |
1da177e4 | 928 | { |
38d8b4e6 | 929 | unsigned long nr_pages = cluster ? SWAPFILE_CLUSTER : 1; |
adfab836 | 930 | struct swap_info_struct *si, *next; |
36005bae TC |
931 | long avail_pgs; |
932 | int n_ret = 0; | |
a2468cc9 | 933 | int node; |
1da177e4 | 934 | |
38d8b4e6 HY |
935 | /* Only single cluster request supported */ |
936 | WARN_ON_ONCE(n_goal > 1 && cluster); | |
937 | ||
938 | avail_pgs = atomic_long_read(&nr_swap_pages) / nr_pages; | |
36005bae | 939 | if (avail_pgs <= 0) |
fb4f88dc | 940 | goto noswap; |
36005bae TC |
941 | |
942 | if (n_goal > SWAP_BATCH) | |
943 | n_goal = SWAP_BATCH; | |
944 | ||
945 | if (n_goal > avail_pgs) | |
946 | n_goal = avail_pgs; | |
947 | ||
38d8b4e6 | 948 | atomic_long_sub(n_goal * nr_pages, &nr_swap_pages); |
fb4f88dc | 949 | |
18ab4d4c DS |
950 | spin_lock(&swap_avail_lock); |
951 | ||
952 | start_over: | |
a2468cc9 AL |
953 | node = numa_node_id(); |
954 | plist_for_each_entry_safe(si, next, &swap_avail_heads[node], avail_lists[node]) { | |
18ab4d4c | 955 | /* requeue si to after same-priority siblings */ |
a2468cc9 | 956 | plist_requeue(&si->avail_lists[node], &swap_avail_heads[node]); |
18ab4d4c | 957 | spin_unlock(&swap_avail_lock); |
ec8acf20 | 958 | spin_lock(&si->lock); |
adfab836 | 959 | if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) { |
18ab4d4c | 960 | spin_lock(&swap_avail_lock); |
a2468cc9 | 961 | if (plist_node_empty(&si->avail_lists[node])) { |
18ab4d4c DS |
962 | spin_unlock(&si->lock); |
963 | goto nextsi; | |
964 | } | |
965 | WARN(!si->highest_bit, | |
966 | "swap_info %d in list but !highest_bit\n", | |
967 | si->type); | |
968 | WARN(!(si->flags & SWP_WRITEOK), | |
969 | "swap_info %d in list but !SWP_WRITEOK\n", | |
970 | si->type); | |
a2468cc9 | 971 | __del_from_avail_list(si); |
ec8acf20 | 972 | spin_unlock(&si->lock); |
18ab4d4c | 973 | goto nextsi; |
ec8acf20 | 974 | } |
f0eea189 HY |
975 | if (cluster) { |
976 | if (!(si->flags & SWP_FILE)) | |
977 | n_ret = swap_alloc_cluster(si, swp_entries); | |
978 | } else | |
38d8b4e6 HY |
979 | n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, |
980 | n_goal, swp_entries); | |
ec8acf20 | 981 | spin_unlock(&si->lock); |
38d8b4e6 | 982 | if (n_ret || cluster) |
36005bae | 983 | goto check_out; |
18ab4d4c | 984 | pr_debug("scan_swap_map of si %d failed to find offset\n", |
36005bae TC |
985 | si->type); |
986 | ||
18ab4d4c DS |
987 | spin_lock(&swap_avail_lock); |
988 | nextsi: | |
adfab836 DS |
989 | /* |
990 | * if we got here, it's likely that si was almost full before, | |
991 | * and since scan_swap_map() can drop the si->lock, multiple | |
992 | * callers probably all tried to get a page from the same si | |
18ab4d4c DS |
993 | * and it filled up before we could get one; or, the si filled |
994 | * up between us dropping swap_avail_lock and taking si->lock. | |
995 | * Since we dropped the swap_avail_lock, the swap_avail_head | |
996 | * list may have been modified; so if next is still in the | |
36005bae TC |
997 | * swap_avail_head list then try it, otherwise start over |
998 | * if we have not gotten any slots. | |
adfab836 | 999 | */ |
a2468cc9 | 1000 | if (plist_node_empty(&next->avail_lists[node])) |
18ab4d4c | 1001 | goto start_over; |
1da177e4 | 1002 | } |
fb4f88dc | 1003 | |
18ab4d4c DS |
1004 | spin_unlock(&swap_avail_lock); |
1005 | ||
36005bae TC |
1006 | check_out: |
1007 | if (n_ret < n_goal) | |
38d8b4e6 HY |
1008 | atomic_long_add((long)(n_goal - n_ret) * nr_pages, |
1009 | &nr_swap_pages); | |
fb4f88dc | 1010 | noswap: |
36005bae TC |
1011 | return n_ret; |
1012 | } | |
1013 | ||
2de1a7e4 | 1014 | /* The only caller of this function is now suspend routine */ |
910321ea HD |
1015 | swp_entry_t get_swap_page_of_type(int type) |
1016 | { | |
1017 | struct swap_info_struct *si; | |
1018 | pgoff_t offset; | |
1019 | ||
910321ea | 1020 | si = swap_info[type]; |
ec8acf20 | 1021 | spin_lock(&si->lock); |
910321ea | 1022 | if (si && (si->flags & SWP_WRITEOK)) { |
ec8acf20 | 1023 | atomic_long_dec(&nr_swap_pages); |
910321ea HD |
1024 | /* This is called for allocating swap entry, not cache */ |
1025 | offset = scan_swap_map(si, 1); | |
1026 | if (offset) { | |
ec8acf20 | 1027 | spin_unlock(&si->lock); |
910321ea HD |
1028 | return swp_entry(type, offset); |
1029 | } | |
ec8acf20 | 1030 | atomic_long_inc(&nr_swap_pages); |
910321ea | 1031 | } |
ec8acf20 | 1032 | spin_unlock(&si->lock); |
910321ea HD |
1033 | return (swp_entry_t) {0}; |
1034 | } | |
1035 | ||
e8c26ab6 | 1036 | static struct swap_info_struct *__swap_info_get(swp_entry_t entry) |
1da177e4 | 1037 | { |
73c34b6a | 1038 | struct swap_info_struct *p; |
1da177e4 LT |
1039 | unsigned long offset, type; |
1040 | ||
1041 | if (!entry.val) | |
1042 | goto out; | |
1043 | type = swp_type(entry); | |
1044 | if (type >= nr_swapfiles) | |
1045 | goto bad_nofile; | |
efa90a98 | 1046 | p = swap_info[type]; |
1da177e4 LT |
1047 | if (!(p->flags & SWP_USED)) |
1048 | goto bad_device; | |
1049 | offset = swp_offset(entry); | |
1050 | if (offset >= p->max) | |
1051 | goto bad_offset; | |
1da177e4 LT |
1052 | return p; |
1053 | ||
1da177e4 | 1054 | bad_offset: |
6a991fc7 | 1055 | pr_err("swap_info_get: %s%08lx\n", Bad_offset, entry.val); |
1da177e4 LT |
1056 | goto out; |
1057 | bad_device: | |
6a991fc7 | 1058 | pr_err("swap_info_get: %s%08lx\n", Unused_file, entry.val); |
1da177e4 LT |
1059 | goto out; |
1060 | bad_nofile: | |
6a991fc7 | 1061 | pr_err("swap_info_get: %s%08lx\n", Bad_file, entry.val); |
1da177e4 LT |
1062 | out: |
1063 | return NULL; | |
886bb7e9 | 1064 | } |
1da177e4 | 1065 | |
e8c26ab6 TC |
1066 | static struct swap_info_struct *_swap_info_get(swp_entry_t entry) |
1067 | { | |
1068 | struct swap_info_struct *p; | |
1069 | ||
1070 | p = __swap_info_get(entry); | |
1071 | if (!p) | |
1072 | goto out; | |
1073 | if (!p->swap_map[swp_offset(entry)]) | |
1074 | goto bad_free; | |
1075 | return p; | |
1076 | ||
1077 | bad_free: | |
1078 | pr_err("swap_info_get: %s%08lx\n", Unused_offset, entry.val); | |
1079 | goto out; | |
1080 | out: | |
1081 | return NULL; | |
1082 | } | |
1083 | ||
235b6217 HY |
1084 | static struct swap_info_struct *swap_info_get(swp_entry_t entry) |
1085 | { | |
1086 | struct swap_info_struct *p; | |
1087 | ||
1088 | p = _swap_info_get(entry); | |
1089 | if (p) | |
1090 | spin_lock(&p->lock); | |
1091 | return p; | |
1092 | } | |
1093 | ||
7c00bafe TC |
1094 | static struct swap_info_struct *swap_info_get_cont(swp_entry_t entry, |
1095 | struct swap_info_struct *q) | |
1096 | { | |
1097 | struct swap_info_struct *p; | |
1098 | ||
1099 | p = _swap_info_get(entry); | |
1100 | ||
1101 | if (p != q) { | |
1102 | if (q != NULL) | |
1103 | spin_unlock(&q->lock); | |
1104 | if (p != NULL) | |
1105 | spin_lock(&p->lock); | |
1106 | } | |
1107 | return p; | |
1108 | } | |
1109 | ||
1110 | static unsigned char __swap_entry_free(struct swap_info_struct *p, | |
1111 | swp_entry_t entry, unsigned char usage) | |
1da177e4 | 1112 | { |
235b6217 | 1113 | struct swap_cluster_info *ci; |
253d553b | 1114 | unsigned long offset = swp_offset(entry); |
8d69aaee HD |
1115 | unsigned char count; |
1116 | unsigned char has_cache; | |
235b6217 | 1117 | |
7c00bafe | 1118 | ci = lock_cluster_or_swap_info(p, offset); |
355cfa73 | 1119 | |
253d553b | 1120 | count = p->swap_map[offset]; |
235b6217 | 1121 | |
253d553b HD |
1122 | has_cache = count & SWAP_HAS_CACHE; |
1123 | count &= ~SWAP_HAS_CACHE; | |
355cfa73 | 1124 | |
253d553b | 1125 | if (usage == SWAP_HAS_CACHE) { |
355cfa73 | 1126 | VM_BUG_ON(!has_cache); |
253d553b | 1127 | has_cache = 0; |
aaa46865 HD |
1128 | } else if (count == SWAP_MAP_SHMEM) { |
1129 | /* | |
1130 | * Or we could insist on shmem.c using a special | |
1131 | * swap_shmem_free() and free_shmem_swap_and_cache()... | |
1132 | */ | |
1133 | count = 0; | |
570a335b HD |
1134 | } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { |
1135 | if (count == COUNT_CONTINUED) { | |
1136 | if (swap_count_continued(p, offset, count)) | |
1137 | count = SWAP_MAP_MAX | COUNT_CONTINUED; | |
1138 | else | |
1139 | count = SWAP_MAP_MAX; | |
1140 | } else | |
1141 | count--; | |
1142 | } | |
253d553b | 1143 | |
253d553b | 1144 | usage = count | has_cache; |
7c00bafe TC |
1145 | p->swap_map[offset] = usage ? : SWAP_HAS_CACHE; |
1146 | ||
1147 | unlock_cluster_or_swap_info(p, ci); | |
1148 | ||
1149 | return usage; | |
1150 | } | |
355cfa73 | 1151 | |
7c00bafe TC |
1152 | static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry) |
1153 | { | |
1154 | struct swap_cluster_info *ci; | |
1155 | unsigned long offset = swp_offset(entry); | |
1156 | unsigned char count; | |
1157 | ||
1158 | ci = lock_cluster(p, offset); | |
1159 | count = p->swap_map[offset]; | |
1160 | VM_BUG_ON(count != SWAP_HAS_CACHE); | |
1161 | p->swap_map[offset] = 0; | |
1162 | dec_cluster_info_page(p, p->cluster_info, offset); | |
235b6217 HY |
1163 | unlock_cluster(ci); |
1164 | ||
38d8b4e6 HY |
1165 | mem_cgroup_uncharge_swap(entry, 1); |
1166 | swap_range_free(p, offset, 1); | |
1da177e4 LT |
1167 | } |
1168 | ||
1169 | /* | |
2de1a7e4 | 1170 | * Caller has made sure that the swap device corresponding to entry |
1da177e4 LT |
1171 | * is still around or has not been recycled. |
1172 | */ | |
1173 | void swap_free(swp_entry_t entry) | |
1174 | { | |
73c34b6a | 1175 | struct swap_info_struct *p; |
1da177e4 | 1176 | |
235b6217 | 1177 | p = _swap_info_get(entry); |
7c00bafe TC |
1178 | if (p) { |
1179 | if (!__swap_entry_free(p, entry, 1)) | |
67afa38e | 1180 | free_swap_slot(entry); |
7c00bafe | 1181 | } |
1da177e4 LT |
1182 | } |
1183 | ||
cb4b86ba KH |
1184 | /* |
1185 | * Called after dropping swapcache to decrease refcnt to swap entries. | |
1186 | */ | |
75f6d6d2 | 1187 | static void swapcache_free(swp_entry_t entry) |
cb4b86ba | 1188 | { |
355cfa73 KH |
1189 | struct swap_info_struct *p; |
1190 | ||
235b6217 | 1191 | p = _swap_info_get(entry); |
7c00bafe TC |
1192 | if (p) { |
1193 | if (!__swap_entry_free(p, entry, SWAP_HAS_CACHE)) | |
67afa38e | 1194 | free_swap_slot(entry); |
7c00bafe TC |
1195 | } |
1196 | } | |
1197 | ||
38d8b4e6 | 1198 | #ifdef CONFIG_THP_SWAP |
75f6d6d2 | 1199 | static void swapcache_free_cluster(swp_entry_t entry) |
38d8b4e6 HY |
1200 | { |
1201 | unsigned long offset = swp_offset(entry); | |
1202 | unsigned long idx = offset / SWAPFILE_CLUSTER; | |
1203 | struct swap_cluster_info *ci; | |
1204 | struct swap_info_struct *si; | |
1205 | unsigned char *map; | |
a3aea839 HY |
1206 | unsigned int i, free_entries = 0; |
1207 | unsigned char val; | |
38d8b4e6 | 1208 | |
a3aea839 | 1209 | si = _swap_info_get(entry); |
38d8b4e6 HY |
1210 | if (!si) |
1211 | return; | |
1212 | ||
1213 | ci = lock_cluster(si, offset); | |
e0709829 | 1214 | VM_BUG_ON(!cluster_is_huge(ci)); |
38d8b4e6 HY |
1215 | map = si->swap_map + offset; |
1216 | for (i = 0; i < SWAPFILE_CLUSTER; i++) { | |
a3aea839 HY |
1217 | val = map[i]; |
1218 | VM_BUG_ON(!(val & SWAP_HAS_CACHE)); | |
1219 | if (val == SWAP_HAS_CACHE) | |
1220 | free_entries++; | |
1221 | } | |
1222 | if (!free_entries) { | |
1223 | for (i = 0; i < SWAPFILE_CLUSTER; i++) | |
1224 | map[i] &= ~SWAP_HAS_CACHE; | |
38d8b4e6 | 1225 | } |
e0709829 | 1226 | cluster_clear_huge(ci); |
38d8b4e6 | 1227 | unlock_cluster(ci); |
a3aea839 HY |
1228 | if (free_entries == SWAPFILE_CLUSTER) { |
1229 | spin_lock(&si->lock); | |
1230 | ci = lock_cluster(si, offset); | |
1231 | memset(map, 0, SWAPFILE_CLUSTER); | |
1232 | unlock_cluster(ci); | |
1233 | mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER); | |
1234 | swap_free_cluster(si, idx); | |
1235 | spin_unlock(&si->lock); | |
1236 | } else if (free_entries) { | |
1237 | for (i = 0; i < SWAPFILE_CLUSTER; i++, entry.val++) { | |
1238 | if (!__swap_entry_free(si, entry, SWAP_HAS_CACHE)) | |
1239 | free_swap_slot(entry); | |
1240 | } | |
1241 | } | |
38d8b4e6 | 1242 | } |
59807685 HY |
1243 | |
1244 | int split_swap_cluster(swp_entry_t entry) | |
1245 | { | |
1246 | struct swap_info_struct *si; | |
1247 | struct swap_cluster_info *ci; | |
1248 | unsigned long offset = swp_offset(entry); | |
1249 | ||
1250 | si = _swap_info_get(entry); | |
1251 | if (!si) | |
1252 | return -EBUSY; | |
1253 | ci = lock_cluster(si, offset); | |
1254 | cluster_clear_huge(ci); | |
1255 | unlock_cluster(ci); | |
1256 | return 0; | |
1257 | } | |
75f6d6d2 MK |
1258 | #else |
1259 | static inline void swapcache_free_cluster(swp_entry_t entry) | |
1260 | { | |
1261 | } | |
38d8b4e6 HY |
1262 | #endif /* CONFIG_THP_SWAP */ |
1263 | ||
75f6d6d2 MK |
1264 | void put_swap_page(struct page *page, swp_entry_t entry) |
1265 | { | |
1266 | if (!PageTransHuge(page)) | |
1267 | swapcache_free(entry); | |
1268 | else | |
1269 | swapcache_free_cluster(entry); | |
1270 | } | |
1271 | ||
155b5f88 HY |
1272 | static int swp_entry_cmp(const void *ent1, const void *ent2) |
1273 | { | |
1274 | const swp_entry_t *e1 = ent1, *e2 = ent2; | |
1275 | ||
1276 | return (int)swp_type(*e1) - (int)swp_type(*e2); | |
1277 | } | |
1278 | ||
7c00bafe TC |
1279 | void swapcache_free_entries(swp_entry_t *entries, int n) |
1280 | { | |
1281 | struct swap_info_struct *p, *prev; | |
1282 | int i; | |
1283 | ||
1284 | if (n <= 0) | |
1285 | return; | |
1286 | ||
1287 | prev = NULL; | |
1288 | p = NULL; | |
155b5f88 HY |
1289 | |
1290 | /* | |
1291 | * Sort swap entries by swap device, so each lock is only taken once. | |
1292 | * nr_swapfiles isn't absolutely correct, but the overhead of sort() is | |
1293 | * so low that it isn't necessary to optimize further. | |
1294 | */ | |
1295 | if (nr_swapfiles > 1) | |
1296 | sort(entries, n, sizeof(entries[0]), swp_entry_cmp, NULL); | |
7c00bafe TC |
1297 | for (i = 0; i < n; ++i) { |
1298 | p = swap_info_get_cont(entries[i], prev); | |
1299 | if (p) | |
