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Commit | Line | Data |
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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 LT |
8 | #include <linux/mm.h> |
9 | #include <linux/hugetlb.h> | |
10 | #include <linux/mman.h> | |
11 | #include <linux/slab.h> | |
12 | #include <linux/kernel_stat.h> | |
13 | #include <linux/swap.h> | |
14 | #include <linux/vmalloc.h> | |
15 | #include <linux/pagemap.h> | |
16 | #include <linux/namei.h> | |
072441e2 | 17 | #include <linux/shmem_fs.h> |
1da177e4 | 18 | #include <linux/blkdev.h> |
20137a49 | 19 | #include <linux/random.h> |
1da177e4 LT |
20 | #include <linux/writeback.h> |
21 | #include <linux/proc_fs.h> | |
22 | #include <linux/seq_file.h> | |
23 | #include <linux/init.h> | |
5ad64688 | 24 | #include <linux/ksm.h> |
1da177e4 LT |
25 | #include <linux/rmap.h> |
26 | #include <linux/security.h> | |
27 | #include <linux/backing-dev.h> | |
fc0abb14 | 28 | #include <linux/mutex.h> |
c59ede7b | 29 | #include <linux/capability.h> |
1da177e4 | 30 | #include <linux/syscalls.h> |
8a9f3ccd | 31 | #include <linux/memcontrol.h> |
66d7dd51 | 32 | #include <linux/poll.h> |
72788c38 | 33 | #include <linux/oom.h> |
38b5faf4 DM |
34 | #include <linux/frontswap.h> |
35 | #include <linux/swapfile.h> | |
f981c595 | 36 | #include <linux/export.h> |
1da177e4 LT |
37 | |
38 | #include <asm/pgtable.h> | |
39 | #include <asm/tlbflush.h> | |
40 | #include <linux/swapops.h> | |
5d1ea48b | 41 | #include <linux/swap_cgroup.h> |
1da177e4 | 42 | |
570a335b HD |
43 | static bool swap_count_continued(struct swap_info_struct *, pgoff_t, |
44 | unsigned char); | |
45 | static void free_swap_count_continuations(struct swap_info_struct *); | |
d4906e1a | 46 | static sector_t map_swap_entry(swp_entry_t, struct block_device**); |
570a335b | 47 | |
38b5faf4 | 48 | DEFINE_SPINLOCK(swap_lock); |
7c363b8c | 49 | static unsigned int nr_swapfiles; |
ec8acf20 | 50 | atomic_long_t nr_swap_pages; |
fb0fec50 CW |
51 | /* |
52 | * Some modules use swappable objects and may try to swap them out under | |
53 | * memory pressure (via the shrinker). Before doing so, they may wish to | |
54 | * check to see if any swap space is available. | |
55 | */ | |
56 | EXPORT_SYMBOL_GPL(nr_swap_pages); | |
ec8acf20 | 57 | /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */ |
1da177e4 | 58 | long total_swap_pages; |
78ecba08 | 59 | static int least_priority; |
1da177e4 | 60 | |
1da177e4 LT |
61 | static const char Bad_file[] = "Bad swap file entry "; |
62 | static const char Unused_file[] = "Unused swap file entry "; | |
63 | static const char Bad_offset[] = "Bad swap offset entry "; | |
64 | static const char Unused_offset[] = "Unused swap offset entry "; | |
65 | ||
adfab836 DS |
66 | /* |
67 | * all active swap_info_structs | |
68 | * protected with swap_lock, and ordered by priority. | |
69 | */ | |
18ab4d4c DS |
70 | PLIST_HEAD(swap_active_head); |
71 | ||
72 | /* | |
73 | * all available (active, not full) swap_info_structs | |
74 | * protected with swap_avail_lock, ordered by priority. | |
75 | * This is used by get_swap_page() instead of swap_active_head | |
76 | * because swap_active_head includes all swap_info_structs, | |
77 | * but get_swap_page() doesn't need to look at full ones. | |
78 | * This uses its own lock instead of swap_lock because when a | |
79 | * swap_info_struct changes between not-full/full, it needs to | |
80 | * add/remove itself to/from this list, but the swap_info_struct->lock | |
81 | * is held and the locking order requires swap_lock to be taken | |
82 | * before any swap_info_struct->lock. | |
83 | */ | |
84 | static PLIST_HEAD(swap_avail_head); | |
85 | static DEFINE_SPINLOCK(swap_avail_lock); | |
1da177e4 | 86 | |
38b5faf4 | 87 | struct swap_info_struct *swap_info[MAX_SWAPFILES]; |
1da177e4 | 88 | |
fc0abb14 | 89 | static DEFINE_MUTEX(swapon_mutex); |
1da177e4 | 90 | |
66d7dd51 KS |
91 | static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait); |
92 | /* Activity counter to indicate that a swapon or swapoff has occurred */ | |
93 | static atomic_t proc_poll_event = ATOMIC_INIT(0); | |
94 | ||
8d69aaee | 95 | static inline unsigned char swap_count(unsigned char ent) |
355cfa73 | 96 | { |
570a335b | 97 | return ent & ~SWAP_HAS_CACHE; /* may include SWAP_HAS_CONT flag */ |
355cfa73 KH |
98 | } |
99 | ||
efa90a98 | 100 | /* returns 1 if swap entry is freed */ |
c9e44410 KH |
101 | static int |
102 | __try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset) | |
103 | { | |
efa90a98 | 104 | swp_entry_t entry = swp_entry(si->type, offset); |
c9e44410 KH |
105 | struct page *page; |
106 | int ret = 0; | |
107 | ||
f6ab1f7f | 108 | page = find_get_page(swap_address_space(entry), swp_offset(entry)); |
c9e44410 KH |
109 | if (!page) |
110 | return 0; | |
111 | /* | |
112 | * This function is called from scan_swap_map() and it's called | |
113 | * by vmscan.c at reclaiming pages. So, we hold a lock on a page, here. | |
114 | * We have to use trylock for avoiding deadlock. This is a special | |
115 | * case and you should use try_to_free_swap() with explicit lock_page() | |
116 | * in usual operations. | |
117 | */ | |
118 | if (trylock_page(page)) { | |
119 | ret = try_to_free_swap(page); | |
120 | unlock_page(page); | |
121 | } | |
09cbfeaf | 122 | put_page(page); |
c9e44410 KH |
123 | return ret; |
124 | } | |
355cfa73 | 125 | |
6a6ba831 HD |
126 | /* |
127 | * swapon tell device that all the old swap contents can be discarded, | |
128 | * to allow the swap device to optimize its wear-levelling. | |
129 | */ | |
130 | static int discard_swap(struct swap_info_struct *si) | |
131 | { | |
132 | struct swap_extent *se; | |
9625a5f2 HD |
133 | sector_t start_block; |
134 | sector_t nr_blocks; | |
6a6ba831 HD |
135 | int err = 0; |
136 | ||
9625a5f2 HD |
137 | /* Do not discard the swap header page! */ |
138 | se = &si->first_swap_extent; | |
139 | start_block = (se->start_block + 1) << (PAGE_SHIFT - 9); | |
140 | nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9); | |
141 | if (nr_blocks) { | |
142 | err = blkdev_issue_discard(si->bdev, start_block, | |
dd3932ed | 143 | nr_blocks, GFP_KERNEL, 0); |
9625a5f2 HD |
144 | if (err) |
145 | return err; | |
146 | cond_resched(); | |
147 | } | |
6a6ba831 | 148 | |
9625a5f2 HD |
149 | list_for_each_entry(se, &si->first_swap_extent.list, list) { |
150 | start_block = se->start_block << (PAGE_SHIFT - 9); | |
151 | nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); | |
6a6ba831 HD |
152 | |
153 | err = blkdev_issue_discard(si->bdev, start_block, | |
dd3932ed | 154 | nr_blocks, GFP_KERNEL, 0); |
6a6ba831 HD |
155 | if (err) |
156 | break; | |
157 | ||
158 | cond_resched(); | |
159 | } | |
160 | return err; /* That will often be -EOPNOTSUPP */ | |
161 | } | |
162 | ||
7992fde7 HD |
163 | /* |
164 | * swap allocation tell device that a cluster of swap can now be discarded, | |
165 | * to allow the swap device to optimize its wear-levelling. | |
166 | */ | |
167 | static void discard_swap_cluster(struct swap_info_struct *si, | |
168 | pgoff_t start_page, pgoff_t nr_pages) | |
169 | { | |
170 | struct swap_extent *se = si->curr_swap_extent; | |
171 | int found_extent = 0; | |
172 | ||
173 | while (nr_pages) { | |
7992fde7 HD |
174 | if (se->start_page <= start_page && |
175 | start_page < se->start_page + se->nr_pages) { | |
176 | pgoff_t offset = start_page - se->start_page; | |
177 | sector_t start_block = se->start_block + offset; | |
858a2990 | 178 | sector_t nr_blocks = se->nr_pages - offset; |
7992fde7 HD |
179 | |
180 | if (nr_blocks > nr_pages) | |
181 | nr_blocks = nr_pages; | |
182 | start_page += nr_blocks; | |
183 | nr_pages -= nr_blocks; | |
184 | ||
185 | if (!found_extent++) | |
186 | si->curr_swap_extent = se; | |
187 | ||
188 | start_block <<= PAGE_SHIFT - 9; | |
189 | nr_blocks <<= PAGE_SHIFT - 9; | |
190 | if (blkdev_issue_discard(si->bdev, start_block, | |
dd3932ed | 191 | nr_blocks, GFP_NOIO, 0)) |
7992fde7 HD |
192 | break; |
193 | } | |
194 | ||
a8ae4991 | 195 | se = list_next_entry(se, list); |
7992fde7 HD |
196 | } |
197 | } | |
198 | ||
048c27fd HD |
199 | #define SWAPFILE_CLUSTER 256 |
200 | #define LATENCY_LIMIT 256 | |
201 | ||
2a8f9449 SL |
202 | static inline void cluster_set_flag(struct swap_cluster_info *info, |
203 | unsigned int flag) | |
204 | { | |
205 | info->flags = flag; | |
206 | } | |
207 | ||
208 | static inline unsigned int cluster_count(struct swap_cluster_info *info) | |
209 | { | |
210 | return info->data; | |
211 | } | |
212 | ||
213 | static inline void cluster_set_count(struct swap_cluster_info *info, | |
214 | unsigned int c) | |
215 | { | |
216 | info->data = c; | |
217 | } | |
218 | ||
219 | static inline void cluster_set_count_flag(struct swap_cluster_info *info, | |
220 | unsigned int c, unsigned int f) | |
221 | { | |
222 | info->flags = f; | |
223 | info->data = c; | |
224 | } | |
225 | ||
226 | static inline unsigned int cluster_next(struct swap_cluster_info *info) | |
227 | { | |
228 | return info->data; | |
229 | } | |
230 | ||
231 | static inline void cluster_set_next(struct swap_cluster_info *info, | |
232 | unsigned int n) | |
233 | { | |
234 | info->data = n; | |
235 | } | |
236 | ||
237 | static inline void cluster_set_next_flag(struct swap_cluster_info *info, | |
238 | unsigned int n, unsigned int f) | |
239 | { | |
240 | info->flags = f; | |
241 | info->data = n; | |
242 | } | |
243 | ||
244 | static inline bool cluster_is_free(struct swap_cluster_info *info) | |
245 | { | |
246 | return info->flags & CLUSTER_FLAG_FREE; | |
247 | } | |
248 | ||
249 | static inline bool cluster_is_null(struct swap_cluster_info *info) | |
250 | { | |
251 | return info->flags & CLUSTER_FLAG_NEXT_NULL; | |
252 | } | |
253 | ||
254 | static inline void cluster_set_null(struct swap_cluster_info *info) | |
255 | { | |
256 | info->flags = CLUSTER_FLAG_NEXT_NULL; | |
257 | info->data = 0; | |
258 | } | |
259 | ||
6b534915 HY |
260 | static inline bool cluster_list_empty(struct swap_cluster_list *list) |
261 | { | |
262 | return cluster_is_null(&list->head); | |
263 | } | |
264 | ||
265 | static inline unsigned int cluster_list_first(struct swap_cluster_list *list) | |
266 | { | |
267 | return cluster_next(&list->head); | |
268 | } | |
269 | ||
270 | static void cluster_list_init(struct swap_cluster_list *list) | |
271 | { | |
272 | cluster_set_null(&list->head); | |
273 | cluster_set_null(&list->tail); | |
274 | } | |
275 | ||
276 | static void cluster_list_add_tail(struct swap_cluster_list *list, | |
277 | struct swap_cluster_info *ci, | |
278 | unsigned int idx) | |
279 | { | |
280 | if (cluster_list_empty(list)) { | |
281 | cluster_set_next_flag(&list->head, idx, 0); | |
282 | cluster_set_next_flag(&list->tail, idx, 0); | |
283 | } else { | |
284 | unsigned int tail = cluster_next(&list->tail); | |
285 | ||
286 | cluster_set_next(&ci[tail], idx); | |
287 | cluster_set_next_flag(&list->tail, idx, 0); | |
288 | } | |
289 | } | |
290 | ||
291 | static unsigned int cluster_list_del_first(struct swap_cluster_list *list, | |
292 | struct swap_cluster_info *ci) | |
293 | { | |
294 | unsigned int idx; | |
295 | ||
296 | idx = cluster_next(&list->head); | |
297 | if (cluster_next(&list->tail) == idx) { | |
298 | cluster_set_null(&list->head); | |
299 | cluster_set_null(&list->tail); | |
300 | } else | |
301 | cluster_set_next_flag(&list->head, | |
302 | cluster_next(&ci[idx]), 0); | |
303 | ||
304 | return idx; | |
305 | } | |
306 | ||
815c2c54 SL |
307 | /* Add a cluster to discard list and schedule it to do discard */ |
308 | static void swap_cluster_schedule_discard(struct swap_info_struct *si, | |
309 | unsigned int idx) | |
310 | { | |
311 | /* | |
312 | * If scan_swap_map() can't find a free cluster, it will check | |
313 | * si->swap_map directly. To make sure the discarding cluster isn't | |
314 | * taken by scan_swap_map(), mark the swap entries bad (occupied). It | |
315 | * will be cleared after discard | |
316 | */ | |
317 | memset(si->swap_map + idx * SWAPFILE_CLUSTER, | |
318 | SWAP_MAP_BAD, SWAPFILE_CLUSTER); | |
319 | ||
6b534915 | 320 | cluster_list_add_tail(&si->discard_clusters, si->cluster_info, idx); |
815c2c54 SL |
321 | |
322 | schedule_work(&si->discard_work); | |
323 | } | |
324 | ||
325 | /* | |
326 | * Doing discard actually. After a cluster discard is finished, the cluster | |
327 | * will be added to free cluster list. caller should hold si->lock. | |
328 | */ | |
329 | static void swap_do_scheduled_discard(struct swap_info_struct *si) | |
330 | { | |
331 | struct swap_cluster_info *info; | |
332 | unsigned int idx; | |
333 | ||
334 | info = si->cluster_info; | |
335 | ||
6b534915 HY |
336 | while (!cluster_list_empty(&si->discard_clusters)) { |
337 | idx = cluster_list_del_first(&si->discard_clusters, info); | |
815c2c54 SL |
338 | spin_unlock(&si->lock); |
339 | ||
340 | discard_swap_cluster(si, idx * SWAPFILE_CLUSTER, | |
341 | SWAPFILE_CLUSTER); | |
342 | ||
343 | spin_lock(&si->lock); | |
344 | cluster_set_flag(&info[idx], CLUSTER_FLAG_FREE); | |
6b534915 | 345 | cluster_list_add_tail(&si->free_clusters, info, idx); |
815c2c54 SL |
346 | memset(si->swap_map + idx * SWAPFILE_CLUSTER, |
347 | 0, SWAPFILE_CLUSTER); | |
348 | } | |
349 | } | |
350 | ||
351 | static void swap_discard_work(struct work_struct *work) | |
352 | { | |
353 | struct swap_info_struct *si; | |
354 | ||
355 | si = container_of(work, struct swap_info_struct, discard_work); | |
356 | ||
357 | spin_lock(&si->lock); | |
358 | swap_do_scheduled_discard(si); | |
359 | spin_unlock(&si->lock); | |
360 | } | |
361 | ||
2a8f9449 SL |
362 | /* |
363 | * The cluster corresponding to page_nr will be used. The cluster will be | |
364 | * removed from free cluster list and its usage counter will be increased. | |
365 | */ | |
366 | static void inc_cluster_info_page(struct swap_info_struct *p, | |
367 | struct swap_cluster_info *cluster_info, unsigned long page_nr) | |
368 | { | |
369 | unsigned long idx = page_nr / SWAPFILE_CLUSTER; | |
370 | ||
371 | if (!cluster_info) | |
372 | return; | |
373 | if (cluster_is_free(&cluster_info[idx])) { | |
6b534915 HY |
374 | VM_BUG_ON(cluster_list_first(&p->free_clusters) != idx); |
375 | cluster_list_del_first(&p->free_clusters, cluster_info); | |
2a8f9449 SL |
376 | cluster_set_count_flag(&cluster_info[idx], 0, 0); |
377 | } | |
378 | ||
379 | VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER); | |
380 | cluster_set_count(&cluster_info[idx], | |
381 | cluster_count(&cluster_info[idx]) + 1); | |
382 | } | |
383 | ||
384 | /* | |
385 | * The cluster corresponding to page_nr decreases one usage. If the usage | |
