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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> | |
17 | #include <linux/shm.h> | |
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> | |
24 | #include <linux/module.h> | |
5ad64688 | 25 | #include <linux/ksm.h> |
1da177e4 LT |
26 | #include <linux/rmap.h> |
27 | #include <linux/security.h> | |
28 | #include <linux/backing-dev.h> | |
fc0abb14 | 29 | #include <linux/mutex.h> |
c59ede7b | 30 | #include <linux/capability.h> |
1da177e4 | 31 | #include <linux/syscalls.h> |
8a9f3ccd | 32 | #include <linux/memcontrol.h> |
1da177e4 LT |
33 | |
34 | #include <asm/pgtable.h> | |
35 | #include <asm/tlbflush.h> | |
36 | #include <linux/swapops.h> | |
27a7faa0 | 37 | #include <linux/page_cgroup.h> |
1da177e4 | 38 | |
570a335b HD |
39 | static bool swap_count_continued(struct swap_info_struct *, pgoff_t, |
40 | unsigned char); | |
41 | static void free_swap_count_continuations(struct swap_info_struct *); | |
d4906e1a | 42 | static sector_t map_swap_entry(swp_entry_t, struct block_device**); |
570a335b | 43 | |
7c363b8c AB |
44 | static DEFINE_SPINLOCK(swap_lock); |
45 | static unsigned int nr_swapfiles; | |
b962716b | 46 | long nr_swap_pages; |
1da177e4 | 47 | long total_swap_pages; |
78ecba08 | 48 | static int least_priority; |
1da177e4 | 49 | |
1da177e4 LT |
50 | static const char Bad_file[] = "Bad swap file entry "; |
51 | static const char Unused_file[] = "Unused swap file entry "; | |
52 | static const char Bad_offset[] = "Bad swap offset entry "; | |
53 | static const char Unused_offset[] = "Unused swap offset entry "; | |
54 | ||
7c363b8c | 55 | static struct swap_list_t swap_list = {-1, -1}; |
1da177e4 | 56 | |
efa90a98 | 57 | static struct swap_info_struct *swap_info[MAX_SWAPFILES]; |
1da177e4 | 58 | |
fc0abb14 | 59 | static DEFINE_MUTEX(swapon_mutex); |
1da177e4 | 60 | |
8d69aaee | 61 | static inline unsigned char swap_count(unsigned char ent) |
355cfa73 | 62 | { |
570a335b | 63 | return ent & ~SWAP_HAS_CACHE; /* may include SWAP_HAS_CONT flag */ |
355cfa73 KH |
64 | } |
65 | ||
efa90a98 | 66 | /* returns 1 if swap entry is freed */ |
c9e44410 KH |
67 | static int |
68 | __try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset) | |
69 | { | |
efa90a98 | 70 | swp_entry_t entry = swp_entry(si->type, offset); |
c9e44410 KH |
71 | struct page *page; |
72 | int ret = 0; | |
73 | ||
74 | page = find_get_page(&swapper_space, entry.val); | |
75 | if (!page) | |
76 | return 0; | |
77 | /* | |
78 | * This function is called from scan_swap_map() and it's called | |
79 | * by vmscan.c at reclaiming pages. So, we hold a lock on a page, here. | |
80 | * We have to use trylock for avoiding deadlock. This is a special | |
81 | * case and you should use try_to_free_swap() with explicit lock_page() | |
82 | * in usual operations. | |
83 | */ | |
84 | if (trylock_page(page)) { | |
85 | ret = try_to_free_swap(page); | |
86 | unlock_page(page); | |
87 | } | |
88 | page_cache_release(page); | |
89 | return ret; | |
90 | } | |
355cfa73 | 91 | |
1da177e4 LT |
92 | /* |
93 | * We need this because the bdev->unplug_fn can sleep and we cannot | |
5d337b91 | 94 | * hold swap_lock while calling the unplug_fn. And swap_lock |
fc0abb14 | 95 | * cannot be turned into a mutex. |
1da177e4 LT |
96 | */ |
97 | static DECLARE_RWSEM(swap_unplug_sem); | |
98 | ||
1da177e4 LT |
99 | void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page) |