1300 | swap_entry_free(p, entries[i]); | |
7c00bafe TC |
1301 | prev = p; |
1302 | } | |
235b6217 | 1303 | if (p) |
7c00bafe | 1304 | spin_unlock(&p->lock); |
cb4b86ba KH |
1305 | } |
1306 | ||
1da177e4 | 1307 | /* |
c475a8ab | 1308 | * How many references to page are currently swapped out? |
570a335b HD |
1309 | * This does not give an exact answer when swap count is continued, |
1310 | * but does include the high COUNT_CONTINUED flag to allow for that. | |
1da177e4 | 1311 | */ |
bde05d1c | 1312 | int page_swapcount(struct page *page) |
1da177e4 | 1313 | { |
c475a8ab HD |
1314 | int count = 0; |
1315 | struct swap_info_struct *p; | |
235b6217 | 1316 | struct swap_cluster_info *ci; |
1da177e4 | 1317 | swp_entry_t entry; |
235b6217 | 1318 | unsigned long offset; |
1da177e4 | 1319 | |
4c21e2f2 | 1320 | entry.val = page_private(page); |
235b6217 | 1321 | p = _swap_info_get(entry); |
1da177e4 | 1322 | if (p) { |
235b6217 HY |
1323 | offset = swp_offset(entry); |
1324 | ci = lock_cluster_or_swap_info(p, offset); | |
1325 | count = swap_count(p->swap_map[offset]); | |
1326 | unlock_cluster_or_swap_info(p, ci); | |
1da177e4 | 1327 | } |
c475a8ab | 1328 | return count; |
1da177e4 LT |
1329 | } |
1330 | ||
322b8afe HY |
1331 | static int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry) |
1332 | { | |
1333 | int count = 0; | |
1334 | pgoff_t offset = swp_offset(entry); | |
1335 | struct swap_cluster_info *ci; | |
1336 | ||
1337 | ci = lock_cluster_or_swap_info(si, offset); | |
1338 | count = swap_count(si->swap_map[offset]); | |
1339 | unlock_cluster_or_swap_info(si, ci); | |
1340 | return count; | |
1341 | } | |
1342 | ||
e8c26ab6 TC |
1343 | /* |
1344 | * How many references to @entry are currently swapped out? | |
1345 | * This does not give an exact answer when swap count is continued, | |
1346 | * but does include the high COUNT_CONTINUED flag to allow for that. | |
1347 | */ | |
1348 | int __swp_swapcount(swp_entry_t entry) | |
1349 | { | |
1350 | int count = 0; | |
e8c26ab6 | 1351 | struct swap_info_struct *si; |
e8c26ab6 TC |
1352 | |
1353 | si = __swap_info_get(entry); | |
322b8afe HY |
1354 | if (si) |
1355 | count = swap_swapcount(si, entry); | |
e8c26ab6 TC |
1356 | return count; |
1357 | } | |
1358 | ||
8334b962 MK |
1359 | /* |
1360 | * How many references to @entry are currently swapped out? | |
1361 | * This considers COUNT_CONTINUED so it returns exact answer. | |
1362 | */ | |
1363 | int swp_swapcount(swp_entry_t entry) | |
1364 | { | |
1365 | int count, tmp_count, n; | |
1366 | struct swap_info_struct *p; | |
235b6217 | 1367 | struct swap_cluster_info *ci; |
8334b962 MK |
1368 | struct page *page; |
1369 | pgoff_t offset; | |
1370 | unsigned char *map; | |
1371 | ||
235b6217 | 1372 | p = _swap_info_get(entry); |
8334b962 MK |
1373 | if (!p) |
1374 | return 0; | |
1375 | ||
235b6217 HY |
1376 | offset = swp_offset(entry); |
1377 | ||
1378 | ci = lock_cluster_or_swap_info(p, offset); | |
1379 | ||
1380 | count = swap_count(p->swap_map[offset]); | |
8334b962 MK |
1381 | if (!(count & COUNT_CONTINUED)) |
1382 | goto out; | |
1383 | ||
1384 | count &= ~COUNT_CONTINUED; | |
1385 | n = SWAP_MAP_MAX + 1; | |
1386 | ||
8334b962 MK |
1387 | page = vmalloc_to_page(p->swap_map + offset); |
1388 | offset &= ~PAGE_MASK; | |
1389 | VM_BUG_ON(page_private(page) != SWP_CONTINUED); | |
1390 | ||
1391 | do { | |
a8ae4991 | 1392 | page = list_next_entry(page, lru); |
8334b962 MK |
1393 | map = kmap_atomic(page); |
1394 | tmp_count = map[offset]; | |
1395 | kunmap_atomic(map); | |
1396 | ||
1397 | count += (tmp_count & ~COUNT_CONTINUED) * n; | |
1398 | n *= (SWAP_CONT_MAX + 1); | |
1399 | } while (tmp_count & COUNT_CONTINUED); | |
1400 | out: | |
235b6217 | 1401 | unlock_cluster_or_swap_info(p, ci); |
8334b962 MK |
1402 | return count; |
1403 | } | |
1404 | ||
e0709829 HY |
1405 | #ifdef CONFIG_THP_SWAP |
1406 | static bool swap_page_trans_huge_swapped(struct swap_info_struct *si, | |
1407 | swp_entry_t entry) | |
1408 | { | |
1409 | struct swap_cluster_info *ci; | |
1410 | unsigned char *map = si->swap_map; | |
1411 | unsigned long roffset = swp_offset(entry); | |
1412 | unsigned long offset = round_down(roffset, SWAPFILE_CLUSTER); | |
1413 | int i; | |
1414 | bool ret = false; | |
1415 | ||
1416 | ci = lock_cluster_or_swap_info(si, offset); | |
1417 | if (!ci || !cluster_is_huge(ci)) { | |
1418 | if (map[roffset] != SWAP_HAS_CACHE) | |
1419 | ret = true; | |
1420 | goto unlock_out; | |
1421 | } | |
1422 | for (i = 0; i < SWAPFILE_CLUSTER; i++) { | |
1423 | if (map[offset + i] != SWAP_HAS_CACHE) { | |
1424 | ret = true; | |
1425 | break; | |
1426 | } | |
1427 | } | |
1428 | unlock_out: | |
1429 | unlock_cluster_or_swap_info(si, ci); | |
1430 | return ret; | |
1431 | } | |
1432 | ||
1433 | static bool page_swapped(struct page *page) | |
1434 | { | |
1435 | swp_entry_t entry; | |
1436 | struct swap_info_struct *si; | |
1437 | ||
1438 | if (likely(!PageTransCompound(page))) | |
1439 | return page_swapcount(page) != 0; | |
1440 | ||
1441 | page = compound_head(page); | |
1442 | entry.val = page_private(page); | |
1443 | si = _swap_info_get(entry); | |
1444 | if (si) | |
1445 | return swap_page_trans_huge_swapped(si, entry); | |
1446 | return false; | |
1447 | } | |
ba3c4ce6 HY |
1448 | |
1449 | static int page_trans_huge_map_swapcount(struct page *page, int *total_mapcount, | |
1450 | int *total_swapcount) | |
1451 | { | |
1452 | int i, map_swapcount, _total_mapcount, _total_swapcount; | |
1453 | unsigned long offset = 0; | |
1454 | struct swap_info_struct *si; | |
1455 | struct swap_cluster_info *ci = NULL; | |
1456 | unsigned char *map = NULL; | |
1457 | int mapcount, swapcount = 0; | |
1458 | ||
1459 | /* hugetlbfs shouldn't call it */ | |
1460 | VM_BUG_ON_PAGE(PageHuge(page), page); | |
1461 | ||
1462 | if (likely(!PageTransCompound(page))) { | |
1463 | mapcount = atomic_read(&page->_mapcount) + 1; | |
1464 | if (total_mapcount) | |
1465 | *total_mapcount = mapcount; | |
1466 | if (PageSwapCache(page)) | |
1467 | swapcount = page_swapcount(page); | |
1468 | if (total_swapcount) | |
1469 | *total_swapcount = swapcount; | |
1470 | return mapcount + swapcount; | |
1471 | } | |
1472 | ||
1473 | page = compound_head(page); | |
1474 | ||
1475 | _total_mapcount = _total_swapcount = map_swapcount = 0; | |
1476 | if (PageSwapCache(page)) { | |
1477 | swp_entry_t entry; | |
1478 | ||
1479 | entry.val = page_private(page); | |
1480 | si = _swap_info_get(entry); | |
1481 | if (si) { | |
1482 | map = si->swap_map; | |
1483 | offset = swp_offset(entry); | |
1484 | } | |
1485 | } | |
1486 | if (map) | |
1487 | ci = lock_cluster(si, offset); | |
1488 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1489 | mapcount = atomic_read(&page[i]._mapcount) + 1; | |
1490 | _total_mapcount += mapcount; | |
1491 | if (map) { | |
1492 | swapcount = swap_count(map[offset + i]); | |
1493 | _total_swapcount += swapcount; | |
1494 | } | |
1495 | map_swapcount = max(map_swapcount, mapcount + swapcount); | |
1496 | } | |
1497 | unlock_cluster(ci); | |
1498 | if (PageDoubleMap(page)) { | |
1499 | map_swapcount -= 1; | |
1500 | _total_mapcount -= HPAGE_PMD_NR; | |
1501 | } | |
1502 | mapcount = compound_mapcount(page); | |
1503 | map_swapcount += mapcount; | |
1504 | _total_mapcount += mapcount; | |
1505 | if (total_mapcount) | |
1506 | *total_mapcount = _total_mapcount; | |
1507 | if (total_swapcount) | |
1508 | *total_swapcount = _total_swapcount; | |
1509 | ||
1510 | return map_swapcount; | |
1511 | } | |
e0709829 HY |
1512 | #else |
1513 | #define swap_page_trans_huge_swapped(si, entry) swap_swapcount(si, entry) | |
1514 | #define page_swapped(page) (page_swapcount(page) != 0) | |
ba3c4ce6 HY |
1515 | |
1516 | static int page_trans_huge_map_swapcount(struct page *page, int *total_mapcount, | |
1517 | int *total_swapcount) | |
1518 | { | |
1519 | int mapcount, swapcount = 0; | |
1520 | ||
1521 | /* hugetlbfs shouldn't call it */ | |
1522 | VM_BUG_ON_PAGE(PageHuge(page), page); | |
1523 | ||
1524 | mapcount = page_trans_huge_mapcount(page, total_mapcount); | |
1525 | if (PageSwapCache(page)) | |
1526 | swapcount = page_swapcount(page); | |
1527 | if (total_swapcount) | |
1528 | *total_swapcount = swapcount; | |
1529 | return mapcount + swapcount; | |
1530 | } | |
e0709829 HY |
1531 | #endif |
1532 | ||
1da177e4 | 1533 | /* |
7b1fe597 HD |
1534 | * We can write to an anon page without COW if there are no other references |
1535 | * to it. And as a side-effect, free up its swap: because the old content | |
1536 | * on disk will never be read, and seeking back there to write new content | |
1537 | * later would only waste time away from clustering. | |
6d0a07ed | 1538 | * |
ba3c4ce6 | 1539 | * NOTE: total_map_swapcount should not be relied upon by the caller if |
6d0a07ed AA |
1540 | * reuse_swap_page() returns false, but it may be always overwritten |
1541 | * (see the other implementation for CONFIG_SWAP=n). | |
1da177e4 | 1542 | */ |
ba3c4ce6 | 1543 | bool reuse_swap_page(struct page *page, int *total_map_swapcount) |
1da177e4 | 1544 | { |
ba3c4ce6 | 1545 | int count, total_mapcount, total_swapcount; |
c475a8ab | 1546 | |
309381fe | 1547 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
5ad64688 | 1548 | if (unlikely(PageKsm(page))) |
6d0a07ed | 1549 | return false; |
ba3c4ce6 HY |
1550 | count = page_trans_huge_map_swapcount(page, &total_mapcount, |
1551 | &total_swapcount); | |
1552 | if (total_map_swapcount) | |
1553 | *total_map_swapcount = total_mapcount + total_swapcount; | |
1554 | if (count == 1 && PageSwapCache(page) && | |
1555 | (likely(!PageTransCompound(page)) || | |
1556 | /* The remaining swap count will be freed soon */ | |
1557 | total_swapcount == page_swapcount(page))) { | |
f0571429 | 1558 | if (!PageWriteback(page)) { |
ba3c4ce6 | 1559 | page = compound_head(page); |
7b1fe597 HD |
1560 | delete_from_swap_cache(page); |
1561 | SetPageDirty(page); | |
f0571429 MK |
1562 | } else { |
1563 | swp_entry_t entry; | |
1564 | struct swap_info_struct *p; | |
1565 | ||
1566 | entry.val = page_private(page); | |
1567 | p = swap_info_get(entry); | |
1568 | if (p->flags & SWP_STABLE_WRITES) { | |
1569 | spin_unlock(&p->lock); | |
1570 | return false; | |
1571 | } | |
1572 | spin_unlock(&p->lock); | |
7b1fe597 HD |
1573 | } |
1574 | } | |
ba3c4ce6 | 1575 | |
5ad64688 | 1576 | return count <= 1; |
1da177e4 LT |
1577 | } |
1578 | ||
1579 | /* | |
a2c43eed HD |
1580 | * If swap is getting full, or if there are no more mappings of this page, |
1581 | * then try_to_free_swap is called to free its swap space. | |
1da177e4 | 1582 | */ |
a2c43eed | 1583 | int try_to_free_swap(struct page *page) |
1da177e4 | 1584 | { |
309381fe | 1585 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
1da177e4 LT |
1586 | |
1587 | if (!PageSwapCache(page)) | |
1588 | return 0; | |
1589 | if (PageWriteback(page)) | |
1590 | return 0; | |
e0709829 | 1591 | if (page_swapped(page)) |
1da177e4 LT |
1592 | return 0; |
1593 | ||
b73d7fce HD |
1594 | /* |
1595 | * Once hibernation has begun to create its image of memory, | |
1596 | * there's a danger that one of the calls to try_to_free_swap() | |
1597 | * - most probably a call from __try_to_reclaim_swap() while | |
1598 | * hibernation is allocating its own swap pages for the image, | |
1599 | * but conceivably even a call from memory reclaim - will free | |
1600 | * the swap from a page which has already been recorded in the | |
1601 | * image as a clean swapcache page, and then reuse its swap for | |
1602 | * another page of the image. On waking from hibernation, the | |
1603 | * original page might be freed under memory pressure, then | |
1604 | * later read back in from swap, now with the wrong data. | |
1605 | * | |
2de1a7e4 | 1606 | * Hibernation suspends storage while it is writing the image |
f90ac398 | 1607 | * to disk so check that here. |
b73d7fce | 1608 | */ |
f90ac398 | 1609 | if (pm_suspended_storage()) |
b73d7fce HD |
1610 | return 0; |
1611 | ||
e0709829 | 1612 | page = compound_head(page); |
a2c43eed HD |
1613 | delete_from_swap_cache(page); |
1614 | SetPageDirty(page); | |
1615 | return 1; | |
68a22394 RR |
1616 | } |
1617 | ||
1da177e4 LT |
1618 | /* |
1619 | * Free the swap entry like above, but also try to | |
1620 | * free the page cache entry if it is the last user. | |
1621 | */ | |
2509ef26 | 1622 | int free_swap_and_cache(swp_entry_t entry) |
1da177e4 | 1623 | { |
2509ef26 | 1624 | struct swap_info_struct *p; |
1da177e4 | 1625 | struct page *page = NULL; |
7c00bafe | 1626 | unsigned char count; |
1da177e4 | 1627 | |
a7420aa5 | 1628 | if (non_swap_entry(entry)) |
2509ef26 | 1629 | return 1; |
0697212a | 1630 | |
7c00bafe | 1631 | p = _swap_info_get(entry); |
1da177e4 | 1632 | if (p) { |
7c00bafe | 1633 | count = __swap_entry_free(p, entry, 1); |
e0709829 HY |
1634 | if (count == SWAP_HAS_CACHE && |
1635 | !swap_page_trans_huge_swapped(p, entry)) { | |
33806f06 | 1636 | page = find_get_page(swap_address_space(entry), |
f6ab1f7f | 1637 | swp_offset(entry)); |
8413ac9d | 1638 | if (page && !trylock_page(page)) { |
09cbfeaf | 1639 | put_page(page); |
93fac704 NP |
1640 | page = NULL; |
1641 | } | |
7c00bafe | 1642 | } else if (!count) |
67afa38e | 1643 | free_swap_slot(entry); |
1da177e4 LT |
1644 | } |
1645 | if (page) { | |
a2c43eed HD |
1646 | /* |
1647 | * Not mapped elsewhere, or swap space full? Free it! | |
1648 | * Also recheck PageSwapCache now page is locked (above). | |
1649 | */ | |
93fac704 | 1650 | if (PageSwapCache(page) && !PageWriteback(page) && |
322b8afe | 1651 | (!page_mapped(page) || mem_cgroup_swap_full(page)) && |
e0709829 HY |
1652 | !swap_page_trans_huge_swapped(p, entry)) { |
1653 | page = compound_head(page); | |
1da177e4 LT |
1654 | delete_from_swap_cache(page); |