386 | * counter becomes 0, which means no page in the cluster is in using, we can | |
387 | * optionally discard the cluster and add it to free cluster list. | |
388 | */ | |
389 | static void dec_cluster_info_page(struct swap_info_struct *p, | |
390 | struct swap_cluster_info *cluster_info, unsigned long page_nr) | |
391 | { | |
392 | unsigned long idx = page_nr / SWAPFILE_CLUSTER; | |
393 | ||
394 | if (!cluster_info) | |
395 | return; | |
396 | ||
397 | VM_BUG_ON(cluster_count(&cluster_info[idx]) == 0); | |
398 | cluster_set_count(&cluster_info[idx], | |
399 | cluster_count(&cluster_info[idx]) - 1); | |
400 | ||
401 | if (cluster_count(&cluster_info[idx]) == 0) { | |
815c2c54 SL |
402 | /* |
403 | * If the swap is discardable, prepare discard the cluster | |
404 | * instead of free it immediately. The cluster will be freed | |
405 | * after discard. | |
406 | */ | |
edfe23da SL |
407 | if ((p->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == |
408 | (SWP_WRITEOK | SWP_PAGE_DISCARD)) { | |
815c2c54 SL |
409 | swap_cluster_schedule_discard(p, idx); |
410 | return; | |
411 | } | |
412 | ||
2a8f9449 | 413 | cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE); |
6b534915 | 414 | cluster_list_add_tail(&p->free_clusters, cluster_info, idx); |
2a8f9449 SL |
415 | } |
416 | } | |
417 | ||
418 | /* | |
419 | * It's possible scan_swap_map() uses a free cluster in the middle of free | |
420 | * cluster list. Avoiding such abuse to avoid list corruption. | |
421 | */ | |
ebc2a1a6 SL |
422 | static bool |
423 | scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si, | |
2a8f9449 SL |
424 | unsigned long offset) |
425 | { | |
ebc2a1a6 SL |
426 | struct percpu_cluster *percpu_cluster; |
427 | bool conflict; | |
428 | ||
2a8f9449 | 429 | offset /= SWAPFILE_CLUSTER; |
6b534915 HY |
430 | conflict = !cluster_list_empty(&si->free_clusters) && |
431 | offset != cluster_list_first(&si->free_clusters) && | |
2a8f9449 | 432 | cluster_is_free(&si->cluster_info[offset]); |
ebc2a1a6 SL |
433 | |
434 | if (!conflict) | |
435 | return false; | |
436 | ||
437 | percpu_cluster = this_cpu_ptr(si->percpu_cluster); | |
438 | cluster_set_null(&percpu_cluster->index); | |
439 | return true; | |
440 | } | |
441 | ||
442 | /* | |
443 | * Try to get a swap entry from current cpu's swap entry pool (a cluster). This | |
444 | * might involve allocating a new cluster for current CPU too. | |
445 | */ | |
446 | static void scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, | |
447 | unsigned long *offset, unsigned long *scan_base) | |
448 | { | |
449 | struct percpu_cluster *cluster; | |
450 | bool found_free; | |
451 | unsigned long tmp; | |
452 | ||
453 | new_cluster: | |
454 | cluster = this_cpu_ptr(si->percpu_cluster); | |
455 | if (cluster_is_null(&cluster->index)) { | |
6b534915 HY |
456 | if (!cluster_list_empty(&si->free_clusters)) { |
457 | cluster->index = si->free_clusters.head; | |
ebc2a1a6 SL |
458 | cluster->next = cluster_next(&cluster->index) * |
459 | SWAPFILE_CLUSTER; | |
6b534915 | 460 | } else if (!cluster_list_empty(&si->discard_clusters)) { |
ebc2a1a6 SL |
461 | /* |
462 | * we don't have free cluster but have some clusters in | |
463 | * discarding, do discard now and reclaim them | |
464 | */ | |
465 | swap_do_scheduled_discard(si); | |
466 | *scan_base = *offset = si->cluster_next; | |
467 | goto new_cluster; | |
468 | } else | |
469 | return; | |
470 | } | |
471 | ||
472 | found_free = false; | |
473 | ||
474 | /* | |
475 | * Other CPUs can use our cluster if they can't find a free cluster, | |
476 | * check if there is still free entry in the cluster | |
477 | */ | |
478 | tmp = cluster->next; | |
479 | while (tmp < si->max && tmp < (cluster_next(&cluster->index) + 1) * | |
480 | SWAPFILE_CLUSTER) { | |
481 | if (!si->swap_map[tmp]) { | |
482 | found_free = true; | |
483 | break; | |
484 | } | |
485 | tmp++; | |
486 | } | |
487 | if (!found_free) { | |
488 | cluster_set_null(&cluster->index); | |
489 | goto new_cluster; | |
490 | } | |
491 | cluster->next = tmp + 1; | |
492 | *offset = tmp; | |
493 | *scan_base = tmp; | |
2a8f9449 SL |
494 | } |
495 | ||
24b8ff7c CEB |
496 | static unsigned long scan_swap_map(struct swap_info_struct *si, |
497 | unsigned char usage) | |
1da177e4 | 498 | { |
ebebbbe9 | 499 | unsigned long offset; |
c60aa176 | 500 | unsigned long scan_base; |
7992fde7 | 501 | unsigned long last_in_cluster = 0; |
048c27fd | 502 | int latency_ration = LATENCY_LIMIT; |
7dfad418 | 503 | |
886bb7e9 | 504 | /* |
7dfad418 HD |
505 | * We try to cluster swap pages by allocating them sequentially |
506 | * in swap. Once we've allocated SWAPFILE_CLUSTER pages this | |
507 | * way, however, we resort to first-free allocation, starting | |
508 | * a new cluster. This prevents us from scattering swap pages | |
509 | * all over the entire swap partition, so that we reduce | |
510 | * overall disk seek times between swap pages. -- sct | |
511 | * But we do now try to find an empty cluster. -Andrea | |
c60aa176 | 512 | * And we let swap pages go all over an SSD partition. Hugh |
7dfad418 HD |
513 | */ |
514 | ||
52b7efdb | 515 | si->flags += SWP_SCANNING; |
c60aa176 | 516 | scan_base = offset = si->cluster_next; |
ebebbbe9 | 517 | |
ebc2a1a6 SL |
518 | /* SSD algorithm */ |
519 | if (si->cluster_info) { | |
520 | scan_swap_map_try_ssd_cluster(si, &offset, &scan_base); | |
521 | goto checks; | |
522 | } | |
523 | ||
ebebbbe9 HD |
524 | if (unlikely(!si->cluster_nr--)) { |
525 | if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { | |
526 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
527 | goto checks; | |
528 | } | |
2a8f9449 | 529 | |
ec8acf20 | 530 | spin_unlock(&si->lock); |
7dfad418 | 531 | |
c60aa176 HD |
532 | /* |
533 | * If seek is expensive, start searching for new cluster from | |
534 | * start of partition, to minimize the span of allocated swap. | |
50088c44 CY |
535 | * If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info |
536 | * case, just handled by scan_swap_map_try_ssd_cluster() above. | |
c60aa176 | 537 | */ |
50088c44 | 538 | scan_base = offset = si->lowest_bit; |
7dfad418 HD |
539 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
540 | ||
541 | /* Locate the first empty (unaligned) cluster */ | |
542 | for (; last_in_cluster <= si->highest_bit; offset++) { | |
1da177e4 | 543 | if (si->swap_map[offset]) |
7dfad418 HD |
544 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
545 | else if (offset == last_in_cluster) { | |
ec8acf20 | 546 | spin_lock(&si->lock); |
ebebbbe9 HD |
547 | offset -= SWAPFILE_CLUSTER - 1; |
548 | si->cluster_next = offset; | |
549 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
c60aa176 HD |
550 | goto checks; |
551 | } | |
552 | if (unlikely(--latency_ration < 0)) { | |
553 | cond_resched(); | |
554 | latency_ration = LATENCY_LIMIT; | |
555 | } | |
556 | } | |
557 | ||
558 | offset = scan_base; | |
ec8acf20 | 559 | spin_lock(&si->lock); |
ebebbbe9 | 560 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
1da177e4 | 561 | } |
7dfad418 | 562 | |
ebebbbe9 | 563 | checks: |
ebc2a1a6 SL |
564 | if (si->cluster_info) { |
565 | while (scan_swap_map_ssd_cluster_conflict(si, offset)) | |
566 | scan_swap_map_try_ssd_cluster(si, &offset, &scan_base); | |
567 | } | |
ebebbbe9 | 568 | if (!(si->flags & SWP_WRITEOK)) |
52b7efdb | 569 | goto no_page; |
7dfad418 HD |
570 | if (!si->highest_bit) |
571 | goto no_page; | |
ebebbbe9 | 572 | if (offset > si->highest_bit) |
c60aa176 | 573 | scan_base = offset = si->lowest_bit; |
c9e44410 | 574 | |
b73d7fce HD |
575 | /* reuse swap entry of cache-only swap if not busy. */ |
576 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { | |
c9e44410 | 577 | int swap_was_freed; |
ec8acf20 | 578 | spin_unlock(&si->lock); |
c9e44410 | 579 | swap_was_freed = __try_to_reclaim_swap(si, offset); |
ec8acf20 | 580 | spin_lock(&si->lock); |
c9e44410 KH |
581 | /* entry was freed successfully, try to use this again */ |
582 | if (swap_was_freed) | |
583 | goto checks; | |
584 | goto scan; /* check next one */ | |
585 | } | |
586 | ||
ebebbbe9 HD |
587 | if (si->swap_map[offset]) |
588 | goto scan; | |
589 | ||
590 | if (offset == si->lowest_bit) | |
591 | si->lowest_bit++; | |
592 | if (offset == si->highest_bit) | |
593 | si->highest_bit--; | |
594 | si->inuse_pages++; | |
595 | if (si->inuse_pages == si->pages) { | |
596 | si->lowest_bit = si->max; | |
597 | si->highest_bit = 0; | |
18ab4d4c DS |
598 | spin_lock(&swap_avail_lock); |
599 | plist_del(&si->avail_list, &swap_avail_head); | |
600 | spin_unlock(&swap_avail_lock); | |
1da177e4 | 601 | } |
253d553b | 602 | si->swap_map[offset] = usage; |
2a8f9449 | 603 | inc_cluster_info_page(si, si->cluster_info, offset); |
ebebbbe9 HD |
604 | si->cluster_next = offset + 1; |
605 | si->flags -= SWP_SCANNING; | |
7992fde7 | 606 | |
ebebbbe9 | 607 | return offset; |
7dfad418 | 608 | |
ebebbbe9 | 609 | scan: |
ec8acf20 | 610 | spin_unlock(&si->lock); |
7dfad418 | 611 | while (++offset <= si->highest_bit) { |
52b7efdb | 612 | if (!si->swap_map[offset]) { |
ec8acf20 | 613 | spin_lock(&si->lock); |
52b7efdb HD |
614 | goto checks; |
615 | } | |
c9e44410 | 616 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
ec8acf20 | 617 | spin_lock(&si->lock); |
c9e44410 KH |
618 | goto checks; |
619 | } | |
048c27fd HD |
620 | if (unlikely(--latency_ration < 0)) { |
621 | cond_resched(); | |
622 | latency_ration = LATENCY_LIMIT; | |
623 | } | |
7dfad418 | 624 | } |
c60aa176 | 625 | offset = si->lowest_bit; |
a5998061 | 626 | while (offset < scan_base) { |
c60aa176 | 627 | if (!si->swap_map[offset]) { |
ec8acf20 | 628 | spin_lock(&si->lock); |
c60aa176 HD |
629 | goto checks; |
630 | } | |
c9e44410 | 631 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
ec8acf20 | 632 | spin_lock(&si->lock); |
c9e44410 KH |
633 | goto checks; |
634 | } | |
c60aa176 HD |
635 | if (unlikely(--latency_ration < 0)) { |
636 | cond_resched(); | |
637 | latency_ration = LATENCY_LIMIT; | |
638 | } | |
a5998061 | 639 | offset++; |
c60aa176 | 640 | } |
ec8acf20 | 641 | spin_lock(&si->lock); |
7dfad418 HD |
642 | |
643 | no_page: | |
52b7efdb | 644 | si->flags -= SWP_SCANNING; |
1da177e4 LT |
645 | return 0; |
646 | } | |
647 | ||
648 | swp_entry_t get_swap_page(void) | |
649 | { | |
adfab836 | 650 | struct swap_info_struct *si, *next; |
fb4f88dc | 651 | pgoff_t offset; |
1da177e4 | 652 | |
ec8acf20 | 653 | if (atomic_long_read(&nr_swap_pages) <= 0) |
fb4f88dc | 654 | goto noswap; |
ec8acf20 | 655 | atomic_long_dec(&nr_swap_pages); |
fb4f88dc | 656 | |
18ab4d4c DS |
657 | spin_lock(&swap_avail_lock); |
658 | ||
659 | start_over: | |
660 | plist_for_each_entry_safe(si, next, &swap_avail_head, avail_list) { | |
661 | /* requeue si to after same-priority siblings */ | |
662 | plist_requeue(&si->avail_list, &swap_avail_head); | |
663 | spin_unlock(&swap_avail_lock); | |
ec8acf20 | 664 | spin_lock(&si->lock); |
adfab836 | 665 | if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) { |
18ab4d4c DS |
666 | spin_lock(&swap_avail_lock); |
667 | if (plist_node_empty(&si->avail_list)) { | |
668 | spin_unlock(&si->lock); | |
669 | goto nextsi; | |
670 | } | |
671 | WARN(!si->highest_bit, | |
672 | "swap_info %d in list but !highest_bit\n", | |
673 | si->type); | |
674 | WARN(!(si->flags & SWP_WRITEOK), | |
675 | "swap_info %d in list but !SWP_WRITEOK\n", | |
676 | si->type); | |
677 | plist_del(&si->avail_list, &swap_avail_head); | |
ec8acf20 | 678 | spin_unlock(&si->lock); |
18ab4d4c | 679 | goto nextsi; |
ec8acf20 | 680 | } |
fb4f88dc | 681 | |
355cfa73 | 682 | /* This is called for allocating swap entry for cache */ |
253d553b | 683 | offset = scan_swap_map(si, SWAP_HAS_CACHE); |
ec8acf20 SL |
684 | spin_unlock(&si->lock); |
685 | if (offset) | |
adfab836 | 686 | return swp_entry(si->type, offset); |
18ab4d4c DS |
687 | pr_debug("scan_swap_map of si %d failed to find offset\n", |
688 | si->type); | |
689 | spin_lock(&swap_avail_lock); | |
690 | nextsi: | |
adfab836 DS |
691 | /* |
692 | * if we got here, it's likely that si was almost full before, | |
693 | * and since scan_swap_map() can drop the si->lock, multiple | |
694 | * callers probably all tried to get a page from the same si | |
18ab4d4c DS |
695 | * and it filled up before we could get one; or, the si filled |
696 | * up between us dropping swap_avail_lock and taking si->lock. | |
697 | * Since we dropped the swap_avail_lock, the swap_avail_head | |
698 | * list may have been modified; so if next is still in the | |
699 | * swap_avail_head list then try it, otherwise start over. | |
adfab836 | 700 | */ |
18ab4d4c DS |
701 | if (plist_node_empty(&next->avail_list)) |
702 | goto start_over; | |
1da177e4 | 703 | } |
fb4f88dc | 704 | |
18ab4d4c DS |
705 | spin_unlock(&swap_avail_lock); |
706 | ||
ec8acf20 | 707 | atomic_long_inc(&nr_swap_pages); |
fb4f88dc | 708 | noswap: |
fb4f88dc | 709 | return (swp_entry_t) {0}; |
1da177e4 LT |
710 | } |
711 | ||
2de1a7e4 | 712 | /* The only caller of this function is now suspend routine */ |
910321ea HD |
713 | swp_entry_t get_swap_page_of_type(int type) |
714 | { | |
715 | struct swap_info_struct *si; | |
716 | pgoff_t offset; | |
717 | ||
910321ea | 718 | si = swap_info[type]; |
ec8acf20 | 719 | spin_lock(&si->lock); |
910321ea | 720 | if (si && (si->flags & SWP_WRITEOK)) { |
ec8acf20 | 721 | atomic_long_dec(&nr_swap_pages); |
910321ea HD |
722 | /* This is called for allocating swap entry, not cache */ |
723 | offset = scan_swap_map(si, 1); | |
724 | if (offset) { | |
ec8acf20 | 725 | spin_unlock(&si->lock); |
910321ea HD |
726 | return swp_entry(type, offset); |
727 | } | |
ec8acf20 | 728 | atomic_long_inc(&nr_swap_pages); |
910321ea | 729 | } |
ec8acf20 | 730 | spin_unlock(&si->lock); |
910321ea HD |
731 | return (swp_entry_t) {0}; |
732 | } | |
733 | ||
73c34b6a | 734 | static struct swap_info_struct *swap_info_get(swp_entry_t entry) |
1da177e4 | 735 | { |
73c34b6a | 736 | struct swap_info_struct *p; |
1da177e4 LT |
737 | unsigned long offset, type; |
738 | ||
739 | if (!entry.val) | |
740 | goto out; | |
741 | type = swp_type(entry); | |
742 | if (type >= nr_swapfiles) | |
743 | goto bad_nofile; | |
efa90a98 | 744 | p = swap_info[type]; |
1da177e4 LT |
745 | if (!(p->flags & SWP_USED)) |
746 | goto bad_device; | |
747 | offset = swp_offset(entry); | |
748 | if (offset >= p->max) | |
749 | goto bad_offset; | |
750 | if (!p->swap_map[offset]) | |
751 | goto bad_free; | |
ec8acf20 | 752 | spin_lock(&p->lock); |
1da177e4 LT |
753 | return p; |
754 | ||
755 | bad_free: | |
465c47fd | 756 | pr_err("swap_free: %s%08lx\n", Unused_offset, entry.val); |
1da177e4 LT |
757 | goto out; |
758 | bad_offset: | |