100 | { | |
101 | swp_entry_t entry; | |
102 | ||
103 | down_read(&swap_unplug_sem); | |
4c21e2f2 | 104 | entry.val = page_private(page); |
1da177e4 | 105 | if (PageSwapCache(page)) { |
efa90a98 | 106 | struct block_device *bdev = swap_info[swp_type(entry)]->bdev; |
1da177e4 LT |
107 | struct backing_dev_info *bdi; |
108 | ||
109 | /* | |
110 | * If the page is removed from swapcache from under us (with a | |
111 | * racy try_to_unuse/swapoff) we need an additional reference | |
4c21e2f2 HD |
112 | * count to avoid reading garbage from page_private(page) above. |
113 | * If the WARN_ON triggers during a swapoff it maybe the race | |
1da177e4 LT |
114 | * condition and it's harmless. However if it triggers without |
115 | * swapoff it signals a problem. | |
116 | */ | |
117 | WARN_ON(page_count(page) <= 1); | |
118 | ||
119 | bdi = bdev->bd_inode->i_mapping->backing_dev_info; | |
ba32311e | 120 | blk_run_backing_dev(bdi, page); |
1da177e4 LT |
121 | } |
122 | up_read(&swap_unplug_sem); | |
123 | } | |
124 | ||
6a6ba831 HD |
125 | /* |
126 | * swapon tell device that all the old swap contents can be discarded, | |
127 | * to allow the swap device to optimize its wear-levelling. | |
128 | */ | |
129 | static int discard_swap(struct swap_info_struct *si) | |
130 | { | |
131 | struct swap_extent *se; | |
9625a5f2 HD |
132 | sector_t start_block; |
133 | sector_t nr_blocks; | |
6a6ba831 HD |
134 | int err = 0; |
135 | ||
9625a5f2 HD |
136 | /* Do not discard the swap header page! */ |
137 | se = &si->first_swap_extent; | |
138 | start_block = (se->start_block + 1) << (PAGE_SHIFT - 9); | |
139 | nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9); | |
140 | if (nr_blocks) { | |
141 | err = blkdev_issue_discard(si->bdev, start_block, | |
142 | nr_blocks, GFP_KERNEL, DISCARD_FL_BARRIER); | |
143 | if (err) | |
144 | return err; | |
145 | cond_resched(); | |
146 | } | |
6a6ba831 | 147 | |
9625a5f2 HD |
148 | list_for_each_entry(se, &si->first_swap_extent.list, list) { |
149 | start_block = se->start_block << (PAGE_SHIFT - 9); | |
150 | nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); | |
6a6ba831 HD |
151 | |
152 | err = blkdev_issue_discard(si->bdev, start_block, | |
9625a5f2 | 153 | nr_blocks, GFP_KERNEL, DISCARD_FL_BARRIER); |
6a6ba831 HD |
154 | if (err) |
155 | break; | |
156 | ||
157 | cond_resched(); | |
158 | } | |
159 | return err; /* That will often be -EOPNOTSUPP */ | |
160 | } | |
161 | ||
7992fde7 HD |
162 | /* |
163 | * swap allocation tell device that a cluster of swap can now be discarded, | |
164 | * to allow the swap device to optimize its wear-levelling. | |
165 | */ | |
166 | static void discard_swap_cluster(struct swap_info_struct *si, | |
167 | pgoff_t start_page, pgoff_t nr_pages) | |
168 | { | |
169 | struct swap_extent *se = si->curr_swap_extent; | |
170 | int found_extent = 0; | |
171 | ||
172 | while (nr_pages) { | |
173 | struct list_head *lh; | |
174 | ||
175 | if (se->start_page <= start_page && | |
176 | start_page < se->start_page + se->nr_pages) { | |
177 | pgoff_t offset = start_page - se->start_page; | |
178 | sector_t start_block = se->start_block + offset; | |
858a2990 | 179 | sector_t nr_blocks = se->nr_pages - offset; |
7992fde7 HD |
180 | |
181 | if (nr_blocks > nr_pages) | |
182 | nr_blocks = nr_pages; | |
183 | start_page += nr_blocks; | |
184 | nr_pages -= nr_blocks; | |
185 | ||