1655 | SetPageDirty(page); | |
1656 | } | |
1657 | unlock_page(page); | |
09cbfeaf | 1658 | put_page(page); |
1da177e4 | 1659 | } |
2509ef26 | 1660 | return p != NULL; |
1da177e4 LT |
1661 | } |
1662 | ||
b0cb1a19 | 1663 | #ifdef CONFIG_HIBERNATION |
f577eb30 | 1664 | /* |
915bae9e | 1665 | * Find the swap type that corresponds to given device (if any). |
f577eb30 | 1666 | * |
915bae9e RW |
1667 | * @offset - number of the PAGE_SIZE-sized block of the device, starting |
1668 | * from 0, in which the swap header is expected to be located. | |
1669 | * | |
1670 | * This is needed for the suspend to disk (aka swsusp). | |
f577eb30 | 1671 | */ |
7bf23687 | 1672 | int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) |
f577eb30 | 1673 | { |
915bae9e | 1674 | struct block_device *bdev = NULL; |
efa90a98 | 1675 | int type; |
f577eb30 | 1676 | |
915bae9e RW |
1677 | if (device) |
1678 | bdev = bdget(device); | |
1679 | ||
f577eb30 | 1680 | spin_lock(&swap_lock); |
efa90a98 HD |
1681 | for (type = 0; type < nr_swapfiles; type++) { |
1682 | struct swap_info_struct *sis = swap_info[type]; | |
f577eb30 | 1683 | |
915bae9e | 1684 | if (!(sis->flags & SWP_WRITEOK)) |
f577eb30 | 1685 | continue; |
b6b5bce3 | 1686 | |
915bae9e | 1687 | if (!bdev) { |
7bf23687 | 1688 | if (bdev_p) |
dddac6a7 | 1689 | *bdev_p = bdgrab(sis->bdev); |
7bf23687 | 1690 | |
6e1819d6 | 1691 | spin_unlock(&swap_lock); |
efa90a98 | 1692 | return type; |
6e1819d6 | 1693 | } |
915bae9e | 1694 | if (bdev == sis->bdev) { |
9625a5f2 | 1695 | struct swap_extent *se = &sis->first_swap_extent; |
915bae9e | 1696 | |
915bae9e | 1697 | if (se->start_block == offset) { |
7bf23687 | 1698 | if (bdev_p) |
dddac6a7 | 1699 | *bdev_p = bdgrab(sis->bdev); |
7bf23687 | 1700 | |
915bae9e RW |
1701 | spin_unlock(&swap_lock); |
1702 | bdput(bdev); | |
efa90a98 | 1703 | return type; |
915bae9e | 1704 | } |
f577eb30 RW |
1705 | } |
1706 | } | |
1707 | spin_unlock(&swap_lock); | |
915bae9e RW |
1708 | if (bdev) |
1709 | bdput(bdev); | |
1710 | ||
f577eb30 RW |
1711 | return -ENODEV; |
1712 | } | |
1713 | ||
73c34b6a HD |
1714 | /* |
1715 | * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev | |
1716 | * corresponding to given index in swap_info (swap type). | |
1717 | */ | |
1718 | sector_t swapdev_block(int type, pgoff_t offset) | |
1719 | { | |
1720 | struct block_device *bdev; | |
1721 | ||
1722 | if ((unsigned int)type >= nr_swapfiles) | |
1723 | return 0; | |
1724 | if (!(swap_info[type]->flags & SWP_WRITEOK)) | |
1725 | return 0; | |
d4906e1a | 1726 | return map_swap_entry(swp_entry(type, offset), &bdev); |
73c34b6a HD |
1727 | } |
1728 | ||
f577eb30 RW |
1729 | /* |
1730 | * Return either the total number of swap pages of given type, or the number | |
1731 | * of free pages of that type (depending on @free) | |
1732 | * | |
1733 | * This is needed for software suspend | |
1734 | */ | |
1735 | unsigned int count_swap_pages(int type, int free) | |
1736 | { | |
1737 | unsigned int n = 0; | |
1738 | ||
efa90a98 HD |
1739 | spin_lock(&swap_lock); |
1740 | if ((unsigned int)type < nr_swapfiles) { | |
1741 | struct swap_info_struct *sis = swap_info[type]; | |
1742 | ||
ec8acf20 | 1743 | spin_lock(&sis->lock); |
efa90a98 HD |
1744 | if (sis->flags & SWP_WRITEOK) { |
1745 | n = sis->pages; | |
f577eb30 | 1746 | if (free) |
efa90a98 | 1747 | n -= sis->inuse_pages; |
f577eb30 | 1748 | } |
ec8acf20 | 1749 | spin_unlock(&sis->lock); |
f577eb30 | 1750 | } |
efa90a98 | 1751 | spin_unlock(&swap_lock); |
f577eb30 RW |
1752 | return n; |
1753 | } | |
73c34b6a | 1754 | #endif /* CONFIG_HIBERNATION */ |
f577eb30 | 1755 | |
9f8bdb3f | 1756 | static inline int pte_same_as_swp(pte_t pte, pte_t swp_pte) |
179ef71c | 1757 | { |
9f8bdb3f | 1758 | return pte_same(pte_swp_clear_soft_dirty(pte), swp_pte); |
179ef71c CG |
1759 | } |
1760 | ||
1da177e4 | 1761 | /* |
72866f6f HD |
1762 | * No need to decide whether this PTE shares the swap entry with others, |
1763 | * just let do_wp_page work it out if a write is requested later - to | |
1764 | * force COW, vm_page_prot omits write permission from any private vma. | |
1da177e4 | 1765 | */ |
044d66c1 | 1766 | static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
1da177e4 LT |
1767 | unsigned long addr, swp_entry_t entry, struct page *page) |
1768 | { | |
9e16b7fb | 1769 | struct page *swapcache; |
72835c86 | 1770 | struct mem_cgroup *memcg; |
044d66c1 HD |
1771 | spinlock_t *ptl; |
1772 | pte_t *pte; | |
1773 | int ret = 1; | |
1774 | ||
9e16b7fb HD |
1775 | swapcache = page; |
1776 | page = ksm_might_need_to_copy(page, vma, addr); | |
1777 | if (unlikely(!page)) | |
1778 | return -ENOMEM; | |
1779 | ||
f627c2f5 KS |
1780 | if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, |
1781 | &memcg, false)) { | |
044d66c1 | 1782 | ret = -ENOMEM; |
85d9fc89 KH |
1783 | goto out_nolock; |
1784 | } | |
044d66c1 HD |
1785 | |
1786 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); | |
9f8bdb3f | 1787 | if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) { |
f627c2f5 | 1788 | mem_cgroup_cancel_charge(page, memcg, false); |
044d66c1 HD |
1789 | ret = 0; |
1790 | goto out; | |
1791 | } | |
8a9f3ccd | 1792 | |
b084d435 | 1793 | dec_mm_counter(vma->vm_mm, MM_SWAPENTS); |
d559db08 | 1794 | inc_mm_counter(vma->vm_mm, MM_ANONPAGES); |
1da177e4 LT |
1795 | get_page(page); |
1796 | set_pte_at(vma->vm_mm, addr, pte, | |
1797 | pte_mkold(mk_pte(page, vma->vm_page_prot))); | |
00501b53 | 1798 | if (page == swapcache) { |
d281ee61 | 1799 | page_add_anon_rmap(page, vma, addr, false); |
f627c2f5 | 1800 | mem_cgroup_commit_charge(page, memcg, true, false); |
00501b53 | 1801 | } else { /* ksm created a completely new copy */ |
d281ee61 | 1802 | page_add_new_anon_rmap(page, vma, addr, false); |
f627c2f5 | 1803 | mem_cgroup_commit_charge(page, memcg, false, false); |
00501b53 JW |
1804 | lru_cache_add_active_or_unevictable(page, vma); |
1805 | } | |
1da177e4 LT |
1806 | swap_free(entry); |
1807 | /* | |
1808 | * Move the page to the active list so it is not | |
1809 | * immediately swapped out again after swapon. | |
1810 | */ | |
1811 | activate_page(page); | |
044d66c1 HD |
1812 | out: |
1813 | pte_unmap_unlock(pte, ptl); | |
85d9fc89 | 1814 | out_nolock: |
9e16b7fb HD |
1815 | if (page != swapcache) { |
1816 | unlock_page(page); | |
1817 | put_page(page); | |
1818 | } | |
044d66c1 | 1819 | return ret; |
1da177e4 LT |
1820 | } |
1821 | ||
1822 | static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, | |
1823 | unsigned long addr, unsigned long end, | |
1824 | swp_entry_t entry, struct page *page) | |
1825 | { | |
1da177e4 | 1826 | pte_t swp_pte = swp_entry_to_pte(entry); |
705e87c0 | 1827 | pte_t *pte; |
8a9f3ccd | 1828 | int ret = 0; |
1da177e4 | 1829 | |
044d66c1 HD |
1830 | /* |
1831 | * We don't actually need pte lock while scanning for swp_pte: since | |
1832 | * we hold page lock and mmap_sem, swp_pte cannot be inserted into the | |
1833 | * page table while we're scanning; though it could get zapped, and on | |
1834 | * some architectures (e.g. x86_32 with PAE) we might catch a glimpse | |
1835 | * of unmatched parts which look like swp_pte, so unuse_pte must | |
1836 | * recheck under pte lock. Scanning without pte lock lets it be | |
2de1a7e4 | 1837 | * preemptable whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE. |
044d66c1 HD |
1838 | */ |
1839 | pte = pte_offset_map(pmd, addr); | |
1da177e4 LT |
1840 | do { |
1841 | /* | |
1842 | * swapoff spends a _lot_ of time in this loop! | |
1843 | * Test inline before going to call unuse_pte. | |
1844 | */ | |
9f8bdb3f | 1845 | if (unlikely(pte_same_as_swp(*pte, swp_pte))) { |
044d66c1 HD |
1846 | pte_unmap(pte); |
1847 | ret = unuse_pte(vma, pmd, addr, entry, page); | |
1848 | if (ret) | |
1849 | goto out; | |
1850 | pte = pte_offset_map(pmd, addr); | |
1da177e4 LT |
1851 | } |
1852 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
044d66c1 HD |
1853 | pte_unmap(pte - 1); |
1854 | out: | |
8a9f3ccd | 1855 | return ret; |
1da177e4 LT |
1856 | } |
1857 | ||
1858 | static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, | |
1859 | unsigned long addr, unsigned long end, | |
1860 | swp_entry_t entry, struct page *page) | |
1861 | { | |
1862 | pmd_t *pmd; | |
1863 | unsigned long next; | |
8a9f3ccd | 1864 | int ret; |
1da177e4 LT |
1865 | |
1866 | pmd = pmd_offset(pud, addr); | |
1867 | do { | |
dc644a07 | 1868 | cond_resched(); |
1da177e4 | 1869 | next = pmd_addr_end(addr, end); |
1a5a9906 | 1870 | if (pmd_none_or_trans_huge_or_clear_bad(pmd)) |
1da177e4 | 1871 | continue; |
8a9f3ccd BS |
1872 | ret = unuse_pte_range(vma, pmd, addr, next, entry, page); |
1873 | if (ret) | |
1874 | return ret; | |
1da177e4 LT |
1875 | } while (pmd++, addr = next, addr != end); |
1876 | return 0; | |
1877 | } | |
1878 | ||
c2febafc | 1879 | static inline int unuse_pud_range(struct vm_area_struct *vma, p4d_t *p4d, |
1da177e4 LT |
1880 | unsigned long addr, unsigned long end, |
1881 | swp_entry_t entry, struct page *page) | |
1882 | { | |
1883 | pud_t *pud; | |
1884 | unsigned long next; | |
8a9f3ccd | 1885 | int ret; |
1da177e4 | 1886 | |
c2febafc | 1887 | pud = pud_offset(p4d, addr); |
1da177e4 LT |
1888 | do { |
1889 | next = pud_addr_end(addr, end); | |
1890 | if (pud_none_or_clear_bad(pud)) | |
1891 | continue; | |
8a9f3ccd BS |
1892 | ret = unuse_pmd_range(vma, pud, addr, next, entry, page); |
1893 | if (ret) | |
1894 | return ret; | |
1da177e4 LT |
1895 | } while (pud++, addr = next, addr != end); |
1896 | return 0; | |
1897 | } | |
1898 | ||
c2febafc KS |
1899 | static inline int unuse_p4d_range(struct vm_area_struct *vma, pgd_t *pgd, |
1900 | unsigned long addr, unsigned long end, | |
1901 | swp_entry_t entry, struct page *page) | |
1902 | { | |
1903 | p4d_t *p4d; | |
1904 | unsigned long next; | |
1905 | int ret; | |
1906 | ||
1907 | p4d = p4d_offset(pgd, addr); | |
1908 | do { | |
1909 | next = p4d_addr_end(addr, end); | |
1910 | if (p4d_none_or_clear_bad(p4d)) | |
1911 | continue; | |
1912 | ret = unuse_pud_range(vma, p4d, addr, next, entry, page); | |
1913 | if (ret) | |
1914 | return ret; | |
1915 | } while (p4d++, addr = next, addr != end); | |
1916 | return 0; | |
1917 | } | |
1918 | ||
1da177e4 LT |
1919 | static int unuse_vma(struct vm_area_struct *vma, |
1920 | swp_entry_t entry, struct page *page) | |
1921 | { | |
1922 | pgd_t *pgd; | |
1923 | unsigned long addr, end, next; | |
8a9f3ccd | 1924 | int ret; |
1da177e4 | 1925 | |
3ca7b3c5 | 1926 | if (page_anon_vma(page)) { |
1da177e4 LT |
1927 | addr = page_address_in_vma(page, vma); |
1928 | if (addr == -EFAULT) | |
1929 | return 0; | |
1930 | else | |
1931 | end = addr + PAGE_SIZE; | |
1932 | } else { | |
1933 | addr = vma->vm_start; | |
1934 | end = vma->vm_end; | |
1935 | } | |
1936 | ||
1937 | pgd = pgd_offset(vma->vm_mm, addr); | |
1938 | do { | |
1939 | next = pgd_addr_end(addr, end); | |
1940 | if (pgd_none_or_clear_bad(pgd)) | |
1941 | continue; | |
c2febafc | 1942 | ret = unuse_p4d_range(vma, pgd, addr, next, entry, page); |
8a9f3ccd BS |
1943 | if (ret) |
1944 | return ret; | |
1da177e4 LT |
1945 | } while (pgd++, addr = next, addr != end); |
1946 | return 0; | |
1947 | } | |
1948 | ||
1949 | static int unuse_mm(struct mm_struct *mm, | |
1950 | swp_entry_t entry, struct page *page) | |
1951 | { | |
1952 | struct vm_area_struct *vma; | |
8a9f3ccd | 1953 | int ret = 0; |
1da177e4 LT |
1954 | |
1955 | if (!down_read_trylock(&mm->mmap_sem)) { | |
1956 | /* | |
7d03431c FLVC |
1957 | * Activate page so shrink_inactive_list is unlikely to unmap |
1958 | * its ptes while lock is dropped, so swapoff can make progress. | |
1da177e4 | 1959 | */ |
c475a8ab | 1960 | activate_page(page); |
1da177e4 LT |
1961 | unlock_page(page); |
1962 | down_read(&mm->mmap_sem); | |
1963 | lock_page(page); | |
1964 | } | |
1da177e4 | 1965 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
8a9f3ccd | 1966 | if (vma->anon_vma && (ret = unuse_vma(vma, entry, page))) |
1da177e4 | 1967 | break; |
dc644a07 | 1968 | cond_resched(); |
1da177e4 | 1969 | } |
1da177e4 | 1970 | up_read(&mm->mmap_sem); |
8a9f3ccd | 1971 | return (ret < 0)? ret: 0; |
1da177e4 LT |
1972 | } |
1973 | ||
1974 | /* | |
38b5faf4 DM |
1975 | * Scan swap_map (or frontswap_map if frontswap parameter is true) |
1976 | * from current position to next entry still in use. | |
1da177e4 LT |
1977 | * Recycle to start on reaching the end, returning 0 when empty. |
1978 | */ | |
6eb396dc | 1979 | static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
38b5faf4 | 1980 | unsigned int prev, bool frontswap) |
1da177e4 | 1981 | { |
6eb396dc HD |
1982 | unsigned int max = si->max; |
1983 | unsigned int i = prev; | |
8d69aaee | 1984 | unsigned char count; |
1da177e4 LT |
1985 | |
1986 | /* | |
5d337b91 | 1987 | * No need for swap_lock here: we're just looking |
1da177e4 LT |
1988 | * for whether an entry is in use, not modifying it; false |
1989 | * hits are okay, and sys_swapoff() has already prevented new | |
5d337b91 | 1990 | * allocations from this area (while holding swap_lock). |
1da177e4 LT |
1991 | */ |
1992 | for (;;) { | |
1993 | if (++i >= max) { | |
1994 | if (!prev) { | |
1995 | i = 0; | |
1996 | break; | |
1997 | } | |
1998 | /* | |
1999 | * No entries in use at top of swap_map, | |
2000 | * loop back to start and recheck there. | |
2001 | */ | |
2002 | max = prev + 1; | |
2003 | prev = 0; | |
2004 | i = 1; | |
2005 | } | |
4db0c3c2 | 2006 | count = READ_ONCE(si->swap_map[i]); |
355cfa73 | 2007 | if (count && swap_count(count) != SWAP_MAP_BAD) |
dc644a07 HD |
2008 | if (!frontswap || frontswap_test(si, i)) |
2009 | break; | |
2010 | if ((i % LATENCY_LIMIT) == 0) | |
2011 | cond_resched(); | |
1da177e4 LT |
2012 | } |
2013 | return i; | |
2014 | } | |
2015 | ||