465c47fd | 759 | pr_err("swap_free: %s%08lx\n", Bad_offset, entry.val); |
1da177e4 LT |
760 | goto out; |
761 | bad_device: | |
465c47fd | 762 | pr_err("swap_free: %s%08lx\n", Unused_file, entry.val); |
1da177e4 LT |
763 | goto out; |
764 | bad_nofile: | |
465c47fd | 765 | pr_err("swap_free: %s%08lx\n", Bad_file, entry.val); |
1da177e4 LT |
766 | out: |
767 | return NULL; | |
886bb7e9 | 768 | } |
1da177e4 | 769 | |
8d69aaee HD |
770 | static unsigned char swap_entry_free(struct swap_info_struct *p, |
771 | swp_entry_t entry, unsigned char usage) | |
1da177e4 | 772 | { |
253d553b | 773 | unsigned long offset = swp_offset(entry); |
8d69aaee HD |
774 | unsigned char count; |
775 | unsigned char has_cache; | |
355cfa73 | 776 | |
253d553b HD |
777 | count = p->swap_map[offset]; |
778 | has_cache = count & SWAP_HAS_CACHE; | |
779 | count &= ~SWAP_HAS_CACHE; | |
355cfa73 | 780 | |
253d553b | 781 | if (usage == SWAP_HAS_CACHE) { |
355cfa73 | 782 | VM_BUG_ON(!has_cache); |
253d553b | 783 | has_cache = 0; |
aaa46865 HD |
784 | } else if (count == SWAP_MAP_SHMEM) { |
785 | /* | |
786 | * Or we could insist on shmem.c using a special | |
787 | * swap_shmem_free() and free_shmem_swap_and_cache()... | |
788 | */ | |
789 | count = 0; | |
570a335b HD |
790 | } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { |
791 | if (count == COUNT_CONTINUED) { | |
792 | if (swap_count_continued(p, offset, count)) | |
793 | count = SWAP_MAP_MAX | COUNT_CONTINUED; | |
794 | else | |
795 | count = SWAP_MAP_MAX; | |
796 | } else | |
797 | count--; | |
798 | } | |
253d553b | 799 | |
253d553b HD |
800 | usage = count | has_cache; |
801 | p->swap_map[offset] = usage; | |
355cfa73 | 802 | |
355cfa73 | 803 | /* free if no reference */ |
253d553b | 804 | if (!usage) { |
37e84351 | 805 | mem_cgroup_uncharge_swap(entry); |
2a8f9449 | 806 | dec_cluster_info_page(p, p->cluster_info, offset); |
355cfa73 KH |
807 | if (offset < p->lowest_bit) |
808 | p->lowest_bit = offset; | |
18ab4d4c DS |
809 | if (offset > p->highest_bit) { |
810 | bool was_full = !p->highest_bit; | |
355cfa73 | 811 | p->highest_bit = offset; |
18ab4d4c DS |
812 | if (was_full && (p->flags & SWP_WRITEOK)) { |
813 | spin_lock(&swap_avail_lock); | |
814 | WARN_ON(!plist_node_empty(&p->avail_list)); | |
815 | if (plist_node_empty(&p->avail_list)) | |
816 | plist_add(&p->avail_list, | |
817 | &swap_avail_head); | |
818 | spin_unlock(&swap_avail_lock); | |
819 | } | |
820 | } | |
ec8acf20 | 821 | atomic_long_inc(&nr_swap_pages); |
355cfa73 | 822 | p->inuse_pages--; |
38b5faf4 | 823 | frontswap_invalidate_page(p->type, offset); |
73744923 MG |
824 | if (p->flags & SWP_BLKDEV) { |
825 | struct gendisk *disk = p->bdev->bd_disk; | |
826 | if (disk->fops->swap_slot_free_notify) | |
827 | disk->fops->swap_slot_free_notify(p->bdev, | |
828 | offset); | |
829 | } | |
1da177e4 | 830 | } |
253d553b HD |
831 | |
832 | return usage; | |
1da177e4 LT |
833 | } |
834 | ||
835 | /* | |
2de1a7e4 | 836 | * Caller has made sure that the swap device corresponding to entry |
1da177e4 LT |
837 | * is still around or has not been recycled. |
838 | */ | |
839 | void swap_free(swp_entry_t entry) | |
840 | { | |
73c34b6a | 841 | struct swap_info_struct *p; |
1da177e4 LT |
842 | |
843 | p = swap_info_get(entry); | |
844 | if (p) { | |
253d553b | 845 | swap_entry_free(p, entry, 1); |
ec8acf20 | 846 | spin_unlock(&p->lock); |
1da177e4 LT |
847 | } |
848 | } | |
849 | ||
cb4b86ba KH |
850 | /* |
851 | * Called after dropping swapcache to decrease refcnt to swap entries. | |
852 | */ | |
0a31bc97 | 853 | void swapcache_free(swp_entry_t entry) |
cb4b86ba | 854 | { |
355cfa73 KH |
855 | struct swap_info_struct *p; |
856 | ||
355cfa73 KH |
857 | p = swap_info_get(entry); |
858 | if (p) { | |
0a31bc97 | 859 | swap_entry_free(p, entry, SWAP_HAS_CACHE); |
ec8acf20 | 860 | spin_unlock(&p->lock); |
355cfa73 | 861 | } |
cb4b86ba KH |
862 | } |
863 | ||
1da177e4 | 864 | /* |
c475a8ab | 865 | * How many references to page are currently swapped out? |
570a335b HD |
866 | * This does not give an exact answer when swap count is continued, |
867 | * but does include the high COUNT_CONTINUED flag to allow for that. | |
1da177e4 | 868 | */ |
bde05d1c | 869 | int page_swapcount(struct page *page) |
1da177e4 | 870 | { |
c475a8ab HD |
871 | int count = 0; |
872 | struct swap_info_struct *p; | |
1da177e4 LT |
873 | swp_entry_t entry; |
874 | ||
4c21e2f2 | 875 | entry.val = page_private(page); |
1da177e4 LT |
876 | p = swap_info_get(entry); |
877 | if (p) { | |
355cfa73 | 878 | count = swap_count(p->swap_map[swp_offset(entry)]); |
ec8acf20 | 879 | spin_unlock(&p->lock); |
1da177e4 | 880 | } |
c475a8ab | 881 | return count; |
1da177e4 LT |
882 | } |
883 | ||
8334b962 MK |
884 | /* |
885 | * How many references to @entry are currently swapped out? | |
886 | * This considers COUNT_CONTINUED so it returns exact answer. | |
887 | */ | |
888 | int swp_swapcount(swp_entry_t entry) | |
889 | { | |
890 | int count, tmp_count, n; | |
891 | struct swap_info_struct *p; | |
892 | struct page *page; | |
893 | pgoff_t offset; | |
894 | unsigned char *map; | |
895 | ||
896 | p = swap_info_get(entry); | |
897 | if (!p) | |
898 | return 0; | |
899 | ||
900 | count = swap_count(p->swap_map[swp_offset(entry)]); | |
901 | if (!(count & COUNT_CONTINUED)) | |
902 | goto out; | |
903 | ||
904 | count &= ~COUNT_CONTINUED; | |
905 | n = SWAP_MAP_MAX + 1; | |
906 | ||
907 | offset = swp_offset(entry); | |
908 | page = vmalloc_to_page(p->swap_map + offset); | |
909 | offset &= ~PAGE_MASK; | |
910 | VM_BUG_ON(page_private(page) != SWP_CONTINUED); | |
911 | ||
912 | do { | |
a8ae4991 | 913 | page = list_next_entry(page, lru); |
8334b962 MK |
914 | map = kmap_atomic(page); |
915 | tmp_count = map[offset]; | |
916 | kunmap_atomic(map); | |
917 | ||
918 | count += (tmp_count & ~COUNT_CONTINUED) * n; | |
919 | n *= (SWAP_CONT_MAX + 1); | |
920 | } while (tmp_count & COUNT_CONTINUED); | |
921 | out: | |
922 | spin_unlock(&p->lock); | |
923 | return count; | |
924 | } | |
925 | ||
1da177e4 | 926 | /* |
7b1fe597 HD |
927 | * We can write to an anon page without COW if there are no other references |
928 | * to it. And as a side-effect, free up its swap: because the old content | |
929 | * on disk will never be read, and seeking back there to write new content | |
930 | * later would only waste time away from clustering. | |
6d0a07ed AA |
931 | * |
932 | * NOTE: total_mapcount should not be relied upon by the caller if | |
933 | * reuse_swap_page() returns false, but it may be always overwritten | |
934 | * (see the other implementation for CONFIG_SWAP=n). | |
1da177e4 | 935 | */ |
6d0a07ed | 936 | bool reuse_swap_page(struct page *page, int *total_mapcount) |
1da177e4 | 937 | { |
c475a8ab HD |
938 | int count; |
939 | ||
309381fe | 940 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
5ad64688 | 941 | if (unlikely(PageKsm(page))) |
6d0a07ed AA |
942 | return false; |
943 | count = page_trans_huge_mapcount(page, total_mapcount); | |
7b1fe597 | 944 | if (count <= 1 && PageSwapCache(page)) { |
c475a8ab | 945 | count += page_swapcount(page); |
f0571429 MK |
946 | if (count != 1) |
947 | goto out; | |
948 | if (!PageWriteback(page)) { | |
7b1fe597 HD |
949 | delete_from_swap_cache(page); |
950 | SetPageDirty(page); | |
f0571429 MK |
951 | } else { |
952 | swp_entry_t entry; | |
953 | struct swap_info_struct *p; | |
954 | ||
955 | entry.val = page_private(page); | |
956 | p = swap_info_get(entry); | |
957 | if (p->flags & SWP_STABLE_WRITES) { | |
958 | spin_unlock(&p->lock); | |
959 | return false; | |
960 | } | |
961 | spin_unlock(&p->lock); | |
7b1fe597 HD |
962 | } |
963 | } | |
f0571429 | 964 | out: |
5ad64688 | 965 | return count <= 1; |
1da177e4 LT |
966 | } |
967 | ||
968 | /* | |
a2c43eed HD |
969 | * If swap is getting full, or if there are no more mappings of this page, |
970 | * then try_to_free_swap is called to free its swap space. | |
1da177e4 | 971 | */ |
a2c43eed | 972 | int try_to_free_swap(struct page *page) |
1da177e4 | 973 | { |
309381fe | 974 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
1da177e4 LT |
975 | |
976 | if (!PageSwapCache(page)) | |
977 | return 0; | |
978 | if (PageWriteback(page)) | |
979 | return 0; | |
a2c43eed | 980 | if (page_swapcount(page)) |
1da177e4 LT |
981 | return 0; |
982 | ||
b73d7fce HD |
983 | /* |
984 | * Once hibernation has begun to create its image of memory, | |
985 | * there's a danger that one of the calls to try_to_free_swap() | |
986 | * - most probably a call from __try_to_reclaim_swap() while | |
987 | * hibernation is allocating its own swap pages for the image, | |
988 | * but conceivably even a call from memory reclaim - will free | |
989 | * the swap from a page which has already been recorded in the | |
990 | * image as a clean swapcache page, and then reuse its swap for | |
991 | * another page of the image. On waking from hibernation, the | |
992 | * original page might be freed under memory pressure, then | |
993 | * later read back in from swap, now with the wrong data. | |
994 | * | |
2de1a7e4 | 995 | * Hibernation suspends storage while it is writing the image |
f90ac398 | 996 | * to disk so check that here. |
b73d7fce | 997 | */ |
f90ac398 | 998 | if (pm_suspended_storage()) |
b73d7fce HD |
999 | return 0; |
1000 | ||
a2c43eed HD |
1001 | delete_from_swap_cache(page); |
1002 | SetPageDirty(page); | |
1003 | return 1; | |
68a22394 RR |
1004 | } |
1005 | ||
1da177e4 LT |
1006 | /* |
1007 | * Free the swap entry like above, but also try to | |
1008 | * free the page cache entry if it is the last user. | |
1009 | */ | |
2509ef26 | 1010 | int free_swap_and_cache(swp_entry_t entry) |
1da177e4 | 1011 | { |
2509ef26 | 1012 | struct swap_info_struct *p; |
1da177e4 LT |
1013 | struct page *page = NULL; |
1014 | ||
a7420aa5 | 1015 | if (non_swap_entry(entry)) |
2509ef26 | 1016 | return 1; |
0697212a | 1017 | |
1da177e4 LT |
1018 | p = swap_info_get(entry); |
1019 | if (p) { | |
253d553b | 1020 | if (swap_entry_free(p, entry, 1) == SWAP_HAS_CACHE) { |
33806f06 | 1021 | page = find_get_page(swap_address_space(entry), |
f6ab1f7f | 1022 | swp_offset(entry)); |
8413ac9d | 1023 | if (page && !trylock_page(page)) { |
09cbfeaf | 1024 | put_page(page); |
93fac704 NP |
1025 | page = NULL; |
1026 | } | |
1027 | } | |
ec8acf20 | 1028 | spin_unlock(&p->lock); |
1da177e4 LT |
1029 | } |
1030 | if (page) { | |
a2c43eed HD |
1031 | /* |
1032 | * Not mapped elsewhere, or swap space full? Free it! | |
1033 | * Also recheck PageSwapCache now page is locked (above). | |
1034 | */ | |
93fac704 | 1035 | if (PageSwapCache(page) && !PageWriteback(page) && |
5ccc5aba | 1036 | (!page_mapped(page) || mem_cgroup_swap_full(page))) { |
1da177e4 LT |
1037 | delete_from_swap_cache(page); |
1038 | SetPageDirty(page); | |
1039 | } | |
1040 | unlock_page(page); | |
09cbfeaf | 1041 | put_page(page); |
1da177e4 | 1042 | } |
2509ef26 | 1043 | return p != NULL; |
1da177e4 LT |
1044 | } |
1045 | ||
b0cb1a19 | 1046 | #ifdef CONFIG_HIBERNATION |
f577eb30 | 1047 | /* |
915bae9e | 1048 | * Find the swap type that corresponds to given device (if any). |
f577eb30 | 1049 | * |
915bae9e RW |
1050 | * @offset - number of the PAGE_SIZE-sized block of the device, starting |
1051 | * from 0, in which the swap header is expected to be located. | |
1052 | * | |
1053 | * This is needed for the suspend to disk (aka swsusp). | |
f577eb30 | 1054 | */ |
7bf23687 | 1055 | int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) |
f577eb30 | 1056 | { |
915bae9e | 1057 | struct block_device *bdev = NULL; |
efa90a98 | 1058 | int type; |
f577eb30 | 1059 | |
915bae9e RW |
1060 | if (device) |
1061 | bdev = bdget(device); | |
1062 | ||
f577eb30 | 1063 | spin_lock(&swap_lock); |
efa90a98 HD |
1064 | for (type = 0; type < nr_swapfiles; type++) { |
1065 | struct swap_info_struct *sis = swap_info[type]; | |
f577eb30 | 1066 | |
915bae9e | 1067 | if (!(sis->flags & SWP_WRITEOK)) |
f577eb30 | 1068 | continue; |
b6b5bce3 | 1069 | |
915bae9e | 1070 | if (!bdev) { |
7bf23687 | 1071 | if (bdev_p) |
dddac6a7 | 1072 | *bdev_p = bdgrab(sis->bdev); |
7bf23687 | 1073 | |
6e1819d6 | 1074 | spin_unlock(&swap_lock); |
efa90a98 | 1075 | return type; |
6e1819d6 | 1076 | } |
915bae9e | 1077 | if (bdev == sis->bdev) { |
9625a5f2 | 1078 | struct swap_extent *se = &sis->first_swap_extent; |
915bae9e | 1079 | |
915bae9e | 1080 | if (se->start_block == offset) { |
7bf23687 | 1081 | if (bdev_p) |
dddac6a7 | 1082 | *bdev_p = bdgrab(sis->bdev); |
7bf23687 | 1083 | |
915bae9e RW |
1084 | spin_unlock(&swap_lock); |
1085 | bdput(bdev); | |
efa90a98 | 1086 | return type; |
915bae9e | 1087 | } |
f577eb30 RW |
1088 | } |
1089 | } | |
1090 | spin_unlock(&swap_lock); | |
915bae9e RW |
1091 | if (bdev) |
1092 | bdput(bdev); | |
1093 | ||
f577eb30 RW |
1094 | return -ENODEV; |
1095 | } | |
1096 | ||
73c34b6a HD |
1097 | /* |
1098 | * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev | |
1099 | * corresponding to given index in swap_info (swap type). | |
1100 | */ | |
1101 | sector_t swapdev_block(int type, pgoff_t offset) | |
1102 | { | |
1103 | struct block_device *bdev; | |
1104 | ||
1105 | if ((unsigned int)type >= nr_swapfiles) | |
1106 | return 0; | |
1107 | if (!(swap_info[type]->flags & SWP_WRITEOK)) | |
1108 | return 0; | |
d4906e1a | 1109 | return map_swap_entry(swp_entry(type, offset), &bdev); |
73c34b6a HD |
1110 | } |
1111 | ||
f577eb30 RW |
1112 | /* |
1113 | * Return either the total number of swap pages of given type, or the number | |
1114 | * of free pages of that type (depending on @free) | |
1115 | * | |
1116 | * This is needed for software suspend | |
1117 | */ | |
1118 | unsigned int count_swap_pages(int type, int free) | |
1119 | { | |
1120 | unsigned int n = 0; | |
1121 | ||
efa90a98 HD |
1122 | spin_lock(&swap_lock); |
1123 | if ((unsigned int)type < nr_swapfiles) { | |
1124 | struct swap_info_struct *sis = swap_info[type]; | |
1125 | ||
ec8acf20 | 1126 | spin_lock(&sis->lock); |
efa90a98 HD |
1127 | if (sis->flags & SWP_WRITEOK) { |
1128 | n = sis->pages; | |
f577eb30 | 1129 | if (free) |
efa90a98 | 1130 | n -= sis->inuse_pages; |
f577eb30 | 1131 | } |
ec8acf20 | 1132 | spin_unlock(&sis->lock); |
f577eb30 | 1133 | } |
efa90a98 | 1134 | spin_unlock(&swap_lock); |
f577eb30 RW |
1135 | return n; |
1136 | } | |
73c34b6a | 1137 | #endif /* CONFIG_HIBERNATION */ |
f577eb30 | 1138 | |
9f8bdb3f | 1139 | static inline int pte_same_as_swp(pte_t pte, pte_t swp_pte) |
179ef71c | 1140 | { |
9f8bdb3f | 1141 | return pte_same(pte_swp_clear_soft_dirty(pte), swp_pte); |
179ef71c CG |
1142 | } |
1143 | ||
1da177e4 | 1144 | /* |
72866f6f HD |
1145 | * No need to decide whether this PTE shares the swap entry with others, |