186 | if (!found_extent++) | |
187 | si->curr_swap_extent = se; | |
188 | ||
189 | start_block <<= PAGE_SHIFT - 9; | |
190 | nr_blocks <<= PAGE_SHIFT - 9; | |
191 | if (blkdev_issue_discard(si->bdev, start_block, | |
9625a5f2 | 192 | nr_blocks, GFP_NOIO, DISCARD_FL_BARRIER)) |
7992fde7 HD |
193 | break; |
194 | } | |
195 | ||
196 | lh = se->list.next; | |
7992fde7 HD |
197 | se = list_entry(lh, struct swap_extent, list); |
198 | } | |
199 | } | |
200 | ||
201 | static int wait_for_discard(void *word) | |
202 | { | |
203 | schedule(); | |
204 | return 0; | |
205 | } | |
206 | ||
048c27fd HD |
207 | #define SWAPFILE_CLUSTER 256 |
208 | #define LATENCY_LIMIT 256 | |
209 | ||
355cfa73 | 210 | static inline unsigned long scan_swap_map(struct swap_info_struct *si, |
8d69aaee | 211 | unsigned char usage) |
1da177e4 | 212 | { |
ebebbbe9 | 213 | unsigned long offset; |
c60aa176 | 214 | unsigned long scan_base; |
7992fde7 | 215 | unsigned long last_in_cluster = 0; |
048c27fd | 216 | int latency_ration = LATENCY_LIMIT; |
7992fde7 | 217 | int found_free_cluster = 0; |
7dfad418 | 218 | |
886bb7e9 | 219 | /* |
7dfad418 HD |
220 | * We try to cluster swap pages by allocating them sequentially |
221 | * in swap. Once we've allocated SWAPFILE_CLUSTER pages this | |
222 | * way, however, we resort to first-free allocation, starting | |
223 | * a new cluster. This prevents us from scattering swap pages | |
224 | * all over the entire swap partition, so that we reduce | |
225 | * overall disk seek times between swap pages. -- sct | |
226 | * But we do now try to find an empty cluster. -Andrea | |
c60aa176 | 227 | * And we let swap pages go all over an SSD partition. Hugh |
7dfad418 HD |
228 | */ |
229 | ||
52b7efdb | 230 | si->flags += SWP_SCANNING; |
c60aa176 | 231 | scan_base = offset = si->cluster_next; |
ebebbbe9 HD |
232 | |
233 | if (unlikely(!si->cluster_nr--)) { | |
234 | if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { | |
235 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
236 | goto checks; | |
237 | } | |
7992fde7 HD |
238 | if (si->flags & SWP_DISCARDABLE) { |
239 | /* | |
240 | * Start range check on racing allocations, in case | |
241 | * they overlap the cluster we eventually decide on | |
242 | * (we scan without swap_lock to allow preemption). | |
243 | * It's hardly conceivable that cluster_nr could be | |
244 | * wrapped during our scan, but don't depend on it. | |
245 | */ | |
246 | if (si->lowest_alloc) | |
247 | goto checks; | |
248 | si->lowest_alloc = si->max; | |
249 | si->highest_alloc = 0; | |
250 | } | |
5d337b91 | 251 | spin_unlock(&swap_lock); |
7dfad418 | 252 | |
c60aa176 HD |
253 | /* |
254 | * If seek is expensive, start searching for new cluster from | |
255 | * start of partition, to minimize the span of allocated swap. | |
256 | * But if seek is cheap, search from our current position, so | |
257 | * that swap is allocated from all over the partition: if the | |
258 | * Flash Translation Layer only remaps within limited zones, | |
259 | * we don't want to wear out the first zone too quickly. | |
260 | */ | |
261 | if (!(si->flags & SWP_SOLIDSTATE)) | |
262 | scan_base = offset = si->lowest_bit; | |
7dfad418 HD |
263 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
264 | ||
265 | /* Locate the first empty (unaligned) cluster */ | |
266 | for (; last_in_cluster <= si->highest_bit; offset++) { | |
1da177e4 | 267 | if (si->swap_map[offset]) |