2016 | /* | |
2017 | * We completely avoid races by reading each swap page in advance, | |
2018 | * and then search for the process using it. All the necessary | |
2019 | * page table adjustments can then be made atomically. | |
38b5faf4 DM |
2020 | * |
2021 | * if the boolean frontswap is true, only unuse pages_to_unuse pages; | |
2022 | * pages_to_unuse==0 means all pages; ignored if frontswap is false | |
1da177e4 | 2023 | */ |
38b5faf4 DM |
2024 | int try_to_unuse(unsigned int type, bool frontswap, |
2025 | unsigned long pages_to_unuse) | |
1da177e4 | 2026 | { |
efa90a98 | 2027 | struct swap_info_struct *si = swap_info[type]; |
1da177e4 | 2028 | struct mm_struct *start_mm; |
edfe23da SL |
2029 | volatile unsigned char *swap_map; /* swap_map is accessed without |
2030 | * locking. Mark it as volatile | |
2031 | * to prevent compiler doing | |
2032 | * something odd. | |
2033 | */ | |
8d69aaee | 2034 | unsigned char swcount; |
1da177e4 LT |
2035 | struct page *page; |
2036 | swp_entry_t entry; | |
6eb396dc | 2037 | unsigned int i = 0; |
1da177e4 | 2038 | int retval = 0; |
1da177e4 LT |
2039 | |
2040 | /* | |
2041 | * When searching mms for an entry, a good strategy is to | |
2042 | * start at the first mm we freed the previous entry from | |
2043 | * (though actually we don't notice whether we or coincidence | |
2044 | * freed the entry). Initialize this start_mm with a hold. | |
2045 | * | |
2046 | * A simpler strategy would be to start at the last mm we | |
2047 | * freed the previous entry from; but that would take less | |
2048 | * advantage of mmlist ordering, which clusters forked mms | |
2049 | * together, child after parent. If we race with dup_mmap(), we | |
2050 | * prefer to resolve parent before child, lest we miss entries | |
2051 | * duplicated after we scanned child: using last mm would invert | |
570a335b | 2052 | * that. |
1da177e4 LT |
2053 | */ |
2054 | start_mm = &init_mm; | |
3fce371b | 2055 | mmget(&init_mm); |
1da177e4 LT |
2056 | |
2057 | /* | |
2058 | * Keep on scanning until all entries have gone. Usually, | |
2059 | * one pass through swap_map is enough, but not necessarily: | |
2060 | * there are races when an instance of an entry might be missed. | |
2061 | */ | |
38b5faf4 | 2062 | while ((i = find_next_to_unuse(si, i, frontswap)) != 0) { |
1da177e4 LT |
2063 | if (signal_pending(current)) { |
2064 | retval = -EINTR; | |
2065 | break; | |
2066 | } | |
2067 | ||
886bb7e9 | 2068 | /* |
1da177e4 LT |
2069 | * Get a page for the entry, using the existing swap |
2070 | * cache page if there is one. Otherwise, get a clean | |
886bb7e9 | 2071 | * page and read the swap into it. |
1da177e4 LT |
2072 | */ |
2073 | swap_map = &si->swap_map[i]; | |
2074 | entry = swp_entry(type, i); | |
02098fea | 2075 | page = read_swap_cache_async(entry, |
23955622 | 2076 | GFP_HIGHUSER_MOVABLE, NULL, 0, false); |
1da177e4 LT |
2077 | if (!page) { |
2078 | /* | |
2079 | * Either swap_duplicate() failed because entry | |
2080 | * has been freed independently, and will not be | |
2081 | * reused since sys_swapoff() already disabled | |
2082 | * allocation from here, or alloc_page() failed. | |
2083 | */ | |
edfe23da SL |
2084 | swcount = *swap_map; |
2085 | /* | |
2086 | * We don't hold lock here, so the swap entry could be | |
2087 | * SWAP_MAP_BAD (when the cluster is discarding). | |
2088 | * Instead of fail out, We can just skip the swap | |
2089 | * entry because swapoff will wait for discarding | |
2090 | * finish anyway. | |
2091 | */ | |
2092 | if (!swcount || swcount == SWAP_MAP_BAD) | |
1da177e4 LT |
2093 | continue; |
2094 | retval = -ENOMEM; | |
2095 | break; | |
2096 | } | |
2097 | ||
2098 | /* | |
2099 | * Don't hold on to start_mm if it looks like exiting. | |
2100 | */ | |
2101 | if (atomic_read(&start_mm->mm_users) == 1) { | |
2102 | mmput(start_mm); | |
2103 | start_mm = &init_mm; | |
3fce371b | 2104 | mmget(&init_mm); |
1da177e4 LT |
2105 | } |
2106 | ||
2107 | /* | |
2108 | * Wait for and lock page. When do_swap_page races with | |
2109 | * try_to_unuse, do_swap_page can handle the fault much | |
2110 | * faster than try_to_unuse can locate the entry. This | |
2111 | * apparently redundant "wait_on_page_locked" lets try_to_unuse | |
2112 | * defer to do_swap_page in such a case - in some tests, | |
2113 | * do_swap_page and try_to_unuse repeatedly compete. | |
2114 | */ | |
2115 | wait_on_page_locked(page); | |
2116 | wait_on_page_writeback(page); | |
2117 | lock_page(page); | |
2118 | wait_on_page_writeback(page); | |
2119 | ||
2120 | /* | |
2121 | * Remove all references to entry. | |
1da177e4 | 2122 | */ |
1da177e4 | 2123 | swcount = *swap_map; |
aaa46865 HD |
2124 | if (swap_count(swcount) == SWAP_MAP_SHMEM) { |
2125 | retval = shmem_unuse(entry, page); | |
2126 | /* page has already been unlocked and released */ | |
2127 | if (retval < 0) | |
2128 | break; | |
2129 | continue; | |
1da177e4 | 2130 | } |
aaa46865 HD |
2131 | if (swap_count(swcount) && start_mm != &init_mm) |
2132 | retval = unuse_mm(start_mm, entry, page); | |
2133 | ||
355cfa73 | 2134 | if (swap_count(*swap_map)) { |
1da177e4 LT |
2135 | int set_start_mm = (*swap_map >= swcount); |
2136 | struct list_head *p = &start_mm->mmlist; | |
2137 | struct mm_struct *new_start_mm = start_mm; | |
2138 | struct mm_struct *prev_mm = start_mm; | |
2139 | struct mm_struct *mm; | |
2140 | ||
3fce371b VN |
2141 | mmget(new_start_mm); |
2142 | mmget(prev_mm); | |
1da177e4 | 2143 | spin_lock(&mmlist_lock); |
aaa46865 | 2144 | while (swap_count(*swap_map) && !retval && |
1da177e4 LT |
2145 | (p = p->next) != &start_mm->mmlist) { |
2146 | mm = list_entry(p, struct mm_struct, mmlist); | |
388f7934 | 2147 | if (!mmget_not_zero(mm)) |
1da177e4 | 2148 | continue; |
1da177e4 LT |
2149 | spin_unlock(&mmlist_lock); |
2150 | mmput(prev_mm); | |
2151 | prev_mm = mm; | |
2152 | ||
2153 | cond_resched(); | |
2154 | ||
2155 | swcount = *swap_map; | |
355cfa73 | 2156 | if (!swap_count(swcount)) /* any usage ? */ |
1da177e4 | 2157 | ; |
aaa46865 | 2158 | else if (mm == &init_mm) |
1da177e4 | 2159 | set_start_mm = 1; |
aaa46865 | 2160 | else |
1da177e4 | 2161 | retval = unuse_mm(mm, entry, page); |
355cfa73 | 2162 | |
32c5fc10 | 2163 | if (set_start_mm && *swap_map < swcount) { |
1da177e4 | 2164 | mmput(new_start_mm); |
3fce371b | 2165 | mmget(mm); |
1da177e4 LT |
2166 | new_start_mm = mm; |
2167 | set_start_mm = 0; | |
2168 | } | |
2169 | spin_lock(&mmlist_lock); | |
2170 | } | |
2171 | spin_unlock(&mmlist_lock); | |
2172 | mmput(prev_mm); | |
2173 | mmput(start_mm); | |
2174 | start_mm = new_start_mm; | |
2175 | } | |
2176 | if (retval) { | |
2177 | unlock_page(page); | |
09cbfeaf | 2178 | put_page(page); |
1da177e4 LT |
2179 | break; |
2180 | } | |
2181 | ||
1da177e4 LT |
2182 | /* |
2183 | * If a reference remains (rare), we would like to leave | |
2184 | * the page in the swap cache; but try_to_unmap could | |
2185 | * then re-duplicate the entry once we drop page lock, | |
2186 | * so we might loop indefinitely; also, that page could | |
2187 | * not be swapped out to other storage meanwhile. So: | |
2188 | * delete from cache even if there's another reference, | |
2189 | * after ensuring that the data has been saved to disk - | |
2190 | * since if the reference remains (rarer), it will be | |
2191 | * read from disk into another page. Splitting into two | |
2192 | * pages would be incorrect if swap supported "shared | |
2193 | * private" pages, but they are handled by tmpfs files. | |
5ad64688 HD |
2194 | * |
2195 | * Given how unuse_vma() targets one particular offset | |
2196 | * in an anon_vma, once the anon_vma has been determined, | |
2197 | * this splitting happens to be just what is needed to | |
2198 | * handle where KSM pages have been swapped out: re-reading | |
2199 | * is unnecessarily slow, but we can fix that later on. | |
1da177e4 | 2200 | */ |
355cfa73 KH |
2201 | if (swap_count(*swap_map) && |
2202 | PageDirty(page) && PageSwapCache(page)) { | |
1da177e4 LT |
2203 | struct writeback_control wbc = { |
2204 | .sync_mode = WB_SYNC_NONE, | |
2205 | }; | |
2206 | ||
e0709829 | 2207 | swap_writepage(compound_head(page), &wbc); |
1da177e4 LT |
2208 | lock_page(page); |
2209 | wait_on_page_writeback(page); | |
2210 | } | |
68bdc8d6 HD |
2211 | |
2212 | /* | |
2213 | * It is conceivable that a racing task removed this page from | |
2214 | * swap cache just before we acquired the page lock at the top, | |
2215 | * or while we dropped it in unuse_mm(). The page might even | |
2216 | * be back in swap cache on another swap area: that we must not | |
2217 | * delete, since it may not have been written out to swap yet. | |
2218 | */ | |
2219 | if (PageSwapCache(page) && | |
e0709829 HY |
2220 | likely(page_private(page) == entry.val) && |
2221 | !page_swapped(page)) | |
2222 | delete_from_swap_cache(compound_head(page)); | |
1da177e4 LT |
2223 | |
2224 | /* | |
2225 | * So we could skip searching mms once swap count went | |
2226 | * to 1, we did not mark any present ptes as dirty: must | |
2706a1b8 | 2227 | * mark page dirty so shrink_page_list will preserve it. |
1da177e4 LT |
2228 | */ |
2229 | SetPageDirty(page); | |
2230 | unlock_page(page); | |
09cbfeaf | 2231 | put_page(page); |
1da177e4 LT |
2232 | |
2233 | /* | |
2234 | * Make sure that we aren't completely killing | |
2235 | * interactive performance. | |
2236 | */ | |
2237 | cond_resched(); | |
38b5faf4 DM |
2238 | if (frontswap && pages_to_unuse > 0) { |
2239 | if (!--pages_to_unuse) | |
2240 | break; | |
2241 | } | |
1da177e4 LT |
2242 | } |
2243 | ||
2244 | mmput(start_mm); | |
1da177e4 LT |
2245 | return retval; |
2246 | } | |
2247 | ||
2248 | /* | |
5d337b91 HD |
2249 | * After a successful try_to_unuse, if no swap is now in use, we know |
2250 | * we can empty the mmlist. swap_lock must be held on entry and exit. | |
2251 | * Note that mmlist_lock nests inside swap_lock, and an mm must be | |
1da177e4 LT |
2252 | * added to the mmlist just after page_duplicate - before would be racy. |
2253 | */ | |
2254 | static void drain_mmlist(void) | |
2255 | { | |
2256 | struct list_head *p, *next; | |
efa90a98 | 2257 | unsigned int type; |
1da177e4 | 2258 | |
efa90a98 HD |
2259 | for (type = 0; type < nr_swapfiles; type++) |
2260 | if (swap_info[type]->inuse_pages) | |
1da177e4 LT |
2261 | return; |
2262 | spin_lock(&mmlist_lock); | |
2263 | list_for_each_safe(p, next, &init_mm.mmlist) | |
2264 | list_del_init(p); | |
2265 | spin_unlock(&mmlist_lock); | |
2266 | } | |
2267 | ||
2268 | /* | |
2269 | * Use this swapdev's extent info to locate the (PAGE_SIZE) block which | |
d4906e1a LS |
2270 | * corresponds to page offset for the specified swap entry. |
2271 | * Note that the type of this function is sector_t, but it returns page offset | |
2272 | * into the bdev, not sector offset. | |
1da177e4 | 2273 | */ |
d4906e1a | 2274 | static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev) |
1da177e4 | 2275 | { |
f29ad6a9 HD |
2276 | struct swap_info_struct *sis; |
2277 | struct swap_extent *start_se; | |
2278 | struct swap_extent *se; | |
2279 | pgoff_t offset; | |
2280 | ||
efa90a98 | 2281 | sis = swap_info[swp_type(entry)]; |
f29ad6a9 HD |
2282 | *bdev = sis->bdev; |
2283 | ||
2284 | offset = swp_offset(entry); | |
2285 | start_se = sis->curr_swap_extent; | |
2286 | se = start_se; | |
1da177e4 LT |
2287 | |
2288 | for ( ; ; ) { | |
1da177e4 LT |
2289 | if (se->start_page <= offset && |
2290 | offset < (se->start_page + se->nr_pages)) { | |
2291 | return se->start_block + (offset - se->start_page); | |
2292 | } | |
a8ae4991 | 2293 | se = list_next_entry(se, list); |
1da177e4 LT |
2294 | sis->curr_swap_extent = se; |
2295 | BUG_ON(se == start_se); /* It *must* be present */ | |
2296 | } | |
2297 | } | |
2298 | ||
d4906e1a LS |
2299 | /* |
2300 | * Returns the page offset into bdev for the specified page's swap entry. | |
2301 | */ | |
2302 | sector_t map_swap_page(struct page *page, struct block_device **bdev) | |
2303 | { | |
2304 | swp_entry_t entry; | |
2305 | entry.val = page_private(page); | |
2306 | return map_swap_entry(entry, bdev); | |
2307 | } | |
2308 | ||
1da177e4 LT |
2309 | /* |
2310 | * Free all of a swapdev's extent information | |
2311 | */ | |
2312 | static void destroy_swap_extents(struct swap_info_struct *sis) | |
2313 | { | |
9625a5f2 | 2314 | while (!list_empty(&sis->first_swap_extent.list)) { |
1da177e4 LT |
2315 | struct swap_extent *se; |
2316 | ||
a8ae4991 | 2317 | se = list_first_entry(&sis->first_swap_extent.list, |
1da177e4 LT |
2318 | struct swap_extent, list); |
2319 | list_del(&se->list); | |
2320 | kfree(se); | |
2321 | } | |
62c230bc MG |
2322 | |
2323 | if (sis->flags & SWP_FILE) { | |
2324 | struct file *swap_file = sis->swap_file; | |
2325 | struct address_space *mapping = swap_file->f_mapping; | |
2326 | ||
2327 | sis->flags &= ~SWP_FILE; | |
2328 | mapping->a_ops->swap_deactivate(swap_file); | |
2329 | } | |
1da177e4 LT |
2330 | } |
2331 | ||
2332 | /* | |
2333 | * Add a block range (and the corresponding page range) into this swapdev's | |
11d31886 | 2334 | * extent list. The extent list is kept sorted in page order. |
1da177e4 | 2335 | * |
11d31886 | 2336 | * This function rather assumes that it is called in ascending page order. |
1da177e4 | 2337 | */ |
a509bc1a | 2338 | int |
1da177e4 LT |
2339 | add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, |
2340 | unsigned long nr_pages, sector_t start_block) | |
2341 | { | |
2342 | struct swap_extent *se; | |
2343 | struct swap_extent *new_se; | |
2344 | struct list_head *lh; | |
2345 | ||
9625a5f2 HD |
2346 | if (start_page == 0) { |
2347 | se = &sis->first_swap_extent; | |
2348 | sis->curr_swap_extent = se; | |
2349 | se->start_page = 0; | |
2350 | se->nr_pages = nr_pages; | |