1146 | * just let do_wp_page work it out if a write is requested later - to | |
1147 | * force COW, vm_page_prot omits write permission from any private vma. | |
1da177e4 | 1148 | */ |
044d66c1 | 1149 | static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
1da177e4 LT |
1150 | unsigned long addr, swp_entry_t entry, struct page *page) |
1151 | { | |
9e16b7fb | 1152 | struct page *swapcache; |
72835c86 | 1153 | struct mem_cgroup *memcg; |
044d66c1 HD |
1154 | spinlock_t *ptl; |
1155 | pte_t *pte; | |
1156 | int ret = 1; | |
1157 | ||
9e16b7fb HD |
1158 | swapcache = page; |
1159 | page = ksm_might_need_to_copy(page, vma, addr); | |
1160 | if (unlikely(!page)) | |
1161 | return -ENOMEM; | |
1162 | ||
f627c2f5 KS |
1163 | if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, |
1164 | &memcg, false)) { | |
044d66c1 | 1165 | ret = -ENOMEM; |
85d9fc89 KH |
1166 | goto out_nolock; |
1167 | } | |
044d66c1 HD |
1168 | |
1169 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); | |
9f8bdb3f | 1170 | if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) { |
f627c2f5 | 1171 | mem_cgroup_cancel_charge(page, memcg, false); |
044d66c1 HD |
1172 | ret = 0; |
1173 | goto out; | |
1174 | } | |
8a9f3ccd | 1175 | |
b084d435 | 1176 | dec_mm_counter(vma->vm_mm, MM_SWAPENTS); |
d559db08 | 1177 | inc_mm_counter(vma->vm_mm, MM_ANONPAGES); |
1da177e4 LT |
1178 | get_page(page); |
1179 | set_pte_at(vma->vm_mm, addr, pte, | |
1180 | pte_mkold(mk_pte(page, vma->vm_page_prot))); | |
00501b53 | 1181 | if (page == swapcache) { |
d281ee61 | 1182 | page_add_anon_rmap(page, vma, addr, false); |
f627c2f5 | 1183 | mem_cgroup_commit_charge(page, memcg, true, false); |
00501b53 | 1184 | } else { /* ksm created a completely new copy */ |
d281ee61 | 1185 | page_add_new_anon_rmap(page, vma, addr, false); |
f627c2f5 | 1186 | mem_cgroup_commit_charge(page, memcg, false, false); |
00501b53 JW |
1187 | lru_cache_add_active_or_unevictable(page, vma); |
1188 | } | |
1da177e4 LT |
1189 | swap_free(entry); |
1190 | /* | |
1191 | * Move the page to the active list so it is not | |
1192 | * immediately swapped out again after swapon. | |
1193 | */ | |
1194 | activate_page(page); | |
044d66c1 HD |
1195 | out: |
1196 | pte_unmap_unlock(pte, ptl); | |
85d9fc89 | 1197 | out_nolock: |
9e16b7fb HD |
1198 | if (page != swapcache) { |
1199 | unlock_page(page); | |
1200 | put_page(page); | |
1201 | } | |
044d66c1 | 1202 | return ret; |
1da177e4 LT |
1203 | } |
1204 | ||
1205 | static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, | |
1206 | unsigned long addr, unsigned long end, | |
1207 | swp_entry_t entry, struct page *page) | |
1208 | { | |
1da177e4 | 1209 | pte_t swp_pte = swp_entry_to_pte(entry); |
705e87c0 | 1210 | pte_t *pte; |
8a9f3ccd | 1211 | int ret = 0; |
1da177e4 | 1212 | |
044d66c1 HD |
1213 | /* |
1214 | * We don't actually need pte lock while scanning for swp_pte: since | |
1215 | * we hold page lock and mmap_sem, swp_pte cannot be inserted into the | |
1216 | * page table while we're scanning; though it could get zapped, and on | |
1217 | * some architectures (e.g. x86_32 with PAE) we might catch a glimpse | |
1218 | * of unmatched parts which look like swp_pte, so unuse_pte must | |
1219 | * recheck under pte lock. Scanning without pte lock lets it be | |
2de1a7e4 | 1220 | * preemptable whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE. |
044d66c1 HD |
1221 | */ |
1222 | pte = pte_offset_map(pmd, addr); | |
1da177e4 LT |
1223 | do { |
1224 | /* | |
1225 | * swapoff spends a _lot_ of time in this loop! | |
1226 | * Test inline before going to call unuse_pte. | |
1227 | */ | |
9f8bdb3f | 1228 | if (unlikely(pte_same_as_swp(*pte, swp_pte))) { |
044d66c1 HD |
1229 | pte_unmap(pte); |
1230 | ret = unuse_pte(vma, pmd, addr, entry, page); | |
1231 | if (ret) | |
1232 | goto out; | |
1233 | pte = pte_offset_map(pmd, addr); | |
1da177e4 LT |
1234 | } |
1235 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
044d66c1 HD |
1236 | pte_unmap(pte - 1); |
1237 | out: | |
8a9f3ccd | 1238 | return ret; |
1da177e4 LT |
1239 | } |
1240 | ||
1241 | static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, | |
1242 | unsigned long addr, unsigned long end, | |
1243 | swp_entry_t entry, struct page *page) | |
1244 | { | |
1245 | pmd_t *pmd; | |
1246 | unsigned long next; | |
8a9f3ccd | 1247 | int ret; |
1da177e4 LT |
1248 | |
1249 | pmd = pmd_offset(pud, addr); | |
1250 | do { | |
dc644a07 | 1251 | cond_resched(); |
1da177e4 | 1252 | next = pmd_addr_end(addr, end); |
1a5a9906 | 1253 | if (pmd_none_or_trans_huge_or_clear_bad(pmd)) |
1da177e4 | 1254 | continue; |
8a9f3ccd BS |
1255 | ret = unuse_pte_range(vma, pmd, addr, next, entry, page); |
1256 | if (ret) | |
1257 | return ret; | |
1da177e4 LT |
1258 | } while (pmd++, addr = next, addr != end); |
1259 | return 0; | |
1260 | } | |
1261 | ||
1262 | static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd, | |
1263 | unsigned long addr, unsigned long end, | |
1264 | swp_entry_t entry, struct page *page) | |
1265 | { | |
1266 | pud_t *pud; | |
1267 | unsigned long next; | |
8a9f3ccd | 1268 | int ret; |
1da177e4 LT |
1269 | |
1270 | pud = pud_offset(pgd, addr); | |
1271 | do { | |
1272 | next = pud_addr_end(addr, end); | |
1273 | if (pud_none_or_clear_bad(pud)) | |
1274 | continue; | |
8a9f3ccd BS |
1275 | ret = unuse_pmd_range(vma, pud, addr, next, entry, page); |
1276 | if (ret) | |
1277 | return ret; | |
1da177e4 LT |
1278 | } while (pud++, addr = next, addr != end); |
1279 | return 0; | |
1280 | } | |
1281 | ||
1282 | static int unuse_vma(struct vm_area_struct *vma, | |
1283 | swp_entry_t entry, struct page *page) | |
1284 | { | |
1285 | pgd_t *pgd; | |
1286 | unsigned long addr, end, next; | |
8a9f3ccd | 1287 | int ret; |
1da177e4 | 1288 | |
3ca7b3c5 | 1289 | if (page_anon_vma(page)) { |
1da177e4 LT |
1290 | addr = page_address_in_vma(page, vma); |
1291 | if (addr == -EFAULT) | |
1292 | return 0; | |
1293 | else | |
1294 | end = addr + PAGE_SIZE; | |
1295 | } else { | |
1296 | addr = vma->vm_start; | |
1297 | end = vma->vm_end; | |
1298 | } | |
1299 | ||
1300 | pgd = pgd_offset(vma->vm_mm, addr); | |
1301 | do { | |
1302 | next = pgd_addr_end(addr, end); | |
1303 | if (pgd_none_or_clear_bad(pgd)) | |
1304 | continue; | |
8a9f3ccd BS |
1305 | ret = unuse_pud_range(vma, pgd, addr, next, entry, page); |
1306 | if (ret) | |
1307 | return ret; | |
1da177e4 LT |
1308 | } while (pgd++, addr = next, addr != end); |
1309 | return 0; | |
1310 | } | |
1311 | ||
1312 | static int unuse_mm(struct mm_struct *mm, | |
1313 | swp_entry_t entry, struct page *page) | |
1314 | { | |
1315 | struct vm_area_struct *vma; | |
8a9f3ccd | 1316 | int ret = 0; |
1da177e4 LT |
1317 | |
1318 | if (!down_read_trylock(&mm->mmap_sem)) { | |
1319 | /* | |
7d03431c FLVC |
1320 | * Activate page so shrink_inactive_list is unlikely to unmap |
1321 | * its ptes while lock is dropped, so swapoff can make progress. | |
1da177e4 | 1322 | */ |
c475a8ab | 1323 | activate_page(page); |
1da177e4 LT |
1324 | unlock_page(page); |
1325 | down_read(&mm->mmap_sem); | |
1326 | lock_page(page); | |
1327 | } | |
1da177e4 | 1328 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
8a9f3ccd | 1329 | if (vma->anon_vma && (ret = unuse_vma(vma, entry, page))) |
1da177e4 | 1330 | break; |
dc644a07 | 1331 | cond_resched(); |
1da177e4 | 1332 | } |
1da177e4 | 1333 | up_read(&mm->mmap_sem); |
8a9f3ccd | 1334 | return (ret < 0)? ret: 0; |
1da177e4 LT |
1335 | } |
1336 | ||
1337 | /* | |
38b5faf4 DM |
1338 | * Scan swap_map (or frontswap_map if frontswap parameter is true) |
1339 | * from current position to next entry still in use. | |
1da177e4 LT |
1340 | * Recycle to start on reaching the end, returning 0 when empty. |
1341 | */ | |
6eb396dc | 1342 | static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
38b5faf4 | 1343 | unsigned int prev, bool frontswap) |
1da177e4 | 1344 | { |
6eb396dc HD |
1345 | unsigned int max = si->max; |
1346 | unsigned int i = prev; | |
8d69aaee | 1347 | unsigned char count; |
1da177e4 LT |
1348 | |
1349 | /* | |
5d337b91 | 1350 | * No need for swap_lock here: we're just looking |
1da177e4 LT |
1351 | * for whether an entry is in use, not modifying it; false |
1352 | * hits are okay, and sys_swapoff() has already prevented new | |
5d337b91 | 1353 | * allocations from this area (while holding swap_lock). |
1da177e4 LT |
1354 | */ |
1355 | for (;;) { | |
1356 | if (++i >= max) { | |
1357 | if (!prev) { | |
1358 | i = 0; | |
1359 | break; | |
1360 | } | |
1361 | /* | |
1362 | * No entries in use at top of swap_map, | |
1363 | * loop back to start and recheck there. | |
1364 | */ | |
1365 | max = prev + 1; | |
1366 | prev = 0; | |
1367 | i = 1; | |
1368 | } | |
4db0c3c2 | 1369 | count = READ_ONCE(si->swap_map[i]); |
355cfa73 | 1370 | if (count && swap_count(count) != SWAP_MAP_BAD) |
dc644a07 HD |
1371 | if (!frontswap || frontswap_test(si, i)) |
1372 | break; | |
1373 | if ((i % LATENCY_LIMIT) == 0) | |
1374 | cond_resched(); | |
1da177e4 LT |
1375 | } |
1376 | return i; | |
1377 | } | |
1378 | ||
1379 | /* | |
1380 | * We completely avoid races by reading each swap page in advance, | |
1381 | * and then search for the process using it. All the necessary | |
1382 | * page table adjustments can then be made atomically. | |
38b5faf4 DM |
1383 | * |
1384 | * if the boolean frontswap is true, only unuse pages_to_unuse pages; | |
1385 | * pages_to_unuse==0 means all pages; ignored if frontswap is false | |
1da177e4 | 1386 | */ |
38b5faf4 DM |
1387 | int try_to_unuse(unsigned int type, bool frontswap, |
1388 | unsigned long pages_to_unuse) | |
1da177e4 | 1389 | { |
efa90a98 | 1390 | struct swap_info_struct *si = swap_info[type]; |
1da177e4 | 1391 | struct mm_struct *start_mm; |
edfe23da SL |
1392 | volatile unsigned char *swap_map; /* swap_map is accessed without |
1393 | * locking. Mark it as volatile | |
1394 | * to prevent compiler doing | |
1395 | * something odd. | |
1396 | */ | |
8d69aaee | 1397 | unsigned char swcount; |
1da177e4 LT |
1398 | struct page *page; |
1399 | swp_entry_t entry; | |
6eb396dc | 1400 | unsigned int i = 0; |
1da177e4 | 1401 | int retval = 0; |
1da177e4 LT |
1402 | |
1403 | /* | |
1404 | * When searching mms for an entry, a good strategy is to | |
1405 | * start at the first mm we freed the previous entry from | |
1406 | * (though actually we don't notice whether we or coincidence | |
1407 | * freed the entry). Initialize this start_mm with a hold. | |
1408 | * | |
1409 | * A simpler strategy would be to start at the last mm we | |
1410 | * freed the previous entry from; but that would take less | |
1411 | * advantage of mmlist ordering, which clusters forked mms | |
1412 | * together, child after parent. If we race with dup_mmap(), we | |
1413 | * prefer to resolve parent before child, lest we miss entries | |
1414 | * duplicated after we scanned child: using last mm would invert | |
570a335b | 1415 | * that. |
1da177e4 LT |
1416 | */ |
1417 | start_mm = &init_mm; | |
1418 | atomic_inc(&init_mm.mm_users); | |
1419 | ||
1420 | /* | |
1421 | * Keep on scanning until all entries have gone. Usually, | |
1422 | * one pass through swap_map is enough, but not necessarily: | |
1423 | * there are races when an instance of an entry might be missed. | |
1424 | */ | |
38b5faf4 | 1425 | while ((i = find_next_to_unuse(si, i, frontswap)) != 0) { |
1da177e4 LT |
1426 | if (signal_pending(current)) { |
1427 | retval = -EINTR; | |
1428 | break; | |
1429 | } | |
1430 | ||
886bb7e9 | 1431 | /* |
1da177e4 LT |
1432 | * Get a page for the entry, using the existing swap |
1433 | * cache page if there is one. Otherwise, get a clean | |
886bb7e9 | 1434 | * page and read the swap into it. |
1da177e4 LT |
1435 | */ |
1436 | swap_map = &si->swap_map[i]; | |
1437 | entry = swp_entry(type, i); | |
02098fea HD |
1438 | page = read_swap_cache_async(entry, |
1439 | GFP_HIGHUSER_MOVABLE, NULL, 0); | |
1da177e4 LT |
1440 | if (!page) { |
1441 | /* | |
1442 | * Either swap_duplicate() failed because entry | |
1443 | * has been freed independently, and will not be | |
1444 | * reused since sys_swapoff() already disabled | |
1445 | * allocation from here, or alloc_page() failed. | |
1446 | */ | |
edfe23da SL |
1447 | swcount = *swap_map; |
1448 | /* | |
1449 | * We don't hold lock here, so the swap entry could be | |
1450 | * SWAP_MAP_BAD (when the cluster is discarding). | |
1451 | * Instead of fail out, We can just skip the swap | |
1452 | * entry because swapoff will wait for discarding | |
1453 | * finish anyway. | |
1454 | */ | |
1455 | if (!swcount || swcount == SWAP_MAP_BAD) | |
1da177e4 LT |
1456 | continue; |
1457 | retval = -ENOMEM; | |
1458 | break; | |
1459 | } | |
1460 | ||
1461 | /* | |
1462 | * Don't hold on to start_mm if it looks like exiting. | |
1463 | */ | |
1464 | if (atomic_read(&start_mm->mm_users) == 1) { | |
1465 | mmput(start_mm); | |
1466 | start_mm = &init_mm; | |
1467 | atomic_inc(&init_mm.mm_users); | |
1468 | } | |
1469 | ||
1470 | /* | |
1471 | * Wait for and lock page. When do_swap_page races with | |
1472 | * try_to_unuse, do_swap_page can handle the fault much | |
1473 | * faster than try_to_unuse can locate the entry. This | |
1474 | * apparently redundant "wait_on_page_locked" lets try_to_unuse | |
1475 | * defer to do_swap_page in such a case - in some tests, | |
1476 | * do_swap_page and try_to_unuse repeatedly compete. | |
1477 | */ | |
1478 | wait_on_page_locked(page); | |
1479 | wait_on_page_writeback(page); | |
1480 | lock_page(page); | |
1481 | wait_on_page_writeback(page); | |
1482 | ||
1483 | /* | |
1484 | * Remove all references to entry. | |
1da177e4 | 1485 | */ |
1da177e4 | 1486 | swcount = *swap_map; |
aaa46865 HD |
1487 | if (swap_count(swcount) == SWAP_MAP_SHMEM) { |
1488 | retval = shmem_unuse(entry, page); | |
1489 | /* page has already been unlocked and released */ | |
1490 | if (retval < 0) | |
1491 | break; | |
1492 | continue; | |
1da177e4 | 1493 | } |
aaa46865 HD |
1494 | if (swap_count(swcount) && start_mm != &init_mm) |
1495 | retval = unuse_mm(start_mm, entry, page); | |
1496 | ||
355cfa73 | 1497 | if (swap_count(*swap_map)) { |
1da177e4 LT |
1498 | int set_start_mm = (*swap_map >= swcount); |
1499 | struct list_head *p = &start_mm->mmlist; | |
1500 | struct mm_struct *new_start_mm = start_mm; | |
1501 | struct mm_struct *prev_mm = start_mm; | |
1502 | struct mm_struct *mm; | |
1503 | ||
1504 | atomic_inc(&new_start_mm->mm_users); | |
1505 | atomic_inc(&prev_mm->mm_users); | |
1506 | spin_lock(&mmlist_lock); | |
aaa46865 | 1507 | while (swap_count(*swap_map) && !retval && |
1da177e4 LT |
1508 | (p = p->next) != &start_mm->mmlist) { |
1509 | mm = list_entry(p, struct mm_struct, mmlist); | |