7dfad418 HD |
268 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
269 | else if (offset == last_in_cluster) { | |
5d337b91 | 270 | spin_lock(&swap_lock); |
ebebbbe9 HD |
271 | offset -= SWAPFILE_CLUSTER - 1; |
272 | si->cluster_next = offset; | |
273 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
7992fde7 | 274 | found_free_cluster = 1; |
ebebbbe9 | 275 | goto checks; |
1da177e4 | 276 | } |
048c27fd HD |
277 | if (unlikely(--latency_ration < 0)) { |
278 | cond_resched(); | |
279 | latency_ration = LATENCY_LIMIT; | |
280 | } | |
7dfad418 | 281 | } |
ebebbbe9 HD |
282 | |
283 | offset = si->lowest_bit; | |
c60aa176 HD |
284 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
285 | ||
286 | /* Locate the first empty (unaligned) cluster */ | |
287 | for (; last_in_cluster < scan_base; offset++) { | |
288 | if (si->swap_map[offset]) | |
289 | last_in_cluster = offset + SWAPFILE_CLUSTER; | |
290 | else if (offset == last_in_cluster) { | |
291 | spin_lock(&swap_lock); | |
292 | offset -= SWAPFILE_CLUSTER - 1; | |
293 | si->cluster_next = offset; | |
294 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
295 | found_free_cluster = 1; | |
296 | goto checks; | |
297 | } | |
298 | if (unlikely(--latency_ration < 0)) { | |
299 | cond_resched(); | |
300 | latency_ration = LATENCY_LIMIT; | |
301 | } | |
302 | } | |
303 | ||
304 | offset = scan_base; | |
5d337b91 | 305 | spin_lock(&swap_lock); |
ebebbbe9 | 306 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
7992fde7 | 307 | si->lowest_alloc = 0; |
1da177e4 | 308 | } |
7dfad418 | 309 | |
ebebbbe9 HD |
310 | checks: |
311 | if (!(si->flags & SWP_WRITEOK)) | |
52b7efdb | 312 | goto no_page; |
7dfad418 HD |
313 | if (!si->highest_bit) |
314 | goto no_page; | |
ebebbbe9 | 315 | if (offset > si->highest_bit) |
c60aa176 | 316 | scan_base = offset = si->lowest_bit; |
c9e44410 KH |
317 | |
318 | /* reuse swap entry of cache-only swap if not busy. */ | |
319 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { | |
320 | int swap_was_freed; | |
321 | spin_unlock(&swap_lock); | |
322 | swap_was_freed = __try_to_reclaim_swap(si, offset); | |
323 | spin_lock(&swap_lock); | |
324 | /* entry was freed successfully, try to use this again */ | |
325 | if (swap_was_freed) | |
326 | goto checks; | |
327 | goto scan; /* check next one */ | |
328 | } | |
329 | ||
ebebbbe9 HD |
330 | if (si->swap_map[offset]) |
331 | goto scan; | |
332 | ||
333 | if (offset == si->lowest_bit) | |
334 | si->lowest_bit++; | |
335 | if (offset == si->highest_bit) | |
336 | si->highest_bit--; | |
337 | si->inuse_pages++; | |
338 | if (si->inuse_pages == si->pages) { | |
339 | si->lowest_bit = si->max; | |
340 | si->highest_bit = 0; | |
1da177e4 | 341 | } |
253d553b | 342 | si->swap_map[offset] = usage; |
ebebbbe9 HD |
343 | si->cluster_next = offset + 1; |
344 | si->flags -= SWP_SCANNING; | |
7992fde7 HD |
345 | |
346 | if (si->lowest_alloc) { | |
347 | /* | |
348 | * Only set when SWP_DISCARDABLE, and there's a scan | |
349 | * for a free cluster in progress or just completed. | |
350 | */ | |
351 | if (found_free_cluster) { | |
352 | /* | |
353 | * To optimize wear-levelling, discard the | |
354 | * old data of the cluster, taking care not to | |
355 | * discard any of its pages that have already | |
356 | * been allocated by racing tasks (offset has | |
357 | * already stepped over any at the beginning). | |
358 | */ | |