2351 | se->start_block = start_block; | |
2352 | return 1; | |
2353 | } else { | |
2354 | lh = sis->first_swap_extent.list.prev; /* Highest extent */ | |
1da177e4 | 2355 | se = list_entry(lh, struct swap_extent, list); |
11d31886 HD |
2356 | BUG_ON(se->start_page + se->nr_pages != start_page); |
2357 | if (se->start_block + se->nr_pages == start_block) { | |
1da177e4 LT |
2358 | /* Merge it */ |
2359 | se->nr_pages += nr_pages; | |
2360 | return 0; | |
2361 | } | |
1da177e4 LT |
2362 | } |
2363 | ||
2364 | /* | |
2365 | * No merge. Insert a new extent, preserving ordering. | |
2366 | */ | |
2367 | new_se = kmalloc(sizeof(*se), GFP_KERNEL); | |
2368 | if (new_se == NULL) | |
2369 | return -ENOMEM; | |
2370 | new_se->start_page = start_page; | |
2371 | new_se->nr_pages = nr_pages; | |
2372 | new_se->start_block = start_block; | |
2373 | ||
9625a5f2 | 2374 | list_add_tail(&new_se->list, &sis->first_swap_extent.list); |
53092a74 | 2375 | return 1; |
1da177e4 LT |
2376 | } |
2377 | ||
2378 | /* | |
2379 | * A `swap extent' is a simple thing which maps a contiguous range of pages | |
2380 | * onto a contiguous range of disk blocks. An ordered list of swap extents | |
2381 | * is built at swapon time and is then used at swap_writepage/swap_readpage | |
2382 | * time for locating where on disk a page belongs. | |
2383 | * | |
2384 | * If the swapfile is an S_ISBLK block device, a single extent is installed. | |
2385 | * This is done so that the main operating code can treat S_ISBLK and S_ISREG | |
2386 | * swap files identically. | |
2387 | * | |
2388 | * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap | |
2389 | * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK | |
2390 | * swapfiles are handled *identically* after swapon time. | |
2391 | * | |
2392 | * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks | |
2393 | * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If | |
2394 | * some stray blocks are found which do not fall within the PAGE_SIZE alignment | |
2395 | * requirements, they are simply tossed out - we will never use those blocks | |
2396 | * for swapping. | |
2397 | * | |
b0d9bcd4 | 2398 | * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This |
1da177e4 LT |
2399 | * prevents root from shooting her foot off by ftruncating an in-use swapfile, |
2400 | * which will scribble on the fs. | |
2401 | * | |
2402 | * The amount of disk space which a single swap extent represents varies. | |
2403 | * Typically it is in the 1-4 megabyte range. So we can have hundreds of | |
2404 | * extents in the list. To avoid much list walking, we cache the previous | |
2405 | * search location in `curr_swap_extent', and start new searches from there. | |
2406 | * This is extremely effective. The average number of iterations in | |
2407 | * map_swap_page() has been measured at about 0.3 per page. - akpm. | |
2408 | */ | |
53092a74 | 2409 | static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
1da177e4 | 2410 | { |
62c230bc MG |
2411 | struct file *swap_file = sis->swap_file; |
2412 | struct address_space *mapping = swap_file->f_mapping; | |
2413 | struct inode *inode = mapping->host; | |
1da177e4 LT |
2414 | int ret; |
2415 | ||
1da177e4 LT |
2416 | if (S_ISBLK(inode->i_mode)) { |
2417 | ret = add_swap_extent(sis, 0, sis->max, 0); | |
53092a74 | 2418 | *span = sis->pages; |
a509bc1a | 2419 | return ret; |
1da177e4 LT |
2420 | } |
2421 | ||
62c230bc | 2422 | if (mapping->a_ops->swap_activate) { |
a509bc1a | 2423 | ret = mapping->a_ops->swap_activate(sis, swap_file, span); |
62c230bc MG |
2424 | if (!ret) { |
2425 | sis->flags |= SWP_FILE; | |
2426 | ret = add_swap_extent(sis, 0, sis->max, 0); | |
2427 | *span = sis->pages; | |
2428 | } | |
a509bc1a | 2429 | return ret; |
62c230bc MG |
2430 | } |
2431 | ||
a509bc1a | 2432 | return generic_swapfile_activate(sis, swap_file, span); |
1da177e4 LT |
2433 | } |
2434 | ||
a2468cc9 AL |
2435 | static int swap_node(struct swap_info_struct *p) |
2436 | { | |
2437 | struct block_device *bdev; | |
2438 | ||
2439 | if (p->bdev) | |
2440 | bdev = p->bdev; | |
2441 | else | |
2442 | bdev = p->swap_file->f_inode->i_sb->s_bdev; | |
2443 | ||
2444 | return bdev ? bdev->bd_disk->node_id : NUMA_NO_NODE; | |
2445 | } | |
2446 | ||
cf0cac0a | 2447 | static void _enable_swap_info(struct swap_info_struct *p, int prio, |
2a8f9449 SL |
2448 | unsigned char *swap_map, |
2449 | struct swap_cluster_info *cluster_info) | |
40531542 | 2450 | { |
a2468cc9 AL |
2451 | int i; |
2452 | ||
40531542 CEB |
2453 | if (prio >= 0) |
2454 | p->prio = prio; | |
2455 | else | |
2456 | p->prio = --least_priority; | |
18ab4d4c DS |
2457 | /* |
2458 | * the plist prio is negated because plist ordering is | |
2459 | * low-to-high, while swap ordering is high-to-low | |
2460 | */ | |
2461 | p->list.prio = -p->prio; | |
a2468cc9 AL |
2462 | for_each_node(i) { |
2463 | if (p->prio >= 0) | |
2464 | p->avail_lists[i].prio = -p->prio; | |
2465 | else { | |
2466 | if (swap_node(p) == i) | |
2467 | p->avail_lists[i].prio = 1; | |
2468 | else | |
2469 | p->avail_lists[i].prio = -p->prio; | |
2470 | } | |
2471 | } | |
40531542 | 2472 | p->swap_map = swap_map; |
2a8f9449 | 2473 | p->cluster_info = cluster_info; |
40531542 | 2474 | p->flags |= SWP_WRITEOK; |
ec8acf20 | 2475 | atomic_long_add(p->pages, &nr_swap_pages); |
40531542 CEB |
2476 | total_swap_pages += p->pages; |
2477 | ||
adfab836 | 2478 | assert_spin_locked(&swap_lock); |
adfab836 | 2479 | /* |
18ab4d4c DS |
2480 | * both lists are plists, and thus priority ordered. |
2481 | * swap_active_head needs to be priority ordered for swapoff(), | |
2482 | * which on removal of any swap_info_struct with an auto-assigned | |
2483 | * (i.e. negative) priority increments the auto-assigned priority | |
2484 | * of any lower-priority swap_info_structs. | |
2485 | * swap_avail_head needs to be priority ordered for get_swap_page(), | |
2486 | * which allocates swap pages from the highest available priority | |
2487 | * swap_info_struct. | |
adfab836 | 2488 | */ |
18ab4d4c | 2489 | plist_add(&p->list, &swap_active_head); |
a2468cc9 | 2490 | add_to_avail_list(p); |
cf0cac0a CEB |
2491 | } |
2492 | ||
2493 | static void enable_swap_info(struct swap_info_struct *p, int prio, | |
2494 | unsigned char *swap_map, | |
2a8f9449 | 2495 | struct swap_cluster_info *cluster_info, |
cf0cac0a CEB |
2496 | unsigned long *frontswap_map) |
2497 | { | |
4f89849d | 2498 | frontswap_init(p->type, frontswap_map); |
cf0cac0a | 2499 | spin_lock(&swap_lock); |
ec8acf20 | 2500 | spin_lock(&p->lock); |
2a8f9449 | 2501 | _enable_swap_info(p, prio, swap_map, cluster_info); |
ec8acf20 | 2502 | spin_unlock(&p->lock); |
cf0cac0a CEB |
2503 | spin_unlock(&swap_lock); |
2504 | } | |
2505 | ||
2506 | static void reinsert_swap_info(struct swap_info_struct *p) | |
2507 | { | |
2508 | spin_lock(&swap_lock); | |
ec8acf20 | 2509 | spin_lock(&p->lock); |
2a8f9449 | 2510 | _enable_swap_info(p, p->prio, p->swap_map, p->cluster_info); |
ec8acf20 | 2511 | spin_unlock(&p->lock); |
40531542 CEB |
2512 | spin_unlock(&swap_lock); |
2513 | } | |
2514 | ||
67afa38e TC |
2515 | bool has_usable_swap(void) |
2516 | { | |
2517 | bool ret = true; | |
2518 | ||
2519 | spin_lock(&swap_lock); | |
2520 | if (plist_head_empty(&swap_active_head)) | |
2521 | ret = false; | |
2522 | spin_unlock(&swap_lock); | |
2523 | return ret; | |
2524 | } | |
2525 | ||
c4ea37c2 | 2526 | SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) |
1da177e4 | 2527 | { |
73c34b6a | 2528 | struct swap_info_struct *p = NULL; |
8d69aaee | 2529 | unsigned char *swap_map; |
2a8f9449 | 2530 | struct swap_cluster_info *cluster_info; |
4f89849d | 2531 | unsigned long *frontswap_map; |
1da177e4 LT |
2532 | struct file *swap_file, *victim; |
2533 | struct address_space *mapping; | |
2534 | struct inode *inode; | |
91a27b2a | 2535 | struct filename *pathname; |
adfab836 | 2536 | int err, found = 0; |
5b808a23 | 2537 | unsigned int old_block_size; |
886bb7e9 | 2538 | |
1da177e4 LT |
2539 | if (!capable(CAP_SYS_ADMIN)) |
2540 | return -EPERM; | |
2541 | ||
191c5424 AV |
2542 | BUG_ON(!current->mm); |
2543 | ||
1da177e4 | 2544 | pathname = getname(specialfile); |
1da177e4 | 2545 | if (IS_ERR(pathname)) |
f58b59c1 | 2546 | return PTR_ERR(pathname); |
1da177e4 | 2547 | |
669abf4e | 2548 | victim = file_open_name(pathname, O_RDWR|O_LARGEFILE, 0); |
1da177e4 LT |
2549 | err = PTR_ERR(victim); |
2550 | if (IS_ERR(victim)) | |
2551 | goto out; | |
2552 | ||
2553 | mapping = victim->f_mapping; | |
5d337b91 | 2554 | spin_lock(&swap_lock); |
18ab4d4c | 2555 | plist_for_each_entry(p, &swap_active_head, list) { |
22c6f8fd | 2556 | if (p->flags & SWP_WRITEOK) { |
adfab836 DS |
2557 | if (p->swap_file->f_mapping == mapping) { |
2558 | found = 1; | |
1da177e4 | 2559 | break; |
adfab836 | 2560 | } |
1da177e4 | 2561 | } |
1da177e4 | 2562 | } |
adfab836 | 2563 | if (!found) { |
1da177e4 | 2564 | err = -EINVAL; |
5d337b91 | 2565 | spin_unlock(&swap_lock); |
1da177e4 LT |
2566 | goto out_dput; |
2567 | } | |
191c5424 | 2568 | if (!security_vm_enough_memory_mm(current->mm, p->pages)) |
1da177e4 LT |
2569 | vm_unacct_memory(p->pages); |
2570 | else { | |
2571 | err = -ENOMEM; | |
5d337b91 | 2572 | spin_unlock(&swap_lock); |
1da177e4 LT |
2573 | goto out_dput; |
2574 | } | |
a2468cc9 | 2575 | del_from_avail_list(p); |
ec8acf20 | 2576 | spin_lock(&p->lock); |
78ecba08 | 2577 | if (p->prio < 0) { |
adfab836 | 2578 | struct swap_info_struct *si = p; |
a2468cc9 | 2579 | int nid; |
adfab836 | 2580 | |
18ab4d4c | 2581 | plist_for_each_entry_continue(si, &swap_active_head, list) { |
adfab836 | 2582 | si->prio++; |
18ab4d4c | 2583 | si->list.prio--; |
a2468cc9 AL |
2584 | for_each_node(nid) { |
2585 | if (si->avail_lists[nid].prio != 1) | |
2586 | si->avail_lists[nid].prio--; | |
2587 | } | |
adfab836 | 2588 | } |
78ecba08 HD |
2589 | least_priority++; |
2590 | } | |
18ab4d4c | 2591 | plist_del(&p->list, &swap_active_head); |
ec8acf20 | 2592 | atomic_long_sub(p->pages, &nr_swap_pages); |
1da177e4 LT |
2593 | total_swap_pages -= p->pages; |
2594 | p->flags &= ~SWP_WRITEOK; | |
ec8acf20 | 2595 | spin_unlock(&p->lock); |
5d337b91 | 2596 | spin_unlock(&swap_lock); |
fb4f88dc | 2597 | |
039939a6 TC |
2598 | disable_swap_slots_cache_lock(); |
2599 | ||
e1e12d2f | 2600 | set_current_oom_origin(); |
adfab836 | 2601 | err = try_to_unuse(p->type, false, 0); /* force unuse all pages */ |
e1e12d2f | 2602 | clear_current_oom_origin(); |
1da177e4 | 2603 | |
1da177e4 LT |
2604 | if (err) { |
2605 | /* re-insert swap space back into swap_list */ | |
cf0cac0a | 2606 | reinsert_swap_info(p); |
039939a6 | 2607 | reenable_swap_slots_cache_unlock(); |
1da177e4 LT |
2608 | goto out_dput; |
2609 | } | |
52b7efdb | 2610 | |
039939a6 TC |
2611 | reenable_swap_slots_cache_unlock(); |
2612 | ||
815c2c54 SL |
2613 | flush_work(&p->discard_work); |
2614 | ||
5d337b91 | 2615 | destroy_swap_extents(p); |
570a335b HD |
2616 | if (p->flags & SWP_CONTINUED) |
2617 | free_swap_count_continuations(p); | |
2618 | ||
81a0298b HY |
2619 | if (!p->bdev || !blk_queue_nonrot(bdev_get_queue(p->bdev))) |
2620 | atomic_dec(&nr_rotate_swap); | |
2621 | ||
fc0abb14 | 2622 | mutex_lock(&swapon_mutex); |
5d337b91 | 2623 | spin_lock(&swap_lock); |
ec8acf20 | 2624 | spin_lock(&p->lock); |
5d337b91 HD |
2625 | drain_mmlist(); |
2626 | ||
52b7efdb | 2627 | /* wait for anyone still in scan_swap_map */ |
52b7efdb HD |
2628 | p->highest_bit = 0; /* cuts scans short */ |
2629 | while (p->flags >= SWP_SCANNING) { | |
ec8acf20 | 2630 | spin_unlock(&p->lock); |
5d337b91 | 2631 | spin_unlock(&swap_lock); |
13e4b57f | 2632 | schedule_timeout_uninterruptible(1); |
5d337b91 | 2633 | spin_lock(&swap_lock); |
ec8acf20 | 2634 | spin_lock(&p->lock); |
52b7efdb | 2635 | } |
52b7efdb | 2636 | |
1da177e4 | 2637 | swap_file = p->swap_file; |
5b808a23 | 2638 | old_block_size = p->old_block_size; |
1da177e4 LT |
2639 | p->swap_file = NULL; |
2640 | p->max = 0; | |
2641 | swap_map = p->swap_map; | |
2642 | p->swap_map = NULL; | |
2a8f9449 SL |
2643 | cluster_info = p->cluster_info; |
2644 | p->cluster_info = NULL; | |
4f89849d | 2645 | frontswap_map = frontswap_map_get(p); |
ec8acf20 | 2646 | spin_unlock(&p->lock); |
5d337b91 | 2647 | spin_unlock(&swap_lock); |
adfab836 | 2648 | frontswap_invalidate_area(p->type); |
58e97ba6 | 2649 | frontswap_map_set(p, NULL); |
fc0abb14 | 2650 | mutex_unlock(&swapon_mutex); |
ebc2a1a6 SL |
2651 | free_percpu(p->percpu_cluster); |
2652 | p->percpu_cluster = NULL; | |
1da177e4 | 2653 | vfree(swap_map); |
54f180d3 HY |
2654 | kvfree(cluster_info); |
2655 | kvfree(frontswap_map); | |
2de1a7e4 | 2656 | /* Destroy swap account information */ |
adfab836 | 2657 | swap_cgroup_swapoff(p->type); |
4b3ef9da | 2658 | exit_swap_address_space(p->type); |
27a7faa0 | 2659 | |
1da177e4 LT |
2660 | inode = mapping->host; |
2661 | if (S_ISBLK(inode->i_mode)) { | |
2662 | struct block_device *bdev = I_BDEV(inode); | |
5b808a23 | 2663 | set_blocksize(bdev, old_block_size); |
e525fd89 | 2664 | blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); |
1da177e4 | 2665 | } else { |
5955102c | 2666 | inode_lock(inode); |
1da177e4 | 2667 | inode->i_flags &= ~S_SWAPFILE; |
5955102c | 2668 | inode_unlock(inode); |
1da177e4 LT |
2669 | } |
2670 | filp_close(swap_file, NULL); | |
f893ab41 WY |
2671 | |
2672 | /* | |
2673 | * Clear the SWP_USED flag after all resources are freed so that swapon | |
2674 | * can reuse this swap_info in alloc_swap_info() safely. It is ok to | |
2675 | * not hold p->lock after we cleared its SWP_WRITEOK. | |
2676 | */ | |
2677 | spin_lock(&swap_lock); | |
2678 | p->flags = 0; | |
2679 | spin_unlock(&swap_lock); | |
2680 | ||
1da177e4 | 2681 | err = 0; |
66d7dd51 KS |
2682 | atomic_inc(&proc_poll_event); |