70af7c5c | 1510 | if (!atomic_inc_not_zero(&mm->mm_users)) |
1da177e4 | 1511 | continue; |
1da177e4 LT |
1512 | spin_unlock(&mmlist_lock); |
1513 | mmput(prev_mm); | |
1514 | prev_mm = mm; | |
1515 | ||
1516 | cond_resched(); | |
1517 | ||
1518 | swcount = *swap_map; | |
355cfa73 | 1519 | if (!swap_count(swcount)) /* any usage ? */ |
1da177e4 | 1520 | ; |
aaa46865 | 1521 | else if (mm == &init_mm) |
1da177e4 | 1522 | set_start_mm = 1; |
aaa46865 | 1523 | else |
1da177e4 | 1524 | retval = unuse_mm(mm, entry, page); |
355cfa73 | 1525 | |
32c5fc10 | 1526 | if (set_start_mm && *swap_map < swcount) { |
1da177e4 LT |
1527 | mmput(new_start_mm); |
1528 | atomic_inc(&mm->mm_users); | |
1529 | new_start_mm = mm; | |
1530 | set_start_mm = 0; | |
1531 | } | |
1532 | spin_lock(&mmlist_lock); | |
1533 | } | |
1534 | spin_unlock(&mmlist_lock); | |
1535 | mmput(prev_mm); | |
1536 | mmput(start_mm); | |
1537 | start_mm = new_start_mm; | |
1538 | } | |
1539 | if (retval) { | |
1540 | unlock_page(page); | |
09cbfeaf | 1541 | put_page(page); |
1da177e4 LT |
1542 | break; |
1543 | } | |
1544 | ||
1da177e4 LT |
1545 | /* |
1546 | * If a reference remains (rare), we would like to leave | |
1547 | * the page in the swap cache; but try_to_unmap could | |
1548 | * then re-duplicate the entry once we drop page lock, | |
1549 | * so we might loop indefinitely; also, that page could | |
1550 | * not be swapped out to other storage meanwhile. So: | |
1551 | * delete from cache even if there's another reference, | |
1552 | * after ensuring that the data has been saved to disk - | |
1553 | * since if the reference remains (rarer), it will be | |
1554 | * read from disk into another page. Splitting into two | |
1555 | * pages would be incorrect if swap supported "shared | |
1556 | * private" pages, but they are handled by tmpfs files. | |
5ad64688 HD |
1557 | * |
1558 | * Given how unuse_vma() targets one particular offset | |
1559 | * in an anon_vma, once the anon_vma has been determined, | |
1560 | * this splitting happens to be just what is needed to | |
1561 | * handle where KSM pages have been swapped out: re-reading | |
1562 | * is unnecessarily slow, but we can fix that later on. | |
1da177e4 | 1563 | */ |
355cfa73 KH |
1564 | if (swap_count(*swap_map) && |
1565 | PageDirty(page) && PageSwapCache(page)) { | |
1da177e4 LT |
1566 | struct writeback_control wbc = { |
1567 | .sync_mode = WB_SYNC_NONE, | |
1568 | }; | |
1569 | ||
1570 | swap_writepage(page, &wbc); | |
1571 | lock_page(page); | |
1572 | wait_on_page_writeback(page); | |
1573 | } | |
68bdc8d6 HD |
1574 | |
1575 | /* | |
1576 | * It is conceivable that a racing task removed this page from | |
1577 | * swap cache just before we acquired the page lock at the top, | |
1578 | * or while we dropped it in unuse_mm(). The page might even | |
1579 | * be back in swap cache on another swap area: that we must not | |
1580 | * delete, since it may not have been written out to swap yet. | |
1581 | */ | |
1582 | if (PageSwapCache(page) && | |
1583 | likely(page_private(page) == entry.val)) | |
2e0e26c7 | 1584 | delete_from_swap_cache(page); |
1da177e4 LT |
1585 | |
1586 | /* | |
1587 | * So we could skip searching mms once swap count went | |
1588 | * to 1, we did not mark any present ptes as dirty: must | |
2706a1b8 | 1589 | * mark page dirty so shrink_page_list will preserve it. |
1da177e4 LT |
1590 | */ |
1591 | SetPageDirty(page); | |
1592 | unlock_page(page); | |
09cbfeaf | 1593 | put_page(page); |
1da177e4 LT |
1594 | |
1595 | /* | |
1596 | * Make sure that we aren't completely killing | |
1597 | * interactive performance. | |
1598 | */ | |
1599 | cond_resched(); | |
38b5faf4 DM |
1600 | if (frontswap && pages_to_unuse > 0) { |
1601 | if (!--pages_to_unuse) | |
1602 | break; | |
1603 | } | |
1da177e4 LT |
1604 | } |
1605 | ||
1606 | mmput(start_mm); | |
1da177e4 LT |
1607 | return retval; |
1608 | } | |
1609 | ||
1610 | /* | |
5d337b91 HD |
1611 | * After a successful try_to_unuse, if no swap is now in use, we know |
1612 | * we can empty the mmlist. swap_lock must be held on entry and exit. | |
1613 | * Note that mmlist_lock nests inside swap_lock, and an mm must be | |
1da177e4 LT |
1614 | * added to the mmlist just after page_duplicate - before would be racy. |
1615 | */ | |
1616 | static void drain_mmlist(void) | |
1617 | { | |
1618 | struct list_head *p, *next; | |
efa90a98 | 1619 | unsigned int type; |
1da177e4 | 1620 | |
efa90a98 HD |
1621 | for (type = 0; type < nr_swapfiles; type++) |
1622 | if (swap_info[type]->inuse_pages) | |
1da177e4 LT |
1623 | return; |
1624 | spin_lock(&mmlist_lock); | |
1625 | list_for_each_safe(p, next, &init_mm.mmlist) | |
1626 | list_del_init(p); | |
1627 | spin_unlock(&mmlist_lock); | |
1628 | } | |
1629 | ||
1630 | /* | |
1631 | * Use this swapdev's extent info to locate the (PAGE_SIZE) block which | |
d4906e1a LS |
1632 | * corresponds to page offset for the specified swap entry. |
1633 | * Note that the type of this function is sector_t, but it returns page offset | |
1634 | * into the bdev, not sector offset. | |
1da177e4 | 1635 | */ |
d4906e1a | 1636 | static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev) |
1da177e4 | 1637 | { |
f29ad6a9 HD |
1638 | struct swap_info_struct *sis; |
1639 | struct swap_extent *start_se; | |
1640 | struct swap_extent *se; | |
1641 | pgoff_t offset; | |
1642 | ||
efa90a98 | 1643 | sis = swap_info[swp_type(entry)]; |
f29ad6a9 HD |
1644 | *bdev = sis->bdev; |
1645 | ||
1646 | offset = swp_offset(entry); | |
1647 | start_se = sis->curr_swap_extent; | |
1648 | se = start_se; | |
1da177e4 LT |
1649 | |
1650 | for ( ; ; ) { | |
1da177e4 LT |
1651 | if (se->start_page <= offset && |
1652 | offset < (se->start_page + se->nr_pages)) { | |
1653 | return se->start_block + (offset - se->start_page); | |
1654 | } | |
a8ae4991 | 1655 | se = list_next_entry(se, list); |
1da177e4 LT |
1656 | sis->curr_swap_extent = se; |
1657 | BUG_ON(se == start_se); /* It *must* be present */ | |
1658 | } | |
1659 | } | |
1660 | ||
d4906e1a LS |
1661 | /* |
1662 | * Returns the page offset into bdev for the specified page's swap entry. | |
1663 | */ | |
1664 | sector_t map_swap_page(struct page *page, struct block_device **bdev) | |
1665 | { | |
1666 | swp_entry_t entry; | |
1667 | entry.val = page_private(page); | |
1668 | return map_swap_entry(entry, bdev); | |
1669 | } | |
1670 | ||
1da177e4 LT |
1671 | /* |
1672 | * Free all of a swapdev's extent information | |
1673 | */ | |
1674 | static void destroy_swap_extents(struct swap_info_struct *sis) | |
1675 | { | |
9625a5f2 | 1676 | while (!list_empty(&sis->first_swap_extent.list)) { |
1da177e4 LT |
1677 | struct swap_extent *se; |
1678 | ||
a8ae4991 | 1679 | se = list_first_entry(&sis->first_swap_extent.list, |
1da177e4 LT |
1680 | struct swap_extent, list); |
1681 | list_del(&se->list); | |
1682 | kfree(se); | |
1683 | } | |
62c230bc MG |
1684 | |
1685 | if (sis->flags & SWP_FILE) { | |
1686 | struct file *swap_file = sis->swap_file; | |
1687 | struct address_space *mapping = swap_file->f_mapping; | |
1688 | ||
1689 | sis->flags &= ~SWP_FILE; | |
1690 | mapping->a_ops->swap_deactivate(swap_file); | |
1691 | } | |
1da177e4 LT |
1692 | } |
1693 | ||
1694 | /* | |
1695 | * Add a block range (and the corresponding page range) into this swapdev's | |
11d31886 | 1696 | * extent list. The extent list is kept sorted in page order. |
1da177e4 | 1697 | * |
11d31886 | 1698 | * This function rather assumes that it is called in ascending page order. |
1da177e4 | 1699 | */ |
a509bc1a | 1700 | int |
1da177e4 LT |
1701 | add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, |
1702 | unsigned long nr_pages, sector_t start_block) | |
1703 | { | |
1704 | struct swap_extent *se; | |
1705 | struct swap_extent *new_se; | |
1706 | struct list_head *lh; | |
1707 | ||
9625a5f2 HD |
1708 | if (start_page == 0) { |
1709 | se = &sis->first_swap_extent; | |
1710 | sis->curr_swap_extent = se; | |
1711 | se->start_page = 0; | |
1712 | se->nr_pages = nr_pages; | |
1713 | se->start_block = start_block; | |
1714 | return 1; | |
1715 | } else { | |
1716 | lh = sis->first_swap_extent.list.prev; /* Highest extent */ | |
1da177e4 | 1717 | se = list_entry(lh, struct swap_extent, list); |
11d31886 HD |
1718 | BUG_ON(se->start_page + se->nr_pages != start_page); |
1719 | if (se->start_block + se->nr_pages == start_block) { | |
1da177e4 LT |
1720 | /* Merge it */ |
1721 | se->nr_pages += nr_pages; | |
1722 | return 0; | |
1723 | } | |
1da177e4 LT |
1724 | } |
1725 | ||
1726 | /* | |
1727 | * No merge. Insert a new extent, preserving ordering. | |
1728 | */ | |
1729 | new_se = kmalloc(sizeof(*se), GFP_KERNEL); | |
1730 | if (new_se == NULL) | |
1731 | return -ENOMEM; | |
1732 | new_se->start_page = start_page; | |
1733 | new_se->nr_pages = nr_pages; | |
1734 | new_se->start_block = start_block; | |
1735 | ||
9625a5f2 | 1736 | list_add_tail(&new_se->list, &sis->first_swap_extent.list); |
53092a74 | 1737 | return 1; |
1da177e4 LT |
1738 | } |
1739 | ||
1740 | /* | |
1741 | * A `swap extent' is a simple thing which maps a contiguous range of pages | |
1742 | * onto a contiguous range of disk blocks. An ordered list of swap extents | |
1743 | * is built at swapon time and is then used at swap_writepage/swap_readpage | |
1744 | * time for locating where on disk a page belongs. | |
1745 | * | |
1746 | * If the swapfile is an S_ISBLK block device, a single extent is installed. | |
1747 | * This is done so that the main operating code can treat S_ISBLK and S_ISREG | |
1748 | * swap files identically. | |
1749 | * | |
1750 | * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap | |
1751 | * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK | |
1752 | * swapfiles are handled *identically* after swapon time. | |
1753 | * | |
1754 | * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks | |
1755 | * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If | |
1756 | * some stray blocks are found which do not fall within the PAGE_SIZE alignment | |
1757 | * requirements, they are simply tossed out - we will never use those blocks | |
1758 | * for swapping. | |
1759 | * | |
b0d9bcd4 | 1760 | * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This |
1da177e4 LT |
1761 | * prevents root from shooting her foot off by ftruncating an in-use swapfile, |
1762 | * which will scribble on the fs. | |
1763 | * | |
1764 | * The amount of disk space which a single swap extent represents varies. | |
1765 | * Typically it is in the 1-4 megabyte range. So we can have hundreds of | |
1766 | * extents in the list. To avoid much list walking, we cache the previous | |
1767 | * search location in `curr_swap_extent', and start new searches from there. | |
1768 | * This is extremely effective. The average number of iterations in | |
1769 | * map_swap_page() has been measured at about 0.3 per page. - akpm. | |
1770 | */ | |
53092a74 | 1771 | static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
1da177e4 | 1772 | { |
62c230bc MG |
1773 | struct file *swap_file = sis->swap_file; |
1774 | struct address_space *mapping = swap_file->f_mapping; | |
1775 | struct inode *inode = mapping->host; | |
1da177e4 LT |
1776 | int ret; |
1777 | ||
1da177e4 LT |
1778 | if (S_ISBLK(inode->i_mode)) { |
1779 | ret = add_swap_extent(sis, 0, sis->max, 0); | |
53092a74 | 1780 | *span = sis->pages; |
a509bc1a | 1781 | return ret; |
1da177e4 LT |
1782 | } |
1783 | ||
62c230bc | 1784 | if (mapping->a_ops->swap_activate) { |
a509bc1a | 1785 | ret = mapping->a_ops->swap_activate(sis, swap_file, span); |
62c230bc MG |
1786 | if (!ret) { |
1787 | sis->flags |= SWP_FILE; | |
1788 | ret = add_swap_extent(sis, 0, sis->max, 0); | |
1789 | *span = sis->pages; | |
1790 | } | |
a509bc1a | 1791 | return ret; |
62c230bc MG |
1792 | } |
1793 | ||
a509bc1a | 1794 | return generic_swapfile_activate(sis, swap_file, span); |
1da177e4 LT |
1795 | } |
1796 | ||
cf0cac0a | 1797 | static void _enable_swap_info(struct swap_info_struct *p, int prio, |
2a8f9449 SL |
1798 | unsigned char *swap_map, |
1799 | struct swap_cluster_info *cluster_info) | |
40531542 | 1800 | { |
40531542 CEB |
1801 | if (prio >= 0) |
1802 | p->prio = prio; | |
1803 | else | |
1804 | p->prio = --least_priority; | |
18ab4d4c DS |
1805 | /* |
1806 | * the plist prio is negated because plist ordering is | |
1807 | * low-to-high, while swap ordering is high-to-low | |
1808 | */ | |
1809 | p->list.prio = -p->prio; | |
1810 | p->avail_list.prio = -p->prio; | |
40531542 | 1811 | p->swap_map = swap_map; |
2a8f9449 | 1812 | p->cluster_info = cluster_info; |
40531542 | 1813 | p->flags |= SWP_WRITEOK; |
ec8acf20 | 1814 | atomic_long_add(p->pages, &nr_swap_pages); |
40531542 CEB |
1815 | total_swap_pages += p->pages; |
1816 | ||
adfab836 | 1817 | assert_spin_locked(&swap_lock); |
adfab836 | 1818 | /* |
18ab4d4c DS |
1819 | * both lists are plists, and thus priority ordered. |
1820 | * swap_active_head needs to be priority ordered for swapoff(), | |
1821 | * which on removal of any swap_info_struct with an auto-assigned | |
1822 | * (i.e. negative) priority increments the auto-assigned priority | |
1823 | * of any lower-priority swap_info_structs. | |
1824 | * swap_avail_head needs to be priority ordered for get_swap_page(), | |
1825 | * which allocates swap pages from the highest available priority | |
1826 | * swap_info_struct. | |
adfab836 | 1827 | */ |
18ab4d4c DS |
1828 | plist_add(&p->list, &swap_active_head); |
1829 | spin_lock(&swap_avail_lock); | |
1830 | plist_add(&p->avail_list, &swap_avail_head); | |
1831 | spin_unlock(&swap_avail_lock); | |
cf0cac0a CEB |
1832 | } |
1833 | ||
1834 | static void enable_swap_info(struct swap_info_struct *p, int prio, | |
1835 | unsigned char *swap_map, | |
2a8f9449 | 1836 | struct swap_cluster_info *cluster_info, |
cf0cac0a CEB |
1837 | unsigned long *frontswap_map) |
1838 | { | |
4f89849d | 1839 | frontswap_init(p->type, frontswap_map); |
cf0cac0a | 1840 | spin_lock(&swap_lock); |
ec8acf20 | 1841 | spin_lock(&p->lock); |
2a8f9449 | 1842 | _enable_swap_info(p, prio, swap_map, cluster_info); |
ec8acf20 | 1843 | spin_unlock(&p->lock); |
cf0cac0a CEB |
1844 | spin_unlock(&swap_lock); |
1845 | } | |
1846 | ||
1847 | static void reinsert_swap_info(struct swap_info_struct *p) | |
1848 | { | |
1849 | spin_lock(&swap_lock); | |
ec8acf20 | 1850 | spin_lock(&p->lock); |
2a8f9449 | 1851 | _enable_swap_info(p, p->prio, p->swap_map, p->cluster_info); |
ec8acf20 | 1852 | spin_unlock(&p->lock); |
40531542 CEB |
1853 | spin_unlock(&swap_lock); |
1854 | } | |
1855 | ||
c4ea37c2 | 1856 | SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) |
1da177e4 | 1857 | { |