359 | if (offset < si->highest_alloc && | |
360 | si->lowest_alloc <= last_in_cluster) | |
361 | last_in_cluster = si->lowest_alloc - 1; | |
362 | si->flags |= SWP_DISCARDING; | |
363 | spin_unlock(&swap_lock); | |
364 | ||
365 | if (offset < last_in_cluster) | |
366 | discard_swap_cluster(si, offset, | |
367 | last_in_cluster - offset + 1); | |
368 | ||
369 | spin_lock(&swap_lock); | |
370 | si->lowest_alloc = 0; | |
371 | si->flags &= ~SWP_DISCARDING; | |
372 | ||
373 | smp_mb(); /* wake_up_bit advises this */ | |
374 | wake_up_bit(&si->flags, ilog2(SWP_DISCARDING)); | |
375 | ||
376 | } else if (si->flags & SWP_DISCARDING) { | |
377 | /* | |
378 | * Delay using pages allocated by racing tasks | |
379 | * until the whole discard has been issued. We | |
380 | * could defer that delay until swap_writepage, | |
381 | * but it's easier to keep this self-contained. | |
382 | */ | |
383 | spin_unlock(&swap_lock); | |
384 | wait_on_bit(&si->flags, ilog2(SWP_DISCARDING), | |
385 | wait_for_discard, TASK_UNINTERRUPTIBLE); | |
386 | spin_lock(&swap_lock); | |
387 | } else { | |
388 | /* | |
389 | * Note pages allocated by racing tasks while | |
390 | * scan for a free cluster is in progress, so | |
391 | * that its final discard can exclude them. | |
392 | */ | |
393 | if (offset < si->lowest_alloc) | |
394 | si->lowest_alloc = offset; | |
395 | if (offset > si->highest_alloc) | |
396 | si->highest_alloc = offset; | |
397 | } | |
398 | } | |
ebebbbe9 | 399 | return offset; |
7dfad418 | 400 | |
ebebbbe9 | 401 | scan: |
5d337b91 | 402 | spin_unlock(&swap_lock); |
7dfad418 | 403 | while (++offset <= si->highest_bit) { |
52b7efdb | 404 | if (!si->swap_map[offset]) { |
5d337b91 | 405 | spin_lock(&swap_lock); |
52b7efdb HD |
406 | goto checks; |
407 | } | |
c9e44410 KH |
408 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
409 | spin_lock(&swap_lock); | |
410 | goto checks; | |
411 | } | |
048c27fd HD |
412 | if (unlikely(--latency_ration < 0)) { |
413 | cond_resched(); | |
414 | latency_ration = LATENCY_LIMIT; | |
415 | } | |
7dfad418 | 416 | } |
c60aa176 HD |
417 | offset = si->lowest_bit; |
418 | while (++offset < scan_base) { | |
419 | if (!si->swap_map[offset]) { | |
420 | spin_lock(&swap_lock); | |
421 | goto checks; | |
422 | } | |
c9e44410 KH |
423 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
424 | spin_lock(&swap_lock); | |
425 | goto checks; | |
426 | } | |
c60aa176 HD |
427 | if (unlikely(--latency_ration < 0)) { |
428 | cond_resched(); | |
429 | latency_ration = LATENCY_LIMIT; | |
430 | } | |
431 | } | |
5d337b91 | 432 | spin_lock(&swap_lock); |
7dfad418 HD |
433 | |
434 | no_page: | |
52b7efdb | 435 | si->flags -= SWP_SCANNING; |
1da177e4 LT |
436 | return 0; |
437 | } | |
438 | ||
439 | swp_entry_t get_swap_page(void) | |
440 | { | |
fb4f88dc HD |
441 | struct swap_info_struct *si; |
442 | pgoff_t offset; | |
443 | int type, next; | |
444 | int wrapped = 0; | |
1da177e4 | 445 | |
5d337b91 | 446 | spin_lock(&swap_lock); |
1da177e4 | 447 | if (nr_swap_pages <= 0) |
fb4f88dc HD |
448 | goto noswap; |
449 | nr_swap_pages--; | |
450 | ||
451 | for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) { | |
efa90a98 | 452 | si = swap_info[type]; |
fb4f88dc HD |
453 | next = si->next; |
454 | if (next < 0 || | |
efa90a98 | 455 | (!wrapped && si->prio != swap_info[next]->prio)) { |
fb4f88dc HD |
456 | next = swap_list.head; |
457 | wrapped++; | |