2683 | wake_up_interruptible(&proc_poll_wait); | |
1da177e4 LT |
2684 | |
2685 | out_dput: | |
2686 | filp_close(victim, NULL); | |
2687 | out: | |
f58b59c1 | 2688 | putname(pathname); |
1da177e4 LT |
2689 | return err; |
2690 | } | |
2691 | ||
2692 | #ifdef CONFIG_PROC_FS | |
66d7dd51 KS |
2693 | static unsigned swaps_poll(struct file *file, poll_table *wait) |
2694 | { | |
f1514638 | 2695 | struct seq_file *seq = file->private_data; |
66d7dd51 KS |
2696 | |
2697 | poll_wait(file, &proc_poll_wait, wait); | |
2698 | ||
f1514638 KS |
2699 | if (seq->poll_event != atomic_read(&proc_poll_event)) { |
2700 | seq->poll_event = atomic_read(&proc_poll_event); | |
66d7dd51 KS |
2701 | return POLLIN | POLLRDNORM | POLLERR | POLLPRI; |
2702 | } | |
2703 | ||
2704 | return POLLIN | POLLRDNORM; | |
2705 | } | |
2706 | ||
1da177e4 LT |
2707 | /* iterator */ |
2708 | static void *swap_start(struct seq_file *swap, loff_t *pos) | |
2709 | { | |
efa90a98 HD |
2710 | struct swap_info_struct *si; |
2711 | int type; | |
1da177e4 LT |
2712 | loff_t l = *pos; |
2713 | ||
fc0abb14 | 2714 | mutex_lock(&swapon_mutex); |
1da177e4 | 2715 | |
881e4aab SS |
2716 | if (!l) |
2717 | return SEQ_START_TOKEN; | |
2718 | ||
efa90a98 HD |
2719 | for (type = 0; type < nr_swapfiles; type++) { |
2720 | smp_rmb(); /* read nr_swapfiles before swap_info[type] */ | |
2721 | si = swap_info[type]; | |
2722 | if (!(si->flags & SWP_USED) || !si->swap_map) | |
1da177e4 | 2723 | continue; |
881e4aab | 2724 | if (!--l) |
efa90a98 | 2725 | return si; |
1da177e4 LT |
2726 | } |
2727 | ||
2728 | return NULL; | |
2729 | } | |
2730 | ||
2731 | static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) | |
2732 | { | |
efa90a98 HD |
2733 | struct swap_info_struct *si = v; |
2734 | int type; | |
1da177e4 | 2735 | |
881e4aab | 2736 | if (v == SEQ_START_TOKEN) |
efa90a98 HD |
2737 | type = 0; |
2738 | else | |
2739 | type = si->type + 1; | |
881e4aab | 2740 | |
efa90a98 HD |
2741 | for (; type < nr_swapfiles; type++) { |
2742 | smp_rmb(); /* read nr_swapfiles before swap_info[type] */ | |
2743 | si = swap_info[type]; | |
2744 | if (!(si->flags & SWP_USED) || !si->swap_map) | |
1da177e4 LT |
2745 | continue; |
2746 | ++*pos; | |
efa90a98 | 2747 | return si; |
1da177e4 LT |
2748 | } |
2749 | ||
2750 | return NULL; | |
2751 | } | |
2752 | ||
2753 | static void swap_stop(struct seq_file *swap, void *v) | |
2754 | { | |
fc0abb14 | 2755 | mutex_unlock(&swapon_mutex); |
1da177e4 LT |
2756 | } |
2757 | ||
2758 | static int swap_show(struct seq_file *swap, void *v) | |
2759 | { | |
efa90a98 | 2760 | struct swap_info_struct *si = v; |
1da177e4 LT |
2761 | struct file *file; |
2762 | int len; | |
2763 | ||
efa90a98 | 2764 | if (si == SEQ_START_TOKEN) { |
881e4aab SS |
2765 | seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n"); |
2766 | return 0; | |
2767 | } | |
1da177e4 | 2768 | |
efa90a98 | 2769 | file = si->swap_file; |
2726d566 | 2770 | len = seq_file_path(swap, file, " \t\n\\"); |
6eb396dc | 2771 | seq_printf(swap, "%*s%s\t%u\t%u\t%d\n", |
886bb7e9 | 2772 | len < 40 ? 40 - len : 1, " ", |
496ad9aa | 2773 | S_ISBLK(file_inode(file)->i_mode) ? |
1da177e4 | 2774 | "partition" : "file\t", |
efa90a98 HD |
2775 | si->pages << (PAGE_SHIFT - 10), |
2776 | si->inuse_pages << (PAGE_SHIFT - 10), | |
2777 | si->prio); | |
1da177e4 LT |
2778 | return 0; |
2779 | } | |
2780 | ||
15ad7cdc | 2781 | static const struct seq_operations swaps_op = { |
1da177e4 LT |
2782 | .start = swap_start, |
2783 | .next = swap_next, | |
2784 | .stop = swap_stop, | |
2785 | .show = swap_show | |
2786 | }; | |
2787 | ||
2788 | static int swaps_open(struct inode *inode, struct file *file) | |
2789 | { | |
f1514638 | 2790 | struct seq_file *seq; |
66d7dd51 KS |
2791 | int ret; |
2792 | ||
66d7dd51 | 2793 | ret = seq_open(file, &swaps_op); |
f1514638 | 2794 | if (ret) |
66d7dd51 | 2795 | return ret; |
66d7dd51 | 2796 | |
f1514638 KS |
2797 | seq = file->private_data; |
2798 | seq->poll_event = atomic_read(&proc_poll_event); | |
2799 | return 0; | |
1da177e4 LT |
2800 | } |
2801 | ||
15ad7cdc | 2802 | static const struct file_operations proc_swaps_operations = { |
1da177e4 LT |
2803 | .open = swaps_open, |
2804 | .read = seq_read, | |
2805 | .llseek = seq_lseek, | |
2806 | .release = seq_release, | |
66d7dd51 | 2807 | .poll = swaps_poll, |
1da177e4 LT |
2808 | }; |
2809 | ||
2810 | static int __init procswaps_init(void) | |
2811 | { | |
3d71f86f | 2812 | proc_create("swaps", 0, NULL, &proc_swaps_operations); |
1da177e4 LT |
2813 | return 0; |
2814 | } | |
2815 | __initcall(procswaps_init); | |
2816 | #endif /* CONFIG_PROC_FS */ | |
2817 | ||
1796316a JB |
2818 | #ifdef MAX_SWAPFILES_CHECK |
2819 | static int __init max_swapfiles_check(void) | |
2820 | { | |
2821 | MAX_SWAPFILES_CHECK(); | |
2822 | return 0; | |
2823 | } | |
2824 | late_initcall(max_swapfiles_check); | |
2825 | #endif | |
2826 | ||
53cbb243 | 2827 | static struct swap_info_struct *alloc_swap_info(void) |
1da177e4 | 2828 | { |
73c34b6a | 2829 | struct swap_info_struct *p; |
1da177e4 | 2830 | unsigned int type; |
a2468cc9 | 2831 | int i; |
efa90a98 HD |
2832 | |
2833 | p = kzalloc(sizeof(*p), GFP_KERNEL); | |
2834 | if (!p) | |
53cbb243 | 2835 | return ERR_PTR(-ENOMEM); |
efa90a98 | 2836 | |
5d337b91 | 2837 | spin_lock(&swap_lock); |
efa90a98 HD |
2838 | for (type = 0; type < nr_swapfiles; type++) { |
2839 | if (!(swap_info[type]->flags & SWP_USED)) | |
1da177e4 | 2840 | break; |
efa90a98 | 2841 | } |
0697212a | 2842 | if (type >= MAX_SWAPFILES) { |
5d337b91 | 2843 | spin_unlock(&swap_lock); |
efa90a98 | 2844 | kfree(p); |
730c0581 | 2845 | return ERR_PTR(-EPERM); |
1da177e4 | 2846 | } |
efa90a98 HD |
2847 | if (type >= nr_swapfiles) { |
2848 | p->type = type; | |
2849 | swap_info[type] = p; | |
2850 | /* | |
2851 | * Write swap_info[type] before nr_swapfiles, in case a | |
2852 | * racing procfs swap_start() or swap_next() is reading them. | |
2853 | * (We never shrink nr_swapfiles, we never free this entry.) | |
2854 | */ | |
2855 | smp_wmb(); | |
2856 | nr_swapfiles++; | |
2857 | } else { | |
2858 | kfree(p); | |
2859 | p = swap_info[type]; | |
2860 | /* | |
2861 | * Do not memset this entry: a racing procfs swap_next() | |
2862 | * would be relying on p->type to remain valid. | |
2863 | */ | |
2864 | } | |
9625a5f2 | 2865 | INIT_LIST_HEAD(&p->first_swap_extent.list); |
18ab4d4c | 2866 | plist_node_init(&p->list, 0); |
a2468cc9 AL |
2867 | for_each_node(i) |
2868 | plist_node_init(&p->avail_lists[i], 0); | |
1da177e4 | 2869 | p->flags = SWP_USED; |
5d337b91 | 2870 | spin_unlock(&swap_lock); |
ec8acf20 | 2871 | spin_lock_init(&p->lock); |
2628bd6f | 2872 | spin_lock_init(&p->cont_lock); |
efa90a98 | 2873 | |
53cbb243 | 2874 | return p; |
53cbb243 CEB |
2875 | } |
2876 | ||
4d0e1e10 CEB |
2877 | static int claim_swapfile(struct swap_info_struct *p, struct inode *inode) |
2878 | { | |
2879 | int error; | |
2880 | ||
2881 | if (S_ISBLK(inode->i_mode)) { | |
2882 | p->bdev = bdgrab(I_BDEV(inode)); | |
2883 | error = blkdev_get(p->bdev, | |
6f179af8 | 2884 | FMODE_READ | FMODE_WRITE | FMODE_EXCL, p); |
4d0e1e10 CEB |
2885 | if (error < 0) { |
2886 | p->bdev = NULL; | |
6f179af8 | 2887 | return error; |
4d0e1e10 CEB |
2888 | } |
2889 | p->old_block_size = block_size(p->bdev); | |
2890 | error = set_blocksize(p->bdev, PAGE_SIZE); | |
2891 | if (error < 0) | |
87ade72a | 2892 | return error; |
4d0e1e10 CEB |
2893 | p->flags |= SWP_BLKDEV; |
2894 | } else if (S_ISREG(inode->i_mode)) { | |
2895 | p->bdev = inode->i_sb->s_bdev; | |
5955102c | 2896 | inode_lock(inode); |
87ade72a CEB |
2897 | if (IS_SWAPFILE(inode)) |
2898 | return -EBUSY; | |
2899 | } else | |
2900 | return -EINVAL; | |
4d0e1e10 CEB |
2901 | |
2902 | return 0; | |
4d0e1e10 CEB |
2903 | } |
2904 | ||
ca8bd38b CEB |
2905 | static unsigned long read_swap_header(struct swap_info_struct *p, |
2906 | union swap_header *swap_header, | |
2907 | struct inode *inode) | |
2908 | { | |
2909 | int i; | |
2910 | unsigned long maxpages; | |
2911 | unsigned long swapfilepages; | |
d6bbbd29 | 2912 | unsigned long last_page; |
ca8bd38b CEB |
2913 | |
2914 | if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) { | |
465c47fd | 2915 | pr_err("Unable to find swap-space signature\n"); |
38719025 | 2916 | return 0; |
ca8bd38b CEB |
2917 | } |
2918 | ||
2919 | /* swap partition endianess hack... */ | |
2920 | if (swab32(swap_header->info.version) == 1) { | |
2921 | swab32s(&swap_header->info.version); | |
2922 | swab32s(&swap_header->info.last_page); | |
2923 | swab32s(&swap_header->info.nr_badpages); | |
dd111be6 JH |
2924 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
2925 | return 0; | |
ca8bd38b CEB |
2926 | for (i = 0; i < swap_header->info.nr_badpages; i++) |
2927 | swab32s(&swap_header->info.badpages[i]); | |
2928 | } | |
2929 | /* Check the swap header's sub-version */ | |
2930 | if (swap_header->info.version != 1) { | |
465c47fd AM |
2931 | pr_warn("Unable to handle swap header version %d\n", |
2932 | swap_header->info.version); | |
38719025 | 2933 | return 0; |
ca8bd38b CEB |
2934 | } |
2935 | ||
2936 | p->lowest_bit = 1; | |
2937 | p->cluster_next = 1; | |
2938 | p->cluster_nr = 0; | |
2939 | ||
2940 | /* | |
2941 | * Find out how many pages are allowed for a single swap | |
9b15b817 | 2942 | * device. There are two limiting factors: 1) the number |
a2c16d6c HD |
2943 | * of bits for the swap offset in the swp_entry_t type, and |
2944 | * 2) the number of bits in the swap pte as defined by the | |
9b15b817 | 2945 | * different architectures. In order to find the |
a2c16d6c | 2946 | * largest possible bit mask, a swap entry with swap type 0 |
ca8bd38b | 2947 | * and swap offset ~0UL is created, encoded to a swap pte, |
a2c16d6c | 2948 | * decoded to a swp_entry_t again, and finally the swap |
ca8bd38b CEB |
2949 | * offset is extracted. This will mask all the bits from |
2950 | * the initial ~0UL mask that can't be encoded in either | |
2951 | * the swp_entry_t or the architecture definition of a | |
9b15b817 | 2952 | * swap pte. |
ca8bd38b CEB |
2953 | */ |
2954 | maxpages = swp_offset(pte_to_swp_entry( | |
9b15b817 | 2955 | swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1; |
d6bbbd29 RJ |
2956 | last_page = swap_header->info.last_page; |
2957 | if (last_page > maxpages) { | |
465c47fd | 2958 | pr_warn("Truncating oversized swap area, only using %luk out of %luk\n", |
d6bbbd29 RJ |
2959 | maxpages << (PAGE_SHIFT - 10), |
2960 | last_page << (PAGE_SHIFT - 10)); | |
2961 | } | |
2962 | if (maxpages > last_page) { | |
2963 | maxpages = last_page + 1; | |
ca8bd38b CEB |
2964 | /* p->max is an unsigned int: don't overflow it */ |
2965 | if ((unsigned int)maxpages == 0) | |
2966 | maxpages = UINT_MAX; | |
2967 | } | |
2968 | p->highest_bit = maxpages - 1; | |
2969 | ||
2970 | if (!maxpages) | |
38719025 | 2971 | return 0; |
ca8bd38b CEB |
2972 | swapfilepages = i_size_read(inode) >> PAGE_SHIFT; |
2973 | if (swapfilepages && maxpages > swapfilepages) { | |
465c47fd | 2974 | pr_warn("Swap area shorter than signature indicates\n"); |
38719025 | 2975 | return 0; |
ca8bd38b CEB |
2976 | } |
2977 | if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) | |
38719025 | 2978 | return 0; |
ca8bd38b | 2979 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
38719025 | 2980 | return 0; |
ca8bd38b CEB |
2981 | |
2982 | return maxpages; | |
ca8bd38b CEB |
2983 | } |
2984 | ||
4b3ef9da | 2985 | #define SWAP_CLUSTER_INFO_COLS \ |
235b6217 | 2986 | DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info)) |
4b3ef9da HY |
2987 | #define SWAP_CLUSTER_SPACE_COLS \ |
2988 | DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER) | |
2989 | #define SWAP_CLUSTER_COLS \ | |
2990 | max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS) | |
235b6217 | 2991 | |
915d4d7b CEB |
2992 | static int setup_swap_map_and_extents(struct swap_info_struct *p, |
2993 | union swap_header *swap_header, | |
2994 | unsigned char *swap_map, | |
2a8f9449 | 2995 | struct swap_cluster_info *cluster_info, |
915d4d7b CEB |
2996 | unsigned long maxpages, |
2997 | sector_t *span) | |
2998 | { | |
235b6217 | 2999 | unsigned int j, k; |
915d4d7b CEB |
3000 | unsigned int nr_good_pages; |
3001 | int nr_extents; | |
2a8f9449 | 3002 | unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); |
235b6217 HY |
3003 | unsigned long col = p->cluster_next / SWAPFILE_CLUSTER % SWAP_CLUSTER_COLS; |
3004 | unsigned long i, idx; | |
915d4d7b CEB |
3005 | |
3006 | nr_good_pages = maxpages - 1; /* omit header page */ | |
3007 | ||
6b534915 HY |
3008 | cluster_list_init(&p->free_clusters); |
3009 | cluster_list_init(&p->discard_clusters); | |
2a8f9449 | 3010 | |
915d4d7b CEB |
3011 | for (i = 0; i < swap_header->info.nr_badpages; i++) { |
3012 | unsigned int page_nr = swap_header->info.badpages[i]; | |
bdb8e3f6 CEB |
3013 | if (page_nr == 0 || page_nr > swap_header->info.last_page) |
3014 | return -EINVAL; | |
915d4d7b CEB |
3015 | if (page_nr < maxpages) { |
3016 | swap_map[page_nr] = SWAP_MAP_BAD; | |
3017 | nr_good_pages--; | |
2a8f9449 SL |
3018 | /* |
3019 | * Haven't marked the cluster free yet, no list | |
3020 | * operation involved | |
3021 | */ | |
3022 | inc_cluster_info_page(p, cluster_info, page_nr); | |
915d4d7b CEB |
3023 | } |
3024 | } | |
3025 | ||
2a8f9449 SL |
3026 | /* Haven't marked the cluster free yet, no list operation involved */ |
3027 | for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++) | |
3028 | inc_cluster_info_page(p, cluster_info, i); | |
3029 | ||
915d4d7b CEB |
3030 | if (nr_good_pages) { |
3031 | swap_map[0] = SWAP_MAP_BAD; | |
2a8f9449 SL |
3032 | /* |
3033 | * Not mark the cluster free yet, no list | |
3034 | * operation involved | |
3035 | */ | |
3036 | inc_cluster_info_page(p, cluster_info, 0); | |