73c34b6a | 1858 | struct swap_info_struct *p = NULL; |
8d69aaee | 1859 | unsigned char *swap_map; |
2a8f9449 | 1860 | struct swap_cluster_info *cluster_info; |
4f89849d | 1861 | unsigned long *frontswap_map; |
1da177e4 LT |
1862 | struct file *swap_file, *victim; |
1863 | struct address_space *mapping; | |
1864 | struct inode *inode; | |
91a27b2a | 1865 | struct filename *pathname; |
adfab836 | 1866 | int err, found = 0; |
5b808a23 | 1867 | unsigned int old_block_size; |
886bb7e9 | 1868 | |
1da177e4 LT |
1869 | if (!capable(CAP_SYS_ADMIN)) |
1870 | return -EPERM; | |
1871 | ||
191c5424 AV |
1872 | BUG_ON(!current->mm); |
1873 | ||
1da177e4 | 1874 | pathname = getname(specialfile); |
1da177e4 | 1875 | if (IS_ERR(pathname)) |
f58b59c1 | 1876 | return PTR_ERR(pathname); |
1da177e4 | 1877 | |
669abf4e | 1878 | victim = file_open_name(pathname, O_RDWR|O_LARGEFILE, 0); |
1da177e4 LT |
1879 | err = PTR_ERR(victim); |
1880 | if (IS_ERR(victim)) | |
1881 | goto out; | |
1882 | ||
1883 | mapping = victim->f_mapping; | |
5d337b91 | 1884 | spin_lock(&swap_lock); |
18ab4d4c | 1885 | plist_for_each_entry(p, &swap_active_head, list) { |
22c6f8fd | 1886 | if (p->flags & SWP_WRITEOK) { |
adfab836 DS |
1887 | if (p->swap_file->f_mapping == mapping) { |
1888 | found = 1; | |
1da177e4 | 1889 | break; |
adfab836 | 1890 | } |
1da177e4 | 1891 | } |
1da177e4 | 1892 | } |
adfab836 | 1893 | if (!found) { |
1da177e4 | 1894 | err = -EINVAL; |
5d337b91 | 1895 | spin_unlock(&swap_lock); |
1da177e4 LT |
1896 | goto out_dput; |
1897 | } | |
191c5424 | 1898 | if (!security_vm_enough_memory_mm(current->mm, p->pages)) |
1da177e4 LT |
1899 | vm_unacct_memory(p->pages); |
1900 | else { | |
1901 | err = -ENOMEM; | |
5d337b91 | 1902 | spin_unlock(&swap_lock); |
1da177e4 LT |
1903 | goto out_dput; |
1904 | } | |
18ab4d4c DS |
1905 | spin_lock(&swap_avail_lock); |
1906 | plist_del(&p->avail_list, &swap_avail_head); | |
1907 | spin_unlock(&swap_avail_lock); | |
ec8acf20 | 1908 | spin_lock(&p->lock); |
78ecba08 | 1909 | if (p->prio < 0) { |
adfab836 DS |
1910 | struct swap_info_struct *si = p; |
1911 | ||
18ab4d4c | 1912 | plist_for_each_entry_continue(si, &swap_active_head, list) { |
adfab836 | 1913 | si->prio++; |
18ab4d4c DS |
1914 | si->list.prio--; |
1915 | si->avail_list.prio--; | |
adfab836 | 1916 | } |
78ecba08 HD |
1917 | least_priority++; |
1918 | } | |
18ab4d4c | 1919 | plist_del(&p->list, &swap_active_head); |
ec8acf20 | 1920 | atomic_long_sub(p->pages, &nr_swap_pages); |
1da177e4 LT |
1921 | total_swap_pages -= p->pages; |
1922 | p->flags &= ~SWP_WRITEOK; | |
ec8acf20 | 1923 | spin_unlock(&p->lock); |
5d337b91 | 1924 | spin_unlock(&swap_lock); |
fb4f88dc | 1925 | |
e1e12d2f | 1926 | set_current_oom_origin(); |
adfab836 | 1927 | err = try_to_unuse(p->type, false, 0); /* force unuse all pages */ |
e1e12d2f | 1928 | clear_current_oom_origin(); |
1da177e4 | 1929 | |
1da177e4 LT |
1930 | if (err) { |
1931 | /* re-insert swap space back into swap_list */ | |
cf0cac0a | 1932 | reinsert_swap_info(p); |
1da177e4 LT |
1933 | goto out_dput; |
1934 | } | |
52b7efdb | 1935 | |
815c2c54 SL |
1936 | flush_work(&p->discard_work); |
1937 | ||
5d337b91 | 1938 | destroy_swap_extents(p); |
570a335b HD |
1939 | if (p->flags & SWP_CONTINUED) |
1940 | free_swap_count_continuations(p); | |
1941 | ||
fc0abb14 | 1942 | mutex_lock(&swapon_mutex); |
5d337b91 | 1943 | spin_lock(&swap_lock); |
ec8acf20 | 1944 | spin_lock(&p->lock); |
5d337b91 HD |
1945 | drain_mmlist(); |
1946 | ||
52b7efdb | 1947 | /* wait for anyone still in scan_swap_map */ |
52b7efdb HD |
1948 | p->highest_bit = 0; /* cuts scans short */ |
1949 | while (p->flags >= SWP_SCANNING) { | |
ec8acf20 | 1950 | spin_unlock(&p->lock); |
5d337b91 | 1951 | spin_unlock(&swap_lock); |
13e4b57f | 1952 | schedule_timeout_uninterruptible(1); |
5d337b91 | 1953 | spin_lock(&swap_lock); |
ec8acf20 | 1954 | spin_lock(&p->lock); |
52b7efdb | 1955 | } |
52b7efdb | 1956 | |
1da177e4 | 1957 | swap_file = p->swap_file; |
5b808a23 | 1958 | old_block_size = p->old_block_size; |
1da177e4 LT |
1959 | p->swap_file = NULL; |
1960 | p->max = 0; | |
1961 | swap_map = p->swap_map; | |
1962 | p->swap_map = NULL; | |
2a8f9449 SL |
1963 | cluster_info = p->cluster_info; |
1964 | p->cluster_info = NULL; | |
4f89849d | 1965 | frontswap_map = frontswap_map_get(p); |
ec8acf20 | 1966 | spin_unlock(&p->lock); |
5d337b91 | 1967 | spin_unlock(&swap_lock); |
adfab836 | 1968 | frontswap_invalidate_area(p->type); |
58e97ba6 | 1969 | frontswap_map_set(p, NULL); |
fc0abb14 | 1970 | mutex_unlock(&swapon_mutex); |
ebc2a1a6 SL |
1971 | free_percpu(p->percpu_cluster); |
1972 | p->percpu_cluster = NULL; | |
1da177e4 | 1973 | vfree(swap_map); |
2a8f9449 | 1974 | vfree(cluster_info); |
4f89849d | 1975 | vfree(frontswap_map); |
2de1a7e4 | 1976 | /* Destroy swap account information */ |
adfab836 | 1977 | swap_cgroup_swapoff(p->type); |
27a7faa0 | 1978 | |
1da177e4 LT |
1979 | inode = mapping->host; |
1980 | if (S_ISBLK(inode->i_mode)) { | |
1981 | struct block_device *bdev = I_BDEV(inode); | |
5b808a23 | 1982 | set_blocksize(bdev, old_block_size); |
e525fd89 | 1983 | blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); |
1da177e4 | 1984 | } else { |
5955102c | 1985 | inode_lock(inode); |
1da177e4 | 1986 | inode->i_flags &= ~S_SWAPFILE; |
5955102c | 1987 | inode_unlock(inode); |
1da177e4 LT |
1988 | } |
1989 | filp_close(swap_file, NULL); | |
f893ab41 WY |
1990 | |
1991 | /* | |
1992 | * Clear the SWP_USED flag after all resources are freed so that swapon | |
1993 | * can reuse this swap_info in alloc_swap_info() safely. It is ok to | |
1994 | * not hold p->lock after we cleared its SWP_WRITEOK. | |
1995 | */ | |
1996 | spin_lock(&swap_lock); | |
1997 | p->flags = 0; | |
1998 | spin_unlock(&swap_lock); | |
1999 | ||
1da177e4 | 2000 | err = 0; |
66d7dd51 KS |
2001 | atomic_inc(&proc_poll_event); |
2002 | wake_up_interruptible(&proc_poll_wait); | |
1da177e4 LT |
2003 | |
2004 | out_dput: | |
2005 | filp_close(victim, NULL); | |
2006 | out: | |
f58b59c1 | 2007 | putname(pathname); |
1da177e4 LT |
2008 | return err; |
2009 | } | |
2010 | ||
2011 | #ifdef CONFIG_PROC_FS | |
66d7dd51 KS |
2012 | static unsigned swaps_poll(struct file *file, poll_table *wait) |
2013 | { | |
f1514638 | 2014 | struct seq_file *seq = file->private_data; |
66d7dd51 KS |
2015 | |
2016 | poll_wait(file, &proc_poll_wait, wait); | |
2017 | ||
f1514638 KS |
2018 | if (seq->poll_event != atomic_read(&proc_poll_event)) { |
2019 | seq->poll_event = atomic_read(&proc_poll_event); | |
66d7dd51 KS |
2020 | return POLLIN | POLLRDNORM | POLLERR | POLLPRI; |
2021 | } | |
2022 | ||
2023 | return POLLIN | POLLRDNORM; | |
2024 | } | |
2025 | ||
1da177e4 LT |
2026 | /* iterator */ |
2027 | static void *swap_start(struct seq_file *swap, loff_t *pos) | |
2028 | { | |
efa90a98 HD |
2029 | struct swap_info_struct *si; |
2030 | int type; | |
1da177e4 LT |
2031 | loff_t l = *pos; |
2032 | ||
fc0abb14 | 2033 | mutex_lock(&swapon_mutex); |
1da177e4 | 2034 | |
881e4aab SS |
2035 | if (!l) |
2036 | return SEQ_START_TOKEN; | |
2037 | ||
efa90a98 HD |
2038 | for (type = 0; type < nr_swapfiles; type++) { |
2039 | smp_rmb(); /* read nr_swapfiles before swap_info[type] */ | |
2040 | si = swap_info[type]; | |
2041 | if (!(si->flags & SWP_USED) || !si->swap_map) | |
1da177e4 | 2042 | continue; |
881e4aab | 2043 | if (!--l) |
efa90a98 | 2044 | return si; |
1da177e4 LT |
2045 | } |
2046 | ||
2047 | return NULL; | |
2048 | } | |
2049 | ||
2050 | static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) | |
2051 | { | |
efa90a98 HD |
2052 | struct swap_info_struct *si = v; |
2053 | int type; | |
1da177e4 | 2054 | |
881e4aab | 2055 | if (v == SEQ_START_TOKEN) |
efa90a98 HD |
2056 | type = 0; |
2057 | else | |
2058 | type = si->type + 1; | |
881e4aab | 2059 | |
efa90a98 HD |
2060 | for (; type < nr_swapfiles; type++) { |
2061 | smp_rmb(); /* read nr_swapfiles before swap_info[type] */ | |
2062 | si = swap_info[type]; | |
2063 | if (!(si->flags & SWP_USED) || !si->swap_map) | |
1da177e4 LT |
2064 | continue; |
2065 | ++*pos; | |
efa90a98 | 2066 | return si; |
1da177e4 LT |
2067 | } |
2068 | ||
2069 | return NULL; | |
2070 | } | |
2071 | ||
2072 | static void swap_stop(struct seq_file *swap, void *v) | |
2073 | { | |
fc0abb14 | 2074 | mutex_unlock(&swapon_mutex); |
1da177e4 LT |
2075 | } |
2076 | ||
2077 | static int swap_show(struct seq_file *swap, void *v) | |
2078 | { | |
efa90a98 | 2079 | struct swap_info_struct *si = v; |
1da177e4 LT |
2080 | struct file *file; |
2081 | int len; | |
2082 | ||
efa90a98 | 2083 | if (si == SEQ_START_TOKEN) { |
881e4aab SS |
2084 | seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n"); |
2085 | return 0; | |
2086 | } | |
1da177e4 | 2087 | |
efa90a98 | 2088 | file = si->swap_file; |
2726d566 | 2089 | len = seq_file_path(swap, file, " \t\n\\"); |
6eb396dc | 2090 | seq_printf(swap, "%*s%s\t%u\t%u\t%d\n", |
886bb7e9 | 2091 | len < 40 ? 40 - len : 1, " ", |
496ad9aa | 2092 | S_ISBLK(file_inode(file)->i_mode) ? |
1da177e4 | 2093 | "partition" : "file\t", |
efa90a98 HD |
2094 | si->pages << (PAGE_SHIFT - 10), |
2095 | si->inuse_pages << (PAGE_SHIFT - 10), | |
2096 | si->prio); | |
1da177e4 LT |
2097 | return 0; |
2098 | } | |
2099 | ||
15ad7cdc | 2100 | static const struct seq_operations swaps_op = { |
1da177e4 LT |
2101 | .start = swap_start, |
2102 | .next = swap_next, | |
2103 | .stop = swap_stop, | |
2104 | .show = swap_show | |
2105 | }; | |
2106 | ||
2107 | static int swaps_open(struct inode *inode, struct file *file) | |
2108 | { | |
f1514638 | 2109 | struct seq_file *seq; |
66d7dd51 KS |
2110 | int ret; |
2111 | ||
66d7dd51 | 2112 | ret = seq_open(file, &swaps_op); |
f1514638 | 2113 | if (ret) |
66d7dd51 | 2114 | return ret; |
66d7dd51 | 2115 | |
f1514638 KS |
2116 | seq = file->private_data; |
2117 | seq->poll_event = atomic_read(&proc_poll_event); | |
2118 | return 0; | |
1da177e4 LT |
2119 | } |
2120 | ||
15ad7cdc | 2121 | static const struct file_operations proc_swaps_operations = { |
1da177e4 LT |
2122 | .open = swaps_open, |
2123 | .read = seq_read, | |
2124 | .llseek = seq_lseek, | |
2125 | .release = seq_release, | |
66d7dd51 | 2126 | .poll = swaps_poll, |
1da177e4 LT |
2127 | }; |
2128 | ||
2129 | static int __init procswaps_init(void) | |
2130 | { | |
3d71f86f | 2131 | proc_create("swaps", 0, NULL, &proc_swaps_operations); |
1da177e4 LT |
2132 | return 0; |
2133 | } | |
2134 | __initcall(procswaps_init); | |
2135 | #endif /* CONFIG_PROC_FS */ | |
2136 | ||
1796316a JB |
2137 | #ifdef MAX_SWAPFILES_CHECK |
2138 | static int __init max_swapfiles_check(void) | |
2139 | { | |
2140 | MAX_SWAPFILES_CHECK(); | |
2141 | return 0; | |
2142 | } | |
2143 | late_initcall(max_swapfiles_check); | |
2144 | #endif | |
2145 | ||
53cbb243 | 2146 | static struct swap_info_struct *alloc_swap_info(void) |
1da177e4 | 2147 | { |
73c34b6a | 2148 | struct swap_info_struct *p; |
1da177e4 | 2149 | unsigned int type; |
efa90a98 HD |
2150 | |
2151 | p = kzalloc(sizeof(*p), GFP_KERNEL); | |
2152 | if (!p) | |
53cbb243 | 2153 | return ERR_PTR(-ENOMEM); |
efa90a98 | 2154 | |
5d337b91 | 2155 | spin_lock(&swap_lock); |
efa90a98 HD |
2156 | for (type = 0; type < nr_swapfiles; type++) { |
2157 | if (!(swap_info[type]->flags & SWP_USED)) | |
1da177e4 | 2158 | break; |
efa90a98 | 2159 | } |
0697212a | 2160 | if (type >= MAX_SWAPFILES) { |
5d337b91 | 2161 | spin_unlock(&swap_lock); |
efa90a98 | 2162 | kfree(p); |
730c0581 | 2163 | return ERR_PTR(-EPERM); |
1da177e4 | 2164 | } |
efa90a98 HD |
2165 | if (type >= nr_swapfiles) { |
2166 | p->type = type; | |
2167 | swap_info[type] = p; | |
2168 | /* | |
2169 | * Write swap_info[type] before nr_swapfiles, in case a | |
2170 | * racing procfs swap_start() or swap_next() is reading them. | |
2171 | * (We never shrink nr_swapfiles, we never free this entry.) | |
2172 | */ | |
2173 | smp_wmb(); | |
2174 | nr_swapfiles++; | |
2175 | } else { | |
2176 | kfree(p); | |
2177 | p = swap_info[type]; | |
2178 | /* | |
2179 | * Do not memset this entry: a racing procfs swap_next() | |
2180 | * would be relying on p->type to remain valid. | |
2181 | */ | |
2182 | } | |
9625a5f2 | 2183 | INIT_LIST_HEAD(&p->first_swap_extent.list); |
18ab4d4c DS |
2184 | plist_node_init(&p->list, 0); |
2185 | plist_node_init(&p->avail_list, 0); | |
1da177e4 | 2186 | p->flags = SWP_USED; |
5d337b91 | 2187 | spin_unlock(&swap_lock); |
ec8acf20 | 2188 | spin_lock_init(&p->lock); |
efa90a98 | 2189 | |
53cbb243 | 2190 | return p; |
53cbb243 CEB |
2191 | } |
2192 | ||
4d0e1e10 CEB |
2193 | static int claim_swapfile(struct swap_info_struct *p, struct inode *inode) |
2194 | { | |
2195 | int error; | |
2196 | ||
2197 | if (S_ISBLK(inode->i_mode)) { | |
2198 | p->bdev = bdgrab(I_BDEV(inode)); | |
2199 | error = blkdev_get(p->bdev, | |
6f179af8 | 2200 | FMODE_READ | FMODE_WRITE | FMODE_EXCL, p); |
4d0e1e10 CEB |
2201 | if (error < 0) { |
2202 | p->bdev = NULL; | |
6f179af8 | 2203 | return error; |
4d0e1e10 CEB |
2204 | } |
2205 | p->old_block_size = block_size(p->bdev); | |
2206 | error = set_blocksize(p->bdev, PAGE_SIZE); | |
2207 | if (error < 0) | |
87ade72a | 2208 | return error; |
4d0e1e10 CEB |
2209 | p->flags |= SWP_BLKDEV; |
2210 | } else if (S_ISREG(inode->i_mode)) { | |
2211 | p->bdev = inode->i_sb->s_bdev; | |
5955102c | 2212 | inode_lock(inode); |
87ade72a CEB |
2213 | if (IS_SWAPFILE(inode)) |
2214 | return -EBUSY; | |
2215 | } else | |
2216 | return -EINVAL; | |
4d0e1e10 CEB |
2217 | |
2218 | return 0; | |
4d0e1e10 CEB |
2219 | } |
2220 | ||
ca8bd38b CEB |
2221 | static unsigned long read_swap_header(struct swap_info_struct *p, |
2222 | union swap_header *swap_header, | |
2223 | struct inode *inode) | |
2224 | { | |
2225 | int i; | |
2226 | unsigned long maxpages; | |
2227 | unsigned long swapfilepages; | |
d6bbbd29 | 2228 | unsigned long last_page; |
ca8bd38b CEB |
2229 | |
2230 | if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) { | |
465c47fd | 2231 | pr_err("Unable to find swap-space signature\n"); |
38719025 | 2232 | return 0; |
ca8bd38b CEB |
2233 | } |
2234 | ||
2235 | /* swap partition endianess hack... */ | |
2236 | if (swab32(swap_header->info.version) == 1) { | |
2237 | swab32s(&swap_header->info.version); | |
2238 | swab32s(&swap_header->info.last_page); | |
2239 | swab32s(&swap_header->info.nr_badpages); | |
dd111be6 JH |
2240 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
2241 | return 0; | |
ca8bd38b CEB |
2242 | for (i = 0; i < swap_header->info.nr_badpages; i++) |
2243 | swab32s(&swap_header->info.badpages[i]); | |
2244 | } | |
2245 | /* Check the swap header's sub-version */ | |
2246 | if (swap_header->info.version != 1) { | |
465c47fd AM |