1da177e4 | 458 | } |
fb4f88dc HD |
459 | |
460 | if (!si->highest_bit) | |
461 | continue; | |
462 | if (!(si->flags & SWP_WRITEOK)) | |
463 | continue; | |
464 | ||
465 | swap_list.next = next; | |
355cfa73 | 466 | /* This is called for allocating swap entry for cache */ |
253d553b | 467 | offset = scan_swap_map(si, SWAP_HAS_CACHE); |
5d337b91 HD |
468 | if (offset) { |
469 | spin_unlock(&swap_lock); | |
fb4f88dc | 470 | return swp_entry(type, offset); |
5d337b91 | 471 | } |
fb4f88dc | 472 | next = swap_list.next; |
1da177e4 | 473 | } |
fb4f88dc HD |
474 | |
475 | nr_swap_pages++; | |
476 | noswap: | |
5d337b91 | 477 | spin_unlock(&swap_lock); |
fb4f88dc | 478 | return (swp_entry_t) {0}; |
1da177e4 LT |
479 | } |
480 | ||
355cfa73 | 481 | /* The only caller of this function is now susupend routine */ |
3a291a20 RW |
482 | swp_entry_t get_swap_page_of_type(int type) |
483 | { | |
484 | struct swap_info_struct *si; | |
485 | pgoff_t offset; | |
486 | ||
487 | spin_lock(&swap_lock); | |
efa90a98 HD |
488 | si = swap_info[type]; |
489 | if (si && (si->flags & SWP_WRITEOK)) { | |
3a291a20 | 490 | nr_swap_pages--; |
355cfa73 | 491 | /* This is called for allocating swap entry, not cache */ |
253d553b | 492 | offset = scan_swap_map(si, 1); |
3a291a20 RW |
493 | if (offset) { |
494 | spin_unlock(&swap_lock); | |
495 | return swp_entry(type, offset); | |
496 | } | |
497 | nr_swap_pages++; | |
498 | } | |
499 | spin_unlock(&swap_lock); | |
500 | return (swp_entry_t) {0}; | |
501 | } | |
502 | ||
73c34b6a | 503 | static struct swap_info_struct *swap_info_get(swp_entry_t entry) |
1da177e4 | 504 | { |
73c34b6a | 505 | struct swap_info_struct *p; |
1da177e4 LT |
506 | unsigned long offset, type; |
507 | ||
508 | if (!entry.val) | |
509 | goto out; | |
510 | type = swp_type(entry); | |
511 | if (type >= nr_swapfiles) | |
512 | goto bad_nofile; | |
efa90a98 | 513 | p = swap_info[type]; |
1da177e4 LT |
514 | if (!(p->flags & SWP_USED)) |
515 | goto bad_device; | |
516 | offset = swp_offset(entry); | |
517 | if (offset >= p->max) | |
518 | goto bad_offset; | |
519 | if (!p->swap_map[offset]) | |
520 | goto bad_free; | |
5d337b91 | 521 | spin_lock(&swap_lock); |
1da177e4 LT |
522 | return p; |
523 | ||
524 | bad_free: | |
525 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val); | |
526 | goto out; | |
527 | bad_offset: | |
528 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val); | |
529 | goto out; | |
530 | bad_device: | |
531 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val); | |
532 | goto out; | |
533 | bad_nofile: | |
534 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val); | |
535 | out: | |
536 | return NULL; | |
886bb7e9 | 537 | } |
1da177e4 | 538 | |
8d69aaee HD |
539 | static unsigned char swap_entry_free(struct swap_info_struct *p, |
540 | swp_entry_t entry, unsigned char usage) | |
1da177e4 | 541 | { |
253d553b | 542 | unsigned long offset = swp_offset(entry); |
8d69aaee HD |
543 | unsigned char count; |
544 | unsigned char has_cache; | |
355cfa73 | 545 | |
253d553b HD |
546 | count = p->swap_map[offset]; |
547 | has_cache = count & SWAP_HAS_CACHE; | |
548 | count &= ~SWAP_HAS_CACHE; | |
355cfa73 | 549 | |
253d553b | 550 | if (usage == SWAP_HAS_CACHE) { |
355cfa73 | 551 | VM_BUG_ON(!has_cache); |
253d553b | 552 | has_cache = 0; |
aaa46865 HD |
553 | } else if (count == SWAP_MAP_SHMEM) { |
554 | /* | |
555 | * Or we could insist on shmem.c using a special | |