915d4d7b CEB |
3037 | p->max = maxpages; |
3038 | p->pages = nr_good_pages; | |
3039 | nr_extents = setup_swap_extents(p, span); | |
bdb8e3f6 CEB |
3040 | if (nr_extents < 0) |
3041 | return nr_extents; | |
915d4d7b CEB |
3042 | nr_good_pages = p->pages; |
3043 | } | |
3044 | if (!nr_good_pages) { | |
465c47fd | 3045 | pr_warn("Empty swap-file\n"); |
bdb8e3f6 | 3046 | return -EINVAL; |
915d4d7b CEB |
3047 | } |
3048 | ||
2a8f9449 SL |
3049 | if (!cluster_info) |
3050 | return nr_extents; | |
3051 | ||
235b6217 | 3052 | |
4b3ef9da HY |
3053 | /* |
3054 | * Reduce false cache line sharing between cluster_info and | |
3055 | * sharing same address space. | |
3056 | */ | |
235b6217 HY |
3057 | for (k = 0; k < SWAP_CLUSTER_COLS; k++) { |
3058 | j = (k + col) % SWAP_CLUSTER_COLS; | |
3059 | for (i = 0; i < DIV_ROUND_UP(nr_clusters, SWAP_CLUSTER_COLS); i++) { | |
3060 | idx = i * SWAP_CLUSTER_COLS + j; | |
3061 | if (idx >= nr_clusters) | |
3062 | continue; | |
3063 | if (cluster_count(&cluster_info[idx])) | |
3064 | continue; | |
2a8f9449 | 3065 | cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE); |
6b534915 HY |
3066 | cluster_list_add_tail(&p->free_clusters, cluster_info, |
3067 | idx); | |
2a8f9449 | 3068 | } |
2a8f9449 | 3069 | } |
915d4d7b | 3070 | return nr_extents; |
915d4d7b CEB |
3071 | } |
3072 | ||
dcf6b7dd RA |
3073 | /* |
3074 | * Helper to sys_swapon determining if a given swap | |
3075 | * backing device queue supports DISCARD operations. | |
3076 | */ | |
3077 | static bool swap_discardable(struct swap_info_struct *si) | |
3078 | { | |
3079 | struct request_queue *q = bdev_get_queue(si->bdev); | |
3080 | ||
3081 | if (!q || !blk_queue_discard(q)) | |
3082 | return false; | |
3083 | ||
3084 | return true; | |
3085 | } | |
3086 | ||
53cbb243 CEB |
3087 | SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) |
3088 | { | |
3089 | struct swap_info_struct *p; | |
91a27b2a | 3090 | struct filename *name; |
53cbb243 CEB |
3091 | struct file *swap_file = NULL; |
3092 | struct address_space *mapping; | |
40531542 | 3093 | int prio; |
53cbb243 CEB |
3094 | int error; |
3095 | union swap_header *swap_header; | |
915d4d7b | 3096 | int nr_extents; |
53cbb243 CEB |
3097 | sector_t span; |
3098 | unsigned long maxpages; | |
53cbb243 | 3099 | unsigned char *swap_map = NULL; |
2a8f9449 | 3100 | struct swap_cluster_info *cluster_info = NULL; |
38b5faf4 | 3101 | unsigned long *frontswap_map = NULL; |
53cbb243 CEB |
3102 | struct page *page = NULL; |
3103 | struct inode *inode = NULL; | |
53cbb243 | 3104 | |
d15cab97 HD |
3105 | if (swap_flags & ~SWAP_FLAGS_VALID) |
3106 | return -EINVAL; | |
3107 | ||
53cbb243 CEB |
3108 | if (!capable(CAP_SYS_ADMIN)) |
3109 | return -EPERM; | |
3110 | ||
a2468cc9 AL |
3111 | if (!swap_avail_heads) |
3112 | return -ENOMEM; | |
3113 | ||
53cbb243 | 3114 | p = alloc_swap_info(); |
2542e513 CEB |
3115 | if (IS_ERR(p)) |
3116 | return PTR_ERR(p); | |
53cbb243 | 3117 | |
815c2c54 SL |
3118 | INIT_WORK(&p->discard_work, swap_discard_work); |
3119 | ||
1da177e4 | 3120 | name = getname(specialfile); |
1da177e4 | 3121 | if (IS_ERR(name)) { |
7de7fb6b | 3122 | error = PTR_ERR(name); |
1da177e4 | 3123 | name = NULL; |
bd69010b | 3124 | goto bad_swap; |
1da177e4 | 3125 | } |
669abf4e | 3126 | swap_file = file_open_name(name, O_RDWR|O_LARGEFILE, 0); |
1da177e4 | 3127 | if (IS_ERR(swap_file)) { |
7de7fb6b | 3128 | error = PTR_ERR(swap_file); |
1da177e4 | 3129 | swap_file = NULL; |
bd69010b | 3130 | goto bad_swap; |
1da177e4 LT |
3131 | } |
3132 | ||
3133 | p->swap_file = swap_file; | |
3134 | mapping = swap_file->f_mapping; | |
2130781e | 3135 | inode = mapping->host; |
6f179af8 | 3136 | |
5955102c | 3137 | /* If S_ISREG(inode->i_mode) will do inode_lock(inode); */ |
4d0e1e10 CEB |
3138 | error = claim_swapfile(p, inode); |
3139 | if (unlikely(error)) | |
1da177e4 | 3140 | goto bad_swap; |
1da177e4 | 3141 | |
1da177e4 LT |
3142 | /* |
3143 | * Read the swap header. | |
3144 | */ | |
3145 | if (!mapping->a_ops->readpage) { | |
3146 | error = -EINVAL; | |
3147 | goto bad_swap; | |
3148 | } | |
090d2b18 | 3149 | page = read_mapping_page(mapping, 0, swap_file); |
1da177e4 LT |
3150 | if (IS_ERR(page)) { |
3151 | error = PTR_ERR(page); | |
3152 | goto bad_swap; | |
3153 | } | |
81e33971 | 3154 | swap_header = kmap(page); |
1da177e4 | 3155 | |
ca8bd38b CEB |
3156 | maxpages = read_swap_header(p, swap_header, inode); |
3157 | if (unlikely(!maxpages)) { | |
1da177e4 LT |
3158 | error = -EINVAL; |
3159 | goto bad_swap; | |
3160 | } | |
886bb7e9 | 3161 | |
81e33971 | 3162 | /* OK, set up the swap map and apply the bad block list */ |
803d0c83 | 3163 | swap_map = vzalloc(maxpages); |
81e33971 HD |
3164 | if (!swap_map) { |
3165 | error = -ENOMEM; | |
3166 | goto bad_swap; | |
3167 | } | |
f0571429 MK |
3168 | |
3169 | if (bdi_cap_stable_pages_required(inode_to_bdi(inode))) | |
3170 | p->flags |= SWP_STABLE_WRITES; | |
3171 | ||
2a8f9449 | 3172 | if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) { |
6f179af8 | 3173 | int cpu; |
235b6217 | 3174 | unsigned long ci, nr_cluster; |
6f179af8 | 3175 | |
2a8f9449 SL |
3176 | p->flags |= SWP_SOLIDSTATE; |
3177 | /* | |
3178 | * select a random position to start with to help wear leveling | |
3179 | * SSD | |
3180 | */ | |
3181 | p->cluster_next = 1 + (prandom_u32() % p->highest_bit); | |
235b6217 | 3182 | nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); |
2a8f9449 | 3183 | |
54f180d3 HY |
3184 | cluster_info = kvzalloc(nr_cluster * sizeof(*cluster_info), |
3185 | GFP_KERNEL); | |
2a8f9449 SL |
3186 | if (!cluster_info) { |
3187 | error = -ENOMEM; | |
3188 | goto bad_swap; | |
3189 | } | |
235b6217 HY |
3190 | |
3191 | for (ci = 0; ci < nr_cluster; ci++) | |
3192 | spin_lock_init(&((cluster_info + ci)->lock)); | |
3193 | ||
ebc2a1a6 SL |
3194 | p->percpu_cluster = alloc_percpu(struct percpu_cluster); |
3195 | if (!p->percpu_cluster) { | |
3196 | error = -ENOMEM; | |
3197 | goto bad_swap; | |
3198 | } | |
6f179af8 | 3199 | for_each_possible_cpu(cpu) { |
ebc2a1a6 | 3200 | struct percpu_cluster *cluster; |
6f179af8 | 3201 | cluster = per_cpu_ptr(p->percpu_cluster, cpu); |
ebc2a1a6 SL |
3202 | cluster_set_null(&cluster->index); |
3203 | } | |
81a0298b HY |
3204 | } else |
3205 | atomic_inc(&nr_rotate_swap); | |
1da177e4 | 3206 | |
1421ef3c CEB |
3207 | error = swap_cgroup_swapon(p->type, maxpages); |
3208 | if (error) | |
3209 | goto bad_swap; | |
3210 | ||
915d4d7b | 3211 | nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map, |
2a8f9449 | 3212 | cluster_info, maxpages, &span); |
915d4d7b CEB |
3213 | if (unlikely(nr_extents < 0)) { |
3214 | error = nr_extents; | |
1da177e4 LT |
3215 | goto bad_swap; |
3216 | } | |
38b5faf4 | 3217 | /* frontswap enabled? set up bit-per-page map for frontswap */ |
8ea1d2a1 | 3218 | if (IS_ENABLED(CONFIG_FRONTSWAP)) |
54f180d3 HY |
3219 | frontswap_map = kvzalloc(BITS_TO_LONGS(maxpages) * sizeof(long), |
3220 | GFP_KERNEL); | |
1da177e4 | 3221 | |
2a8f9449 SL |
3222 | if (p->bdev &&(swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) { |
3223 | /* | |
3224 | * When discard is enabled for swap with no particular | |
3225 | * policy flagged, we set all swap discard flags here in | |
3226 | * order to sustain backward compatibility with older | |
3227 | * swapon(8) releases. | |
3228 | */ | |
3229 | p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD | | |
3230 | SWP_PAGE_DISCARD); | |
dcf6b7dd | 3231 | |
2a8f9449 SL |
3232 | /* |
3233 | * By flagging sys_swapon, a sysadmin can tell us to | |
3234 | * either do single-time area discards only, or to just | |
3235 | * perform discards for released swap page-clusters. | |
3236 | * Now it's time to adjust the p->flags accordingly. | |
3237 | */ | |
3238 | if (swap_flags & SWAP_FLAG_DISCARD_ONCE) | |
3239 | p->flags &= ~SWP_PAGE_DISCARD; | |
3240 | else if (swap_flags & SWAP_FLAG_DISCARD_PAGES) | |
3241 | p->flags &= ~SWP_AREA_DISCARD; | |
3242 | ||
3243 | /* issue a swapon-time discard if it's still required */ | |
3244 | if (p->flags & SWP_AREA_DISCARD) { | |
3245 | int err = discard_swap(p); | |
3246 | if (unlikely(err)) | |
3247 | pr_err("swapon: discard_swap(%p): %d\n", | |
3248 | p, err); | |
dcf6b7dd | 3249 | } |
20137a49 | 3250 | } |
6a6ba831 | 3251 | |
4b3ef9da HY |
3252 | error = init_swap_address_space(p->type, maxpages); |
3253 | if (error) | |
3254 | goto bad_swap; | |
3255 | ||
fc0abb14 | 3256 | mutex_lock(&swapon_mutex); |
40531542 | 3257 | prio = -1; |
78ecba08 | 3258 | if (swap_flags & SWAP_FLAG_PREFER) |
40531542 | 3259 | prio = |
78ecba08 | 3260 | (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; |
2a8f9449 | 3261 | enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map); |
c69dbfb8 | 3262 | |
756a025f | 3263 | pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n", |
91a27b2a | 3264 | p->pages<<(PAGE_SHIFT-10), name->name, p->prio, |
c69dbfb8 CEB |
3265 | nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), |
3266 | (p->flags & SWP_SOLIDSTATE) ? "SS" : "", | |
38b5faf4 | 3267 | (p->flags & SWP_DISCARDABLE) ? "D" : "", |
dcf6b7dd RA |
3268 | (p->flags & SWP_AREA_DISCARD) ? "s" : "", |
3269 | (p->flags & SWP_PAGE_DISCARD) ? "c" : "", | |
38b5faf4 | 3270 | (frontswap_map) ? "FS" : ""); |
c69dbfb8 | 3271 | |
fc0abb14 | 3272 | mutex_unlock(&swapon_mutex); |
66d7dd51 KS |
3273 | atomic_inc(&proc_poll_event); |
3274 | wake_up_interruptible(&proc_poll_wait); | |
3275 | ||
9b01c350 CEB |
3276 | if (S_ISREG(inode->i_mode)) |
3277 | inode->i_flags |= S_SWAPFILE; | |
1da177e4 LT |
3278 | error = 0; |
3279 | goto out; | |
3280 | bad_swap: | |
ebc2a1a6 SL |
3281 | free_percpu(p->percpu_cluster); |
3282 | p->percpu_cluster = NULL; | |
bd69010b | 3283 | if (inode && S_ISBLK(inode->i_mode) && p->bdev) { |
f2090d2d CEB |
3284 | set_blocksize(p->bdev, p->old_block_size); |
3285 | blkdev_put(p->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); | |
1da177e4 | 3286 | } |
4cd3bb10 | 3287 | destroy_swap_extents(p); |
e8e6c2ec | 3288 | swap_cgroup_swapoff(p->type); |
5d337b91 | 3289 | spin_lock(&swap_lock); |
1da177e4 | 3290 | p->swap_file = NULL; |
1da177e4 | 3291 | p->flags = 0; |
5d337b91 | 3292 | spin_unlock(&swap_lock); |
1da177e4 | 3293 | vfree(swap_map); |
8606a1a9 | 3294 | kvfree(cluster_info); |
b6b1fd2a | 3295 | kvfree(frontswap_map); |
52c50567 | 3296 | if (swap_file) { |
2130781e | 3297 | if (inode && S_ISREG(inode->i_mode)) { |
5955102c | 3298 | inode_unlock(inode); |
2130781e CEB |
3299 | inode = NULL; |
3300 | } | |
1da177e4 | 3301 | filp_close(swap_file, NULL); |
52c50567 | 3302 | } |
1da177e4 LT |
3303 | out: |
3304 | if (page && !IS_ERR(page)) { | |
3305 | kunmap(page); | |
09cbfeaf | 3306 | put_page(page); |
1da177e4 LT |
3307 | } |
3308 | if (name) | |
3309 | putname(name); | |
9b01c350 | 3310 | if (inode && S_ISREG(inode->i_mode)) |
5955102c | 3311 | inode_unlock(inode); |
039939a6 TC |
3312 | if (!error) |
3313 | enable_swap_slots_cache(); | |
1da177e4 LT |
3314 | return error; |
3315 | } | |
3316 | ||
3317 | void si_swapinfo(struct sysinfo *val) | |
3318 | { | |
efa90a98 | 3319 | unsigned int type; |
1da177e4 LT |
3320 | unsigned long nr_to_be_unused = 0; |
3321 | ||
5d337b91 | 3322 | spin_lock(&swap_lock); |
efa90a98 HD |
3323 | for (type = 0; type < nr_swapfiles; type++) { |
3324 | struct swap_info_struct *si = swap_info[type]; | |
3325 | ||
3326 | if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK)) | |
3327 | nr_to_be_unused += si->inuse_pages; | |
1da177e4 | 3328 | } |
ec8acf20 | 3329 | val->freeswap = atomic_long_read(&nr_swap_pages) + nr_to_be_unused; |
1da177e4 | 3330 | val->totalswap = total_swap_pages + nr_to_be_unused; |
5d337b91 | 3331 | spin_unlock(&swap_lock); |
1da177e4 LT |
3332 | } |
3333 | ||
3334 | /* | |
3335 | * Verify that a swap entry is valid and increment its swap map count. | |
3336 | * | |
355cfa73 KH |
3337 | * Returns error code in following case. |
3338 | * - success -> 0 | |
3339 | * - swp_entry is invalid -> EINVAL | |
3340 | * - swp_entry is migration entry -> EINVAL | |
3341 | * - swap-cache reference is requested but there is already one. -> EEXIST | |
3342 | * - swap-cache reference is requested but the entry is not used. -> ENOENT | |
570a335b | 3343 | * - swap-mapped reference requested but needs continued swap count. -> ENOMEM |
1da177e4 | 3344 | */ |
8d69aaee | 3345 | static int __swap_duplicate(swp_entry_t entry, unsigned char usage) |
1da177e4 | 3346 | { |
73c34b6a | 3347 | struct swap_info_struct *p; |
235b6217 | 3348 | struct swap_cluster_info *ci; |
1da177e4 | 3349 | unsigned long offset, type; |
8d69aaee HD |
3350 | unsigned char count; |
3351 | unsigned char has_cache; | |
253d553b | 3352 | int err = -EINVAL; |
1da177e4 | 3353 | |
a7420aa5 | 3354 | if (non_swap_entry(entry)) |
253d553b | 3355 | goto out; |
0697212a | 3356 | |
1da177e4 LT |
3357 | type = swp_type(entry); |
3358 | if (type >= nr_swapfiles) | |
3359 | goto bad_file; | |
efa90a98 | 3360 | p = swap_info[type]; |
1da177e4 | 3361 | offset = swp_offset(entry); |
355cfa73 | 3362 | if (unlikely(offset >= p->max)) |
235b6217 HY |
3363 | goto out; |
3364 | ||
3365 | ci = lock_cluster_or_swap_info(p, offset); | |
355cfa73 | 3366 | |
253d553b | 3367 | count = p->swap_map[offset]; |
edfe23da SL |
3368 | |
3369 | /* | |
3370 | * swapin_readahead() doesn't check if a swap entry is valid, so the | |
3371 | * swap entry could be SWAP_MAP_BAD. Check here with lock held. | |
3372 | */ | |
3373 | if (unlikely(swap_count(count) == SWAP_MAP_BAD)) { | |
3374 | err = -ENOENT; | |
3375 | goto unlock_out; | |
3376 | } | |
3377 | ||
253d553b HD |
3378 | has_cache = count & SWAP_HAS_CACHE; |
3379 | count &= ~SWAP_HAS_CACHE; | |
3380 | err = 0; | |
355cfa73 | 3381 | |
253d553b | 3382 | if (usage == SWAP_HAS_CACHE) { |