2247 | pr_warn("Unable to handle swap header version %d\n", |
2248 | swap_header->info.version); | |
38719025 | 2249 | return 0; |
ca8bd38b CEB |
2250 | } |
2251 | ||
2252 | p->lowest_bit = 1; | |
2253 | p->cluster_next = 1; | |
2254 | p->cluster_nr = 0; | |
2255 | ||
2256 | /* | |
2257 | * Find out how many pages are allowed for a single swap | |
9b15b817 | 2258 | * device. There are two limiting factors: 1) the number |
a2c16d6c HD |
2259 | * of bits for the swap offset in the swp_entry_t type, and |
2260 | * 2) the number of bits in the swap pte as defined by the | |
9b15b817 | 2261 | * different architectures. In order to find the |
a2c16d6c | 2262 | * largest possible bit mask, a swap entry with swap type 0 |
ca8bd38b | 2263 | * and swap offset ~0UL is created, encoded to a swap pte, |
a2c16d6c | 2264 | * decoded to a swp_entry_t again, and finally the swap |
ca8bd38b CEB |
2265 | * offset is extracted. This will mask all the bits from |
2266 | * the initial ~0UL mask that can't be encoded in either | |
2267 | * the swp_entry_t or the architecture definition of a | |
9b15b817 | 2268 | * swap pte. |
ca8bd38b CEB |
2269 | */ |
2270 | maxpages = swp_offset(pte_to_swp_entry( | |
9b15b817 | 2271 | swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1; |
d6bbbd29 RJ |
2272 | last_page = swap_header->info.last_page; |
2273 | if (last_page > maxpages) { | |
465c47fd | 2274 | pr_warn("Truncating oversized swap area, only using %luk out of %luk\n", |
d6bbbd29 RJ |
2275 | maxpages << (PAGE_SHIFT - 10), |
2276 | last_page << (PAGE_SHIFT - 10)); | |
2277 | } | |
2278 | if (maxpages > last_page) { | |
2279 | maxpages = last_page + 1; | |
ca8bd38b CEB |
2280 | /* p->max is an unsigned int: don't overflow it */ |
2281 | if ((unsigned int)maxpages == 0) | |
2282 | maxpages = UINT_MAX; | |
2283 | } | |
2284 | p->highest_bit = maxpages - 1; | |
2285 | ||
2286 | if (!maxpages) | |
38719025 | 2287 | return 0; |
ca8bd38b CEB |
2288 | swapfilepages = i_size_read(inode) >> PAGE_SHIFT; |
2289 | if (swapfilepages && maxpages > swapfilepages) { | |
465c47fd | 2290 | pr_warn("Swap area shorter than signature indicates\n"); |
38719025 | 2291 | return 0; |
ca8bd38b CEB |
2292 | } |
2293 | if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) | |
38719025 | 2294 | return 0; |
ca8bd38b | 2295 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
38719025 | 2296 | return 0; |
ca8bd38b CEB |
2297 | |
2298 | return maxpages; | |
ca8bd38b CEB |
2299 | } |
2300 | ||
915d4d7b CEB |
2301 | static int setup_swap_map_and_extents(struct swap_info_struct *p, |
2302 | union swap_header *swap_header, | |
2303 | unsigned char *swap_map, | |
2a8f9449 | 2304 | struct swap_cluster_info *cluster_info, |
915d4d7b CEB |
2305 | unsigned long maxpages, |
2306 | sector_t *span) | |
2307 | { | |
2308 | int i; | |
915d4d7b CEB |
2309 | unsigned int nr_good_pages; |
2310 | int nr_extents; | |
2a8f9449 SL |
2311 | unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); |
2312 | unsigned long idx = p->cluster_next / SWAPFILE_CLUSTER; | |
915d4d7b CEB |
2313 | |
2314 | nr_good_pages = maxpages - 1; /* omit header page */ | |
2315 | ||
6b534915 HY |
2316 | cluster_list_init(&p->free_clusters); |
2317 | cluster_list_init(&p->discard_clusters); | |
2a8f9449 | 2318 | |
915d4d7b CEB |
2319 | for (i = 0; i < swap_header->info.nr_badpages; i++) { |
2320 | unsigned int page_nr = swap_header->info.badpages[i]; | |
bdb8e3f6 CEB |
2321 | if (page_nr == 0 || page_nr > swap_header->info.last_page) |
2322 | return -EINVAL; | |
915d4d7b CEB |
2323 | if (page_nr < maxpages) { |
2324 | swap_map[page_nr] = SWAP_MAP_BAD; | |
2325 | nr_good_pages--; | |
2a8f9449 SL |
2326 | /* |
2327 | * Haven't marked the cluster free yet, no list | |
2328 | * operation involved | |
2329 | */ | |
2330 | inc_cluster_info_page(p, cluster_info, page_nr); | |
915d4d7b CEB |
2331 | } |
2332 | } | |
2333 | ||
2a8f9449 SL |
2334 | /* Haven't marked the cluster free yet, no list operation involved */ |
2335 | for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++) | |
2336 | inc_cluster_info_page(p, cluster_info, i); | |
2337 | ||
915d4d7b CEB |
2338 | if (nr_good_pages) { |
2339 | swap_map[0] = SWAP_MAP_BAD; | |
2a8f9449 SL |
2340 | /* |
2341 | * Not mark the cluster free yet, no list | |
2342 | * operation involved | |
2343 | */ | |
2344 | inc_cluster_info_page(p, cluster_info, 0); | |
915d4d7b CEB |
2345 | p->max = maxpages; |
2346 | p->pages = nr_good_pages; | |
2347 | nr_extents = setup_swap_extents(p, span); | |
bdb8e3f6 CEB |
2348 | if (nr_extents < 0) |
2349 | return nr_extents; | |
915d4d7b CEB |
2350 | nr_good_pages = p->pages; |
2351 | } | |
2352 | if (!nr_good_pages) { | |
465c47fd | 2353 | pr_warn("Empty swap-file\n"); |
bdb8e3f6 | 2354 | return -EINVAL; |
915d4d7b CEB |
2355 | } |
2356 | ||
2a8f9449 SL |
2357 | if (!cluster_info) |
2358 | return nr_extents; | |
2359 | ||
2360 | for (i = 0; i < nr_clusters; i++) { | |
2361 | if (!cluster_count(&cluster_info[idx])) { | |
2362 | cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE); | |
6b534915 HY |
2363 | cluster_list_add_tail(&p->free_clusters, cluster_info, |
2364 | idx); | |
2a8f9449 SL |
2365 | } |
2366 | idx++; | |
2367 | if (idx == nr_clusters) | |
2368 | idx = 0; | |
2369 | } | |
915d4d7b | 2370 | return nr_extents; |
915d4d7b CEB |
2371 | } |
2372 | ||
dcf6b7dd RA |
2373 | /* |
2374 | * Helper to sys_swapon determining if a given swap | |
2375 | * backing device queue supports DISCARD operations. | |
2376 | */ | |
2377 | static bool swap_discardable(struct swap_info_struct *si) | |
2378 | { | |
2379 | struct request_queue *q = bdev_get_queue(si->bdev); | |
2380 | ||
2381 | if (!q || !blk_queue_discard(q)) | |
2382 | return false; | |
2383 | ||
2384 | return true; | |
2385 | } | |
2386 | ||
53cbb243 CEB |
2387 | SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) |
2388 | { | |
2389 | struct swap_info_struct *p; | |
91a27b2a | 2390 | struct filename *name; |
53cbb243 CEB |
2391 | struct file *swap_file = NULL; |
2392 | struct address_space *mapping; | |
40531542 | 2393 | int prio; |
53cbb243 CEB |
2394 | int error; |
2395 | union swap_header *swap_header; | |
915d4d7b | 2396 | int nr_extents; |
53cbb243 CEB |
2397 | sector_t span; |
2398 | unsigned long maxpages; | |
53cbb243 | 2399 | unsigned char *swap_map = NULL; |
2a8f9449 | 2400 | struct swap_cluster_info *cluster_info = NULL; |
38b5faf4 | 2401 | unsigned long *frontswap_map = NULL; |
53cbb243 CEB |
2402 | struct page *page = NULL; |
2403 | struct inode *inode = NULL; | |
53cbb243 | 2404 | |
d15cab97 HD |
2405 | if (swap_flags & ~SWAP_FLAGS_VALID) |
2406 | return -EINVAL; | |
2407 | ||
53cbb243 CEB |
2408 | if (!capable(CAP_SYS_ADMIN)) |
2409 | return -EPERM; | |
2410 | ||
2411 | p = alloc_swap_info(); | |
2542e513 CEB |
2412 | if (IS_ERR(p)) |
2413 | return PTR_ERR(p); | |
53cbb243 | 2414 | |
815c2c54 SL |
2415 | INIT_WORK(&p->discard_work, swap_discard_work); |
2416 | ||
1da177e4 | 2417 | name = getname(specialfile); |
1da177e4 | 2418 | if (IS_ERR(name)) { |
7de7fb6b | 2419 | error = PTR_ERR(name); |
1da177e4 | 2420 | name = NULL; |
bd69010b | 2421 | goto bad_swap; |
1da177e4 | 2422 | } |
669abf4e | 2423 | swap_file = file_open_name(name, O_RDWR|O_LARGEFILE, 0); |
1da177e4 | 2424 | if (IS_ERR(swap_file)) { |
7de7fb6b | 2425 | error = PTR_ERR(swap_file); |
1da177e4 | 2426 | swap_file = NULL; |
bd69010b | 2427 | goto bad_swap; |
1da177e4 LT |
2428 | } |
2429 | ||
2430 | p->swap_file = swap_file; | |
2431 | mapping = swap_file->f_mapping; | |
2130781e | 2432 | inode = mapping->host; |
6f179af8 | 2433 | |
5955102c | 2434 | /* If S_ISREG(inode->i_mode) will do inode_lock(inode); */ |
4d0e1e10 CEB |
2435 | error = claim_swapfile(p, inode); |
2436 | if (unlikely(error)) | |
1da177e4 | 2437 | goto bad_swap; |
1da177e4 | 2438 | |
1da177e4 LT |
2439 | /* |
2440 | * Read the swap header. | |
2441 | */ | |
2442 | if (!mapping->a_ops->readpage) { | |
2443 | error = -EINVAL; | |
2444 | goto bad_swap; | |
2445 | } | |
090d2b18 | 2446 | page = read_mapping_page(mapping, 0, swap_file); |
1da177e4 LT |
2447 | if (IS_ERR(page)) { |
2448 | error = PTR_ERR(page); | |
2449 | goto bad_swap; | |
2450 | } | |
81e33971 | 2451 | swap_header = kmap(page); |
1da177e4 | 2452 | |
ca8bd38b CEB |
2453 | maxpages = read_swap_header(p, swap_header, inode); |
2454 | if (unlikely(!maxpages)) { | |
1da177e4 LT |
2455 | error = -EINVAL; |
2456 | goto bad_swap; | |
2457 | } | |
886bb7e9 | 2458 | |
81e33971 | 2459 | /* OK, set up the swap map and apply the bad block list */ |
803d0c83 | 2460 | swap_map = vzalloc(maxpages); |
81e33971 HD |
2461 | if (!swap_map) { |
2462 | error = -ENOMEM; | |
2463 | goto bad_swap; | |
2464 | } | |
f0571429 MK |
2465 | |
2466 | if (bdi_cap_stable_pages_required(inode_to_bdi(inode))) | |
2467 | p->flags |= SWP_STABLE_WRITES; | |
2468 | ||
2a8f9449 | 2469 | if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) { |
6f179af8 HD |
2470 | int cpu; |
2471 | ||
2a8f9449 SL |
2472 | p->flags |= SWP_SOLIDSTATE; |
2473 | /* | |
2474 | * select a random position to start with to help wear leveling | |
2475 | * SSD | |
2476 | */ | |
2477 | p->cluster_next = 1 + (prandom_u32() % p->highest_bit); | |
2478 | ||
2479 | cluster_info = vzalloc(DIV_ROUND_UP(maxpages, | |
2480 | SWAPFILE_CLUSTER) * sizeof(*cluster_info)); | |
2481 | if (!cluster_info) { | |
2482 | error = -ENOMEM; | |
2483 | goto bad_swap; | |
2484 | } | |
ebc2a1a6 SL |
2485 | p->percpu_cluster = alloc_percpu(struct percpu_cluster); |
2486 | if (!p->percpu_cluster) { | |
2487 | error = -ENOMEM; | |
2488 | goto bad_swap; | |
2489 | } | |
6f179af8 | 2490 | for_each_possible_cpu(cpu) { |
ebc2a1a6 | 2491 | struct percpu_cluster *cluster; |
6f179af8 | 2492 | cluster = per_cpu_ptr(p->percpu_cluster, cpu); |
ebc2a1a6 SL |
2493 | cluster_set_null(&cluster->index); |
2494 | } | |
2a8f9449 | 2495 | } |
1da177e4 | 2496 | |
1421ef3c CEB |
2497 | error = swap_cgroup_swapon(p->type, maxpages); |
2498 | if (error) | |
2499 | goto bad_swap; | |
2500 | ||
915d4d7b | 2501 | nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map, |
2a8f9449 | 2502 | cluster_info, maxpages, &span); |
915d4d7b CEB |
2503 | if (unlikely(nr_extents < 0)) { |
2504 | error = nr_extents; | |
1da177e4 LT |
2505 | goto bad_swap; |
2506 | } | |
38b5faf4 | 2507 | /* frontswap enabled? set up bit-per-page map for frontswap */ |
8ea1d2a1 | 2508 | if (IS_ENABLED(CONFIG_FRONTSWAP)) |
7b57976d | 2509 | frontswap_map = vzalloc(BITS_TO_LONGS(maxpages) * sizeof(long)); |
1da177e4 | 2510 | |
2a8f9449 SL |
2511 | if (p->bdev &&(swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) { |
2512 | /* | |
2513 | * When discard is enabled for swap with no particular | |
2514 | * policy flagged, we set all swap discard flags here in | |
2515 | * order to sustain backward compatibility with older | |
2516 | * swapon(8) releases. | |
2517 | */ | |
2518 | p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD | | |
2519 | SWP_PAGE_DISCARD); | |
dcf6b7dd | 2520 | |
2a8f9449 SL |
2521 | /* |
2522 | * By flagging sys_swapon, a sysadmin can tell us to | |
2523 | * either do single-time area discards only, or to just | |
2524 | * perform discards for released swap page-clusters. | |
2525 | * Now it's time to adjust the p->flags accordingly. | |
2526 | */ | |
2527 | if (swap_flags & SWAP_FLAG_DISCARD_ONCE) | |
2528 | p->flags &= ~SWP_PAGE_DISCARD; | |
2529 | else if (swap_flags & SWAP_FLAG_DISCARD_PAGES) | |
2530 | p->flags &= ~SWP_AREA_DISCARD; | |
2531 | ||
2532 | /* issue a swapon-time discard if it's still required */ | |
2533 | if (p->flags & SWP_AREA_DISCARD) { | |
2534 | int err = discard_swap(p); | |
2535 | if (unlikely(err)) | |
2536 | pr_err("swapon: discard_swap(%p): %d\n", | |
2537 | p, err); | |
dcf6b7dd | 2538 | } |
20137a49 | 2539 | } |
6a6ba831 | 2540 | |
fc0abb14 | 2541 | mutex_lock(&swapon_mutex); |
40531542 | 2542 | prio = -1; |
78ecba08 | 2543 | if (swap_flags & SWAP_FLAG_PREFER) |
40531542 | 2544 | prio = |
78ecba08 | 2545 | (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; |
2a8f9449 | 2546 | enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map); |
c69dbfb8 | 2547 | |
756a025f | 2548 | pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n", |
91a27b2a | 2549 | p->pages<<(PAGE_SHIFT-10), name->name, p->prio, |
c69dbfb8 CEB |
2550 | nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), |
2551 | (p->flags & SWP_SOLIDSTATE) ? "SS" : "", | |
38b5faf4 | 2552 | (p->flags & SWP_DISCARDABLE) ? "D" : "", |
dcf6b7dd RA |
2553 | (p->flags & SWP_AREA_DISCARD) ? "s" : "", |
2554 | (p->flags & SWP_PAGE_DISCARD) ? "c" : "", | |
38b5faf4 | 2555 | (frontswap_map) ? "FS" : ""); |
c69dbfb8 | 2556 | |
fc0abb14 | 2557 | mutex_unlock(&swapon_mutex); |
66d7dd51 KS |
2558 | atomic_inc(&proc_poll_event); |
2559 | wake_up_interruptible(&proc_poll_wait); | |
2560 | ||
9b01c350 CEB |
2561 | if (S_ISREG(inode->i_mode)) |
2562 | inode->i_flags |= S_SWAPFILE; | |
1da177e4 LT |
2563 | error = 0; |
2564 | goto out; | |
2565 | bad_swap: | |
ebc2a1a6 SL |
2566 | free_percpu(p->percpu_cluster); |
2567 | p->percpu_cluster = NULL; | |
bd69010b | 2568 | if (inode && S_ISBLK(inode->i_mode) && p->bdev) { |
f2090d2d CEB |
2569 | set_blocksize(p->bdev, p->old_block_size); |
2570 | blkdev_put(p->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); | |
1da177e4 | 2571 | } |
4cd3bb10 | 2572 | destroy_swap_extents(p); |
e8e6c2ec | 2573 | swap_cgroup_swapoff(p->type); |
5d337b91 | 2574 | spin_lock(&swap_lock); |
1da177e4 | 2575 | p->swap_file = NULL; |
1da177e4 | 2576 | p->flags = 0; |
5d337b91 | 2577 | spin_unlock(&swap_lock); |
1da177e4 | 2578 | vfree(swap_map); |
2a8f9449 | 2579 | vfree(cluster_info); |
52c50567 | 2580 | if (swap_file) { |
2130781e | 2581 | if (inode && S_ISREG(inode->i_mode)) { |
5955102c | 2582 | inode_unlock(inode); |
2130781e CEB |
2583 | inode = NULL; |
2584 | } | |
1da177e4 | 2585 | filp_close(swap_file, NULL); |
52c50567 | 2586 | } |
1da177e4 LT |
2587 | out: |
2588 | if (page && !IS_ERR(page)) { | |
2589 | kunmap(page); | |
09cbfeaf | 2590 | put_page(page); |
1da177e4 LT |
2591 | } |
2592 | if (name) | |
2593 | putname(name); | |
9b01c350 | 2594 | if (inode && S_ISREG(inode->i_mode)) |
5955102c | 2595 | inode_unlock(inode); |
1da177e4 LT |
2596 | return error; |
2597 | } | |
2598 | ||
2599 | void si_swapinfo(struct sysinfo *val) | |
2600 | { | |
efa90a98 | 2601 | unsigned int type; |
1da177e4 LT |
2602 | unsigned long nr_to_be_unused = 0; |
2603 | ||
5d337b91 | 2604 | spin_lock(&swap_lock); |
efa90a98 HD |
2605 | for (type = 0; type < nr_swapfiles; type++) { |
2606 | struct swap_info_struct *si = swap_info[type]; | |
2607 | ||
2608 | if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK)) | |