556 | * swap_shmem_free() and free_shmem_swap_and_cache()... | |
557 | */ | |
558 | count = 0; | |
570a335b HD |
559 | } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { |
560 | if (count == COUNT_CONTINUED) { | |
561 | if (swap_count_continued(p, offset, count)) | |
562 | count = SWAP_MAP_MAX | COUNT_CONTINUED; | |
563 | else | |
564 | count = SWAP_MAP_MAX; | |
565 | } else | |
566 | count--; | |
567 | } | |
253d553b HD |
568 | |
569 | if (!count) | |
570 | mem_cgroup_uncharge_swap(entry); | |
571 | ||
572 | usage = count | has_cache; | |
573 | p->swap_map[offset] = usage; | |
355cfa73 | 574 | |
355cfa73 | 575 | /* free if no reference */ |
253d553b | 576 | if (!usage) { |
355cfa73 KH |
577 | if (offset < p->lowest_bit) |
578 | p->lowest_bit = offset; | |
579 | if (offset > p->highest_bit) | |
580 | p->highest_bit = offset; | |
efa90a98 HD |
581 | if (swap_list.next >= 0 && |
582 | p->prio > swap_info[swap_list.next]->prio) | |
583 | swap_list.next = p->type; | |
355cfa73 KH |
584 | nr_swap_pages++; |
585 | p->inuse_pages--; | |
1da177e4 | 586 | } |
253d553b HD |
587 | |
588 | return usage; | |
1da177e4 LT |
589 | } |
590 | ||
591 | /* | |
592 | * Caller has made sure that the swapdevice corresponding to entry | |
593 | * is still around or has not been recycled. | |
594 | */ | |
595 | void swap_free(swp_entry_t entry) | |
596 | { | |
73c34b6a | 597 | struct swap_info_struct *p; |
1da177e4 LT |
598 | |
599 | p = swap_info_get(entry); | |
600 | if (p) { | |
253d553b | 601 | swap_entry_free(p, entry, 1); |
5d337b91 | 602 | spin_unlock(&swap_lock); |
1da177e4 LT |
603 | } |
604 | } | |
605 | ||
cb4b86ba KH |
606 | /* |
607 | * Called after dropping swapcache to decrease refcnt to swap entries. | |
608 | */ | |
609 | void swapcache_free(swp_entry_t entry, struct page *page) | |
610 | { | |
355cfa73 | 611 | struct swap_info_struct *p; |
8d69aaee | 612 | unsigned char count; |
355cfa73 | 613 | |
355cfa73 KH |
614 | p = swap_info_get(entry); |
615 | if (p) { | |
253d553b HD |
616 | count = swap_entry_free(p, entry, SWAP_HAS_CACHE); |
617 | if (page) | |
618 | mem_cgroup_uncharge_swapcache(page, entry, count != 0); | |
355cfa73 KH |
619 | spin_unlock(&swap_lock); |
620 | } | |
cb4b86ba KH |
621 | } |
622 | ||
1da177e4 | 623 | /* |
c475a8ab | 624 | * How many references to page are currently swapped out? |
570a335b HD |
625 | * This does not give an exact answer when swap count is continued, |
626 | * but does include the high COUNT_CONTINUED flag to allow for that. | |
1da177e4 | 627 | */ |
c475a8ab | 628 | static inline int page_swapcount(struct page *page) |
1da177e4 | 629 | { |
c475a8ab HD |
630 | int count = 0; |
631 | struct swap_info_struct *p; | |
1da177e4 LT |
632 | swp_entry_t entry; |
633 | ||
4c21e2f2 | 634 | entry.val = page_private(page); |
1da177e4 LT |
635 | p = swap_info_get(entry); |
636 | if (p) { | |
355cfa73 | 637 | count = swap_count(p->swap_map[swp_offset(entry)]); |
5d337b91 | 638 | spin_unlock(&swap_lock); |
1da177e4 | 639 | } |
c475a8ab | 640 | return count; |
1da177e4 LT |
641 | } |
642 | ||
643 | /* | |
7b1fe597 HD |
644 | * We can write to an anon page without COW if there are no other references |
645 | * to it. And as a side-effect, free up its swap: because the old content | |
646 | * on disk will never be read, and seeking back there to write new content | |
647 | * later would only waste time away from clustering. | |