355cfa73 KH |
3383 | |
3384 | /* set SWAP_HAS_CACHE if there is no cache and entry is used */ | |
253d553b HD |
3385 | if (!has_cache && count) |
3386 | has_cache = SWAP_HAS_CACHE; | |
3387 | else if (has_cache) /* someone else added cache */ | |
3388 | err = -EEXIST; | |
3389 | else /* no users remaining */ | |
3390 | err = -ENOENT; | |
355cfa73 KH |
3391 | |
3392 | } else if (count || has_cache) { | |
253d553b | 3393 | |
570a335b HD |
3394 | if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX) |
3395 | count += usage; | |
3396 | else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) | |
253d553b | 3397 | err = -EINVAL; |
570a335b HD |
3398 | else if (swap_count_continued(p, offset, count)) |
3399 | count = COUNT_CONTINUED; | |
3400 | else | |
3401 | err = -ENOMEM; | |
355cfa73 | 3402 | } else |
253d553b HD |
3403 | err = -ENOENT; /* unused swap entry */ |
3404 | ||
3405 | p->swap_map[offset] = count | has_cache; | |
3406 | ||
355cfa73 | 3407 | unlock_out: |
235b6217 | 3408 | unlock_cluster_or_swap_info(p, ci); |
1da177e4 | 3409 | out: |
253d553b | 3410 | return err; |
1da177e4 LT |
3411 | |
3412 | bad_file: | |
465c47fd | 3413 | pr_err("swap_dup: %s%08lx\n", Bad_file, entry.val); |
1da177e4 LT |
3414 | goto out; |
3415 | } | |
253d553b | 3416 | |
aaa46865 HD |
3417 | /* |
3418 | * Help swapoff by noting that swap entry belongs to shmem/tmpfs | |
3419 | * (in which case its reference count is never incremented). | |
3420 | */ | |
3421 | void swap_shmem_alloc(swp_entry_t entry) | |
3422 | { | |
3423 | __swap_duplicate(entry, SWAP_MAP_SHMEM); | |
3424 | } | |
3425 | ||
355cfa73 | 3426 | /* |
08259d58 HD |
3427 | * Increase reference count of swap entry by 1. |
3428 | * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required | |
3429 | * but could not be atomically allocated. Returns 0, just as if it succeeded, | |
3430 | * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which | |
3431 | * might occur if a page table entry has got corrupted. | |
355cfa73 | 3432 | */ |
570a335b | 3433 | int swap_duplicate(swp_entry_t entry) |
355cfa73 | 3434 | { |
570a335b HD |
3435 | int err = 0; |
3436 | ||
3437 | while (!err && __swap_duplicate(entry, 1) == -ENOMEM) | |
3438 | err = add_swap_count_continuation(entry, GFP_ATOMIC); | |
3439 | return err; | |
355cfa73 | 3440 | } |
1da177e4 | 3441 | |
cb4b86ba | 3442 | /* |
355cfa73 KH |
3443 | * @entry: swap entry for which we allocate swap cache. |
3444 | * | |
73c34b6a | 3445 | * Called when allocating swap cache for existing swap entry, |
355cfa73 KH |
3446 | * This can return error codes. Returns 0 at success. |
3447 | * -EBUSY means there is a swap cache. | |
3448 | * Note: return code is different from swap_duplicate(). | |
cb4b86ba KH |
3449 | */ |
3450 | int swapcache_prepare(swp_entry_t entry) | |
3451 | { | |
253d553b | 3452 | return __swap_duplicate(entry, SWAP_HAS_CACHE); |
cb4b86ba KH |
3453 | } |
3454 | ||
f981c595 MG |
3455 | struct swap_info_struct *page_swap_info(struct page *page) |
3456 | { | |
3457 | swp_entry_t swap = { .val = page_private(page) }; | |
f981c595 MG |
3458 | return swap_info[swp_type(swap)]; |
3459 | } | |
3460 | ||
3461 | /* | |
3462 | * out-of-line __page_file_ methods to avoid include hell. | |
3463 | */ | |
3464 | struct address_space *__page_file_mapping(struct page *page) | |
3465 | { | |
309381fe | 3466 | VM_BUG_ON_PAGE(!PageSwapCache(page), page); |
f981c595 MG |
3467 | return page_swap_info(page)->swap_file->f_mapping; |
3468 | } | |
3469 | EXPORT_SYMBOL_GPL(__page_file_mapping); | |
3470 | ||
3471 | pgoff_t __page_file_index(struct page *page) | |
3472 | { | |
3473 | swp_entry_t swap = { .val = page_private(page) }; | |
309381fe | 3474 | VM_BUG_ON_PAGE(!PageSwapCache(page), page); |
f981c595 MG |
3475 | return swp_offset(swap); |
3476 | } | |
3477 | EXPORT_SYMBOL_GPL(__page_file_index); | |
3478 | ||
570a335b HD |
3479 | /* |
3480 | * add_swap_count_continuation - called when a swap count is duplicated | |
3481 | * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's | |
3482 | * page of the original vmalloc'ed swap_map, to hold the continuation count | |
3483 | * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called | |
3484 | * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc. | |
3485 | * | |
3486 | * These continuation pages are seldom referenced: the common paths all work | |
3487 | * on the original swap_map, only referring to a continuation page when the | |
3488 | * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX. | |
3489 | * | |
3490 | * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding | |
3491 | * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL) | |
3492 | * can be called after dropping locks. | |
3493 | */ | |
3494 | int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask) | |
3495 | { | |
3496 | struct swap_info_struct *si; | |
235b6217 | 3497 | struct swap_cluster_info *ci; |
570a335b HD |
3498 | struct page *head; |
3499 | struct page *page; | |
3500 | struct page *list_page; | |
3501 | pgoff_t offset; | |
3502 | unsigned char count; | |
3503 | ||
3504 | /* | |
3505 | * When debugging, it's easier to use __GFP_ZERO here; but it's better | |
3506 | * for latency not to zero a page while GFP_ATOMIC and holding locks. | |
3507 | */ | |
3508 | page = alloc_page(gfp_mask | __GFP_HIGHMEM); | |
3509 | ||
3510 | si = swap_info_get(entry); | |
3511 | if (!si) { | |
3512 | /* | |
3513 | * An acceptable race has occurred since the failing | |
3514 | * __swap_duplicate(): the swap entry has been freed, | |
3515 | * perhaps even the whole swap_map cleared for swapoff. | |
3516 | */ | |
3517 | goto outer; | |
3518 | } | |
3519 | ||
3520 | offset = swp_offset(entry); | |
235b6217 HY |
3521 | |
3522 | ci = lock_cluster(si, offset); | |
3523 | ||
570a335b HD |
3524 | count = si->swap_map[offset] & ~SWAP_HAS_CACHE; |
3525 | ||
3526 | if ((count & ~COUNT_CONTINUED) != SWAP_MAP_MAX) { | |
3527 | /* | |
3528 | * The higher the swap count, the more likely it is that tasks | |
3529 | * will race to add swap count continuation: we need to avoid | |
3530 | * over-provisioning. | |
3531 | */ | |
3532 | goto out; | |
3533 | } | |
3534 | ||
3535 | if (!page) { | |
235b6217 | 3536 | unlock_cluster(ci); |
ec8acf20 | 3537 | spin_unlock(&si->lock); |
570a335b HD |
3538 | return -ENOMEM; |
3539 | } | |
3540 | ||
3541 | /* | |
3542 | * We are fortunate that although vmalloc_to_page uses pte_offset_map, | |
2de1a7e4 SJ |
3543 | * no architecture is using highmem pages for kernel page tables: so it |
3544 | * will not corrupt the GFP_ATOMIC caller's atomic page table kmaps. | |
570a335b HD |
3545 | */ |
3546 | head = vmalloc_to_page(si->swap_map + offset); | |
3547 | offset &= ~PAGE_MASK; | |
3548 | ||
2628bd6f | 3549 | spin_lock(&si->cont_lock); |
570a335b HD |
3550 | /* |
3551 | * Page allocation does not initialize the page's lru field, | |
3552 | * but it does always reset its private field. | |
3553 | */ | |
3554 | if (!page_private(head)) { | |
3555 | BUG_ON(count & COUNT_CONTINUED); | |
3556 | INIT_LIST_HEAD(&head->lru); | |
3557 | set_page_private(head, SWP_CONTINUED); | |
3558 | si->flags |= SWP_CONTINUED; | |
3559 | } | |
3560 | ||
3561 | list_for_each_entry(list_page, &head->lru, lru) { | |
3562 | unsigned char *map; | |
3563 | ||
3564 | /* | |
3565 | * If the previous map said no continuation, but we've found | |
3566 | * a continuation page, free our allocation and use this one. | |
3567 | */ | |
3568 | if (!(count & COUNT_CONTINUED)) | |
2628bd6f | 3569 | goto out_unlock_cont; |
570a335b | 3570 | |
9b04c5fe | 3571 | map = kmap_atomic(list_page) + offset; |
570a335b | 3572 | count = *map; |
9b04c5fe | 3573 | kunmap_atomic(map); |
570a335b HD |
3574 | |
3575 | /* | |
3576 | * If this continuation count now has some space in it, | |
3577 | * free our allocation and use this one. | |
3578 | */ | |
3579 | if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX) | |
2628bd6f | 3580 | goto out_unlock_cont; |
570a335b HD |
3581 | } |
3582 | ||
3583 | list_add_tail(&page->lru, &head->lru); | |
3584 | page = NULL; /* now it's attached, don't free it */ | |
2628bd6f HY |
3585 | out_unlock_cont: |
3586 | spin_unlock(&si->cont_lock); | |
570a335b | 3587 | out: |
235b6217 | 3588 | unlock_cluster(ci); |
ec8acf20 | 3589 | spin_unlock(&si->lock); |
570a335b HD |
3590 | outer: |
3591 | if (page) | |
3592 | __free_page(page); | |
3593 | return 0; | |
3594 | } | |
3595 | ||
3596 | /* | |
3597 | * swap_count_continued - when the original swap_map count is incremented | |
3598 | * from SWAP_MAP_MAX, check if there is already a continuation page to carry | |
3599 | * into, carry if so, or else fail until a new continuation page is allocated; | |
3600 | * when the original swap_map count is decremented from 0 with continuation, | |
3601 | * borrow from the continuation and report whether it still holds more. | |
235b6217 HY |
3602 | * Called while __swap_duplicate() or swap_entry_free() holds swap or cluster |
3603 | * lock. | |
570a335b HD |
3604 | */ |
3605 | static bool swap_count_continued(struct swap_info_struct *si, | |
3606 | pgoff_t offset, unsigned char count) | |
3607 | { | |
3608 | struct page *head; | |
3609 | struct page *page; | |
3610 | unsigned char *map; | |
2628bd6f | 3611 | bool ret; |
570a335b HD |
3612 | |
3613 | head = vmalloc_to_page(si->swap_map + offset); | |
3614 | if (page_private(head) != SWP_CONTINUED) { | |
3615 | BUG_ON(count & COUNT_CONTINUED); | |
3616 | return false; /* need to add count continuation */ | |
3617 | } | |
3618 | ||
2628bd6f | 3619 | spin_lock(&si->cont_lock); |
570a335b HD |
3620 | offset &= ~PAGE_MASK; |
3621 | page = list_entry(head->lru.next, struct page, lru); | |
9b04c5fe | 3622 | map = kmap_atomic(page) + offset; |
570a335b HD |
3623 | |
3624 | if (count == SWAP_MAP_MAX) /* initial increment from swap_map */ | |
3625 | goto init_map; /* jump over SWAP_CONT_MAX checks */ | |
3626 | ||
3627 | if (count == (SWAP_MAP_MAX | COUNT_CONTINUED)) { /* incrementing */ | |
3628 | /* | |
3629 | * Think of how you add 1 to 999 | |
3630 | */ | |
3631 | while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) { | |
9b04c5fe | 3632 | kunmap_atomic(map); |
570a335b HD |
3633 | page = list_entry(page->lru.next, struct page, lru); |
3634 | BUG_ON(page == head); | |
9b04c5fe | 3635 | map = kmap_atomic(page) + offset; |
570a335b HD |
3636 | } |
3637 | if (*map == SWAP_CONT_MAX) { | |
9b04c5fe | 3638 | kunmap_atomic(map); |
570a335b | 3639 | page = list_entry(page->lru.next, struct page, lru); |
2628bd6f HY |
3640 | if (page == head) { |
3641 | ret = false; /* add count continuation */ | |
3642 | goto out; | |
3643 | } | |
9b04c5fe | 3644 | map = kmap_atomic(page) + offset; |
570a335b HD |
3645 | init_map: *map = 0; /* we didn't zero the page */ |
3646 | } | |
3647 | *map += 1; | |
9b04c5fe | 3648 | kunmap_atomic(map); |
570a335b HD |
3649 | page = list_entry(page->lru.prev, struct page, lru); |
3650 | while (page != head) { | |
9b04c5fe | 3651 | map = kmap_atomic(page) + offset; |
570a335b | 3652 | *map = COUNT_CONTINUED; |
9b04c5fe | 3653 | kunmap_atomic(map); |
570a335b HD |
3654 | page = list_entry(page->lru.prev, struct page, lru); |
3655 | } | |
2628bd6f | 3656 | ret = true; /* incremented */ |
570a335b HD |
3657 | |
3658 | } else { /* decrementing */ | |
3659 | /* | |
3660 | * Think of how you subtract 1 from 1000 | |
3661 | */ | |
3662 | BUG_ON(count != COUNT_CONTINUED); | |
3663 | while (*map == COUNT_CONTINUED) { | |
9b04c5fe | 3664 | kunmap_atomic(map); |
570a335b HD |
3665 | page = list_entry(page->lru.next, struct page, lru); |
3666 | BUG_ON(page == head); | |
9b04c5fe | 3667 | map = kmap_atomic(page) + offset; |
570a335b HD |
3668 | } |
3669 | BUG_ON(*map == 0); | |
3670 | *map -= 1; | |
3671 | if (*map == 0) | |
3672 | count = 0; | |
9b04c5fe | 3673 | kunmap_atomic(map); |
570a335b HD |
3674 | page = list_entry(page->lru.prev, struct page, lru); |
3675 | while (page != head) { | |
9b04c5fe | 3676 | map = kmap_atomic(page) + offset; |
570a335b HD |
3677 | *map = SWAP_CONT_MAX | count; |
3678 | count = COUNT_CONTINUED; | |
9b04c5fe | 3679 | kunmap_atomic(map); |
570a335b HD |
3680 | page = list_entry(page->lru.prev, struct page, lru); |
3681 | } | |
2628bd6f | 3682 | ret = count == COUNT_CONTINUED; |
570a335b | 3683 | } |
2628bd6f HY |
3684 | out: |
3685 | spin_unlock(&si->cont_lock); | |
3686 | return ret; | |
570a335b HD |
3687 | } |
3688 | ||
3689 | /* | |
3690 | * free_swap_count_continuations - swapoff free all the continuation pages | |
3691 | * appended to the swap_map, after swap_map is quiesced, before vfree'ing it. | |
3692 | */ | |
3693 | static void free_swap_count_continuations(struct swap_info_struct *si) | |
3694 | { | |
3695 | pgoff_t offset; | |
3696 | ||
3697 | for (offset = 0; offset < si->max; offset += PAGE_SIZE) { | |
3698 | struct page *head; | |
3699 | head = vmalloc_to_page(si->swap_map + offset); | |
3700 | if (page_private(head)) { | |
0d576d20 GT |
3701 | struct page *page, *next; |
3702 | ||
3703 | list_for_each_entry_safe(page, next, &head->lru, lru) { | |
3704 | list_del(&page->lru); | |
570a335b HD |
3705 | __free_page(page); |
3706 | } | |
3707 | } | |
3708 | } | |
3709 | } | |
a2468cc9 AL |
3710 | |
3711 | static int __init swapfile_init(void) | |
3712 | { | |
3713 | int nid; | |
3714 | ||
3715 | swap_avail_heads = kmalloc_array(nr_node_ids, sizeof(struct plist_head), | |
3716 | GFP_KERNEL); | |
3717 | if (!swap_avail_heads) { | |
3718 | pr_emerg("Not enough memory for swap heads, swap is disabled\n"); | |
3719 | return -ENOMEM; | |
3720 | } | |
3721 | ||
3722 | for_each_node(nid) | |
3723 | plist_head_init(&swap_avail_heads[nid]); | |
3724 | ||
3725 | return 0; | |
3726 | } | |
3727 | subsys_initcall(swapfile_init); |