2609 | nr_to_be_unused += si->inuse_pages; | |
1da177e4 | 2610 | } |
ec8acf20 | 2611 | val->freeswap = atomic_long_read(&nr_swap_pages) + nr_to_be_unused; |
1da177e4 | 2612 | val->totalswap = total_swap_pages + nr_to_be_unused; |
5d337b91 | 2613 | spin_unlock(&swap_lock); |
1da177e4 LT |
2614 | } |
2615 | ||
2616 | /* | |
2617 | * Verify that a swap entry is valid and increment its swap map count. | |
2618 | * | |
355cfa73 KH |
2619 | * Returns error code in following case. |
2620 | * - success -> 0 | |
2621 | * - swp_entry is invalid -> EINVAL | |
2622 | * - swp_entry is migration entry -> EINVAL | |
2623 | * - swap-cache reference is requested but there is already one. -> EEXIST | |
2624 | * - swap-cache reference is requested but the entry is not used. -> ENOENT | |
570a335b | 2625 | * - swap-mapped reference requested but needs continued swap count. -> ENOMEM |
1da177e4 | 2626 | */ |
8d69aaee | 2627 | static int __swap_duplicate(swp_entry_t entry, unsigned char usage) |
1da177e4 | 2628 | { |
73c34b6a | 2629 | struct swap_info_struct *p; |
1da177e4 | 2630 | unsigned long offset, type; |
8d69aaee HD |
2631 | unsigned char count; |
2632 | unsigned char has_cache; | |
253d553b | 2633 | int err = -EINVAL; |
1da177e4 | 2634 | |
a7420aa5 | 2635 | if (non_swap_entry(entry)) |
253d553b | 2636 | goto out; |
0697212a | 2637 | |
1da177e4 LT |
2638 | type = swp_type(entry); |
2639 | if (type >= nr_swapfiles) | |
2640 | goto bad_file; | |
efa90a98 | 2641 | p = swap_info[type]; |
1da177e4 LT |
2642 | offset = swp_offset(entry); |
2643 | ||
ec8acf20 | 2644 | spin_lock(&p->lock); |
355cfa73 KH |
2645 | if (unlikely(offset >= p->max)) |
2646 | goto unlock_out; | |
2647 | ||
253d553b | 2648 | count = p->swap_map[offset]; |
edfe23da SL |
2649 | |
2650 | /* | |
2651 | * swapin_readahead() doesn't check if a swap entry is valid, so the | |
2652 | * swap entry could be SWAP_MAP_BAD. Check here with lock held. | |
2653 | */ | |
2654 | if (unlikely(swap_count(count) == SWAP_MAP_BAD)) { | |
2655 | err = -ENOENT; | |
2656 | goto unlock_out; | |
2657 | } | |
2658 | ||
253d553b HD |
2659 | has_cache = count & SWAP_HAS_CACHE; |
2660 | count &= ~SWAP_HAS_CACHE; | |
2661 | err = 0; | |
355cfa73 | 2662 | |
253d553b | 2663 | if (usage == SWAP_HAS_CACHE) { |
355cfa73 KH |
2664 | |
2665 | /* set SWAP_HAS_CACHE if there is no cache and entry is used */ | |
253d553b HD |
2666 | if (!has_cache && count) |
2667 | has_cache = SWAP_HAS_CACHE; | |
2668 | else if (has_cache) /* someone else added cache */ | |
2669 | err = -EEXIST; | |
2670 | else /* no users remaining */ | |
2671 | err = -ENOENT; | |
355cfa73 KH |
2672 | |
2673 | } else if (count || has_cache) { | |
253d553b | 2674 | |
570a335b HD |
2675 | if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX) |
2676 | count += usage; | |
2677 | else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) | |
253d553b | 2678 | err = -EINVAL; |
570a335b HD |
2679 | else if (swap_count_continued(p, offset, count)) |
2680 | count = COUNT_CONTINUED; | |
2681 | else | |
2682 | err = -ENOMEM; | |
355cfa73 | 2683 | } else |
253d553b HD |
2684 | err = -ENOENT; /* unused swap entry */ |
2685 | ||
2686 | p->swap_map[offset] = count | has_cache; | |
2687 | ||
355cfa73 | 2688 | unlock_out: |
ec8acf20 | 2689 | spin_unlock(&p->lock); |
1da177e4 | 2690 | out: |
253d553b | 2691 | return err; |
1da177e4 LT |
2692 | |
2693 | bad_file: | |
465c47fd | 2694 | pr_err("swap_dup: %s%08lx\n", Bad_file, entry.val); |
1da177e4 LT |
2695 | goto out; |
2696 | } | |
253d553b | 2697 | |
aaa46865 HD |
2698 | /* |
2699 | * Help swapoff by noting that swap entry belongs to shmem/tmpfs | |
2700 | * (in which case its reference count is never incremented). | |
2701 | */ | |
2702 | void swap_shmem_alloc(swp_entry_t entry) | |
2703 | { | |
2704 | __swap_duplicate(entry, SWAP_MAP_SHMEM); | |
2705 | } | |
2706 | ||
355cfa73 | 2707 | /* |
08259d58 HD |
2708 | * Increase reference count of swap entry by 1. |
2709 | * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required | |
2710 | * but could not be atomically allocated. Returns 0, just as if it succeeded, | |
2711 | * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which | |
2712 | * might occur if a page table entry has got corrupted. | |
355cfa73 | 2713 | */ |
570a335b | 2714 | int swap_duplicate(swp_entry_t entry) |
355cfa73 | 2715 | { |
570a335b HD |
2716 | int err = 0; |
2717 | ||
2718 | while (!err && __swap_duplicate(entry, 1) == -ENOMEM) | |
2719 | err = add_swap_count_continuation(entry, GFP_ATOMIC); | |
2720 | return err; | |
355cfa73 | 2721 | } |
1da177e4 | 2722 | |
cb4b86ba | 2723 | /* |
355cfa73 KH |
2724 | * @entry: swap entry for which we allocate swap cache. |
2725 | * | |
73c34b6a | 2726 | * Called when allocating swap cache for existing swap entry, |
355cfa73 KH |
2727 | * This can return error codes. Returns 0 at success. |
2728 | * -EBUSY means there is a swap cache. | |
2729 | * Note: return code is different from swap_duplicate(). | |
cb4b86ba KH |
2730 | */ |
2731 | int swapcache_prepare(swp_entry_t entry) | |
2732 | { | |
253d553b | 2733 | return __swap_duplicate(entry, SWAP_HAS_CACHE); |
cb4b86ba KH |
2734 | } |
2735 | ||
f981c595 MG |
2736 | struct swap_info_struct *page_swap_info(struct page *page) |
2737 | { | |
2738 | swp_entry_t swap = { .val = page_private(page) }; | |
f981c595 MG |
2739 | return swap_info[swp_type(swap)]; |
2740 | } | |
2741 | ||
2742 | /* | |
2743 | * out-of-line __page_file_ methods to avoid include hell. | |
2744 | */ | |
2745 | struct address_space *__page_file_mapping(struct page *page) | |
2746 | { | |
309381fe | 2747 | VM_BUG_ON_PAGE(!PageSwapCache(page), page); |
f981c595 MG |
2748 | return page_swap_info(page)->swap_file->f_mapping; |
2749 | } | |
2750 | EXPORT_SYMBOL_GPL(__page_file_mapping); | |
2751 | ||
2752 | pgoff_t __page_file_index(struct page *page) | |
2753 | { | |
2754 | swp_entry_t swap = { .val = page_private(page) }; | |
309381fe | 2755 | VM_BUG_ON_PAGE(!PageSwapCache(page), page); |
f981c595 MG |
2756 | return swp_offset(swap); |
2757 | } | |
2758 | EXPORT_SYMBOL_GPL(__page_file_index); | |
2759 | ||
570a335b HD |
2760 | /* |
2761 | * add_swap_count_continuation - called when a swap count is duplicated | |
2762 | * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's | |
2763 | * page of the original vmalloc'ed swap_map, to hold the continuation count | |
2764 | * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called | |
2765 | * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc. | |
2766 | * | |
2767 | * These continuation pages are seldom referenced: the common paths all work | |
2768 | * on the original swap_map, only referring to a continuation page when the | |
2769 | * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX. | |
2770 | * | |
2771 | * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding | |
2772 | * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL) | |
2773 | * can be called after dropping locks. | |
2774 | */ | |
2775 | int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask) | |
2776 | { | |
2777 | struct swap_info_struct *si; | |
2778 | struct page *head; | |
2779 | struct page *page; | |
2780 | struct page *list_page; | |
2781 | pgoff_t offset; | |
2782 | unsigned char count; | |
2783 | ||
2784 | /* | |
2785 | * When debugging, it's easier to use __GFP_ZERO here; but it's better | |
2786 | * for latency not to zero a page while GFP_ATOMIC and holding locks. | |
2787 | */ | |
2788 | page = alloc_page(gfp_mask | __GFP_HIGHMEM); | |
2789 | ||
2790 | si = swap_info_get(entry); | |
2791 | if (!si) { | |
2792 | /* | |
2793 | * An acceptable race has occurred since the failing | |
2794 | * __swap_duplicate(): the swap entry has been freed, | |
2795 | * perhaps even the whole swap_map cleared for swapoff. | |
2796 | */ | |
2797 | goto outer; | |
2798 | } | |
2799 | ||
2800 | offset = swp_offset(entry); | |
2801 | count = si->swap_map[offset] & ~SWAP_HAS_CACHE; | |
2802 | ||
2803 | if ((count & ~COUNT_CONTINUED) != SWAP_MAP_MAX) { | |
2804 | /* | |
2805 | * The higher the swap count, the more likely it is that tasks | |
2806 | * will race to add swap count continuation: we need to avoid | |
2807 | * over-provisioning. | |
2808 | */ | |
2809 | goto out; | |
2810 | } | |
2811 | ||
2812 | if (!page) { | |
ec8acf20 | 2813 | spin_unlock(&si->lock); |
570a335b HD |
2814 | return -ENOMEM; |
2815 | } | |
2816 | ||
2817 | /* | |
2818 | * We are fortunate that although vmalloc_to_page uses pte_offset_map, | |
2de1a7e4 SJ |
2819 | * no architecture is using highmem pages for kernel page tables: so it |
2820 | * will not corrupt the GFP_ATOMIC caller's atomic page table kmaps. | |
570a335b HD |
2821 | */ |
2822 | head = vmalloc_to_page(si->swap_map + offset); | |
2823 | offset &= ~PAGE_MASK; | |
2824 | ||
2825 | /* | |
2826 | * Page allocation does not initialize the page's lru field, | |
2827 | * but it does always reset its private field. | |
2828 | */ | |
2829 | if (!page_private(head)) { | |
2830 | BUG_ON(count & COUNT_CONTINUED); | |
2831 | INIT_LIST_HEAD(&head->lru); | |
2832 | set_page_private(head, SWP_CONTINUED); | |
2833 | si->flags |= SWP_CONTINUED; | |
2834 | } | |
2835 | ||
2836 | list_for_each_entry(list_page, &head->lru, lru) { | |
2837 | unsigned char *map; | |
2838 | ||
2839 | /* | |
2840 | * If the previous map said no continuation, but we've found | |
2841 | * a continuation page, free our allocation and use this one. | |
2842 | */ | |
2843 | if (!(count & COUNT_CONTINUED)) | |
2844 | goto out; | |
2845 | ||
9b04c5fe | 2846 | map = kmap_atomic(list_page) + offset; |
570a335b | 2847 | count = *map; |
9b04c5fe | 2848 | kunmap_atomic(map); |
570a335b HD |
2849 | |
2850 | /* | |
2851 | * If this continuation count now has some space in it, | |
2852 | * free our allocation and use this one. | |
2853 | */ | |
2854 | if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX) | |
2855 | goto out; | |
2856 | } | |
2857 | ||
2858 | list_add_tail(&page->lru, &head->lru); | |
2859 | page = NULL; /* now it's attached, don't free it */ | |
2860 | out: | |
ec8acf20 | 2861 | spin_unlock(&si->lock); |
570a335b HD |
2862 | outer: |
2863 | if (page) | |
2864 | __free_page(page); | |
2865 | return 0; | |
2866 | } | |
2867 | ||
2868 | /* | |
2869 | * swap_count_continued - when the original swap_map count is incremented | |
2870 | * from SWAP_MAP_MAX, check if there is already a continuation page to carry | |
2871 | * into, carry if so, or else fail until a new continuation page is allocated; | |
2872 | * when the original swap_map count is decremented from 0 with continuation, | |
2873 | * borrow from the continuation and report whether it still holds more. | |
2874 | * Called while __swap_duplicate() or swap_entry_free() holds swap_lock. | |
2875 | */ | |
2876 | static bool swap_count_continued(struct swap_info_struct *si, | |
2877 | pgoff_t offset, unsigned char count) | |
2878 | { | |
2879 | struct page *head; | |
2880 | struct page *page; | |
2881 | unsigned char *map; | |
2882 | ||
2883 | head = vmalloc_to_page(si->swap_map + offset); | |
2884 | if (page_private(head) != SWP_CONTINUED) { | |
2885 | BUG_ON(count & COUNT_CONTINUED); | |
2886 | return false; /* need to add count continuation */ | |
2887 | } | |
2888 | ||
2889 | offset &= ~PAGE_MASK; | |
2890 | page = list_entry(head->lru.next, struct page, lru); | |
9b04c5fe | 2891 | map = kmap_atomic(page) + offset; |
570a335b HD |
2892 | |
2893 | if (count == SWAP_MAP_MAX) /* initial increment from swap_map */ | |
2894 | goto init_map; /* jump over SWAP_CONT_MAX checks */ | |
2895 | ||
2896 | if (count == (SWAP_MAP_MAX | COUNT_CONTINUED)) { /* incrementing */ | |
2897 | /* | |
2898 | * Think of how you add 1 to 999 | |
2899 | */ | |
2900 | while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) { | |
9b04c5fe | 2901 | kunmap_atomic(map); |
570a335b HD |
2902 | page = list_entry(page->lru.next, struct page, lru); |
2903 | BUG_ON(page == head); | |
9b04c5fe | 2904 | map = kmap_atomic(page) + offset; |
570a335b HD |
2905 | } |
2906 | if (*map == SWAP_CONT_MAX) { | |
9b04c5fe | 2907 | kunmap_atomic(map); |
570a335b HD |
2908 | page = list_entry(page->lru.next, struct page, lru); |
2909 | if (page == head) | |
2910 | return false; /* add count continuation */ | |
9b04c5fe | 2911 | map = kmap_atomic(page) + offset; |
570a335b HD |
2912 | init_map: *map = 0; /* we didn't zero the page */ |
2913 | } | |
2914 | *map += 1; | |
9b04c5fe | 2915 | kunmap_atomic(map); |
570a335b HD |
2916 | page = list_entry(page->lru.prev, struct page, lru); |
2917 | while (page != head) { | |
9b04c5fe | 2918 | map = kmap_atomic(page) + offset; |
570a335b | 2919 | *map = COUNT_CONTINUED; |
9b04c5fe | 2920 | kunmap_atomic(map); |
570a335b HD |
2921 | page = list_entry(page->lru.prev, struct page, lru); |
2922 | } | |
2923 | return true; /* incremented */ | |
2924 | ||
2925 | } else { /* decrementing */ | |
2926 | /* | |
2927 | * Think of how you subtract 1 from 1000 | |
2928 | */ | |
2929 | BUG_ON(count != COUNT_CONTINUED); | |
2930 | while (*map == COUNT_CONTINUED) { | |
9b04c5fe | 2931 | kunmap_atomic(map); |
570a335b HD |
2932 | page = list_entry(page->lru.next, struct page, lru); |
2933 | BUG_ON(page == head); | |
9b04c5fe | 2934 | map = kmap_atomic(page) + offset; |
570a335b HD |
2935 | } |
2936 | BUG_ON(*map == 0); | |
2937 | *map -= 1; | |
2938 | if (*map == 0) | |
2939 | count = 0; | |
9b04c5fe | 2940 | kunmap_atomic(map); |
570a335b HD |
2941 | page = list_entry(page->lru.prev, struct page, lru); |
2942 | while (page != head) { | |
9b04c5fe | 2943 | map = kmap_atomic(page) + offset; |
570a335b HD |
2944 | *map = SWAP_CONT_MAX | count; |
2945 | count = COUNT_CONTINUED; | |
9b04c5fe | 2946 | kunmap_atomic(map); |
570a335b HD |
2947 | page = list_entry(page->lru.prev, struct page, lru); |
2948 | } | |
2949 | return count == COUNT_CONTINUED; | |
2950 | } | |
2951 | } | |
2952 | ||
2953 | /* | |
2954 | * free_swap_count_continuations - swapoff free all the continuation pages | |
2955 | * appended to the swap_map, after swap_map is quiesced, before vfree'ing it. | |
2956 | */ | |
2957 | static void free_swap_count_continuations(struct swap_info_struct *si) | |
2958 | { | |
2959 | pgoff_t offset; | |
2960 | ||
2961 | for (offset = 0; offset < si->max; offset += PAGE_SIZE) { | |
2962 | struct page *head; | |
2963 | head = vmalloc_to_page(si->swap_map + offset); | |
2964 | if (page_private(head)) { | |
0d576d20 GT |
2965 | struct page *page, *next; |
2966 | ||
2967 | list_for_each_entry_safe(page, next, &head->lru, lru) { | |
2968 | list_del(&page->lru); | |
570a335b HD |
2969 | __free_page(page); |
2970 | } | |
2971 | } | |
2972 | } | |
2973 | } |