1da177e4 | 648 | */ |
7b1fe597 | 649 | int reuse_swap_page(struct page *page) |
1da177e4 | 650 | { |
c475a8ab HD |
651 | int count; |
652 | ||
51726b12 | 653 | VM_BUG_ON(!PageLocked(page)); |
5ad64688 HD |
654 | if (unlikely(PageKsm(page))) |
655 | return 0; | |
c475a8ab | 656 | count = page_mapcount(page); |
7b1fe597 | 657 | if (count <= 1 && PageSwapCache(page)) { |
c475a8ab | 658 | count += page_swapcount(page); |
7b1fe597 HD |
659 | if (count == 1 && !PageWriteback(page)) { |
660 | delete_from_swap_cache(page); | |
661 | SetPageDirty(page); | |
662 | } | |
663 | } | |
5ad64688 | 664 | return count <= 1; |
1da177e4 LT |
665 | } |
666 | ||
667 | /* | |
a2c43eed HD |
668 | * If swap is getting full, or if there are no more mappings of this page, |
669 | * then try_to_free_swap is called to free its swap space. | |
1da177e4 | 670 | */ |
a2c43eed | 671 | int try_to_free_swap(struct page *page) |
1da177e4 | 672 | { |
51726b12 | 673 | VM_BUG_ON(!PageLocked(page)); |
1da177e4 LT |
674 | |
675 | if (!PageSwapCache(page)) | |
676 | return 0; | |
677 | if (PageWriteback(page)) | |
678 | return 0; | |
a2c43eed | 679 | if (page_swapcount(page)) |
1da177e4 LT |
680 | return 0; |
681 | ||
a2c43eed HD |
682 | delete_from_swap_cache(page); |
683 | SetPageDirty(page); | |
684 | return 1; | |
68a22394 RR |
685 | } |
686 | ||
1da177e4 LT |
687 | /* |
688 | * Free the swap entry like above, but also try to | |
689 | * free the page cache entry if it is the last user. | |
690 | */ | |
2509ef26 | 691 | int free_swap_and_cache(swp_entry_t entry) |
1da177e4 | 692 | { |
2509ef26 | 693 | struct swap_info_struct *p; |
1da177e4 LT |
694 | struct page *page = NULL; |
695 | ||
a7420aa5 | 696 | if (non_swap_entry(entry)) |
2509ef26 | 697 | return 1; |
0697212a | 698 | |
1da177e4 LT |
699 | p = swap_info_get(entry); |
700 | if (p) { | |
253d553b | 701 | if (swap_entry_free(p, entry, 1) == SWAP_HAS_CACHE) { |
93fac704 | 702 | page = find_get_page(&swapper_space, entry.val); |
8413ac9d | 703 | if (page && !trylock_page(page)) { |
93fac704 NP |
704 | page_cache_release(page); |
705 | page = NULL; | |
706 | } | |
707 | } | |
5d337b91 | 708 | spin_unlock(&swap_lock); |
1da177e4 LT |
709 | } |
710 | if (page) { | |
a2c43eed HD |
711 | /* |
712 | * Not mapped elsewhere, or swap space full? Free it! | |
713 | * Also recheck PageSwapCache now page is locked (above). | |
714 | */ | |
93fac704 | 715 | if (PageSwapCache(page) && !PageWriteback(page) && |
a2c43eed | 716 | (!page_mapped(page) || vm_swap_full())) { |
1da177e4 LT |
717 | delete_from_swap_cache(page); |
718 | SetPageDirty(page); | |
719 | } | |
720 | unlock_page(page); | |
721 | page_cache_release(page); | |
722 | } | |
2509ef26 | 723 | return p != NULL; |
1da177e4 LT |
724 | } |
725 | ||
b0cb1a19 | 726 | #ifdef CONFIG_HIBERNATION |
f577eb30 | 727 | /* |
915bae9e | 728 | * Find the swap type that corresponds to given device (if any). |
f577eb30 | 729 | * |
915bae9e RW |
730 | * @offset - number of the PAGE_SIZE-sized block of the device, starting |
731 | * from 0, in which the swap header is expected to be located. | |
732 | * | |
733 | * This is needed for the suspend to disk (aka swsusp). | |
f577eb30 | 734 | */ |
7bf23687 | 735 | int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) |
f577eb30 | 736 | { |
915bae9e | 737 | struct block_device *bdev = NULL; |
efa90a98 | 738 | int type; |
f577eb30 | 739 | |
915bae9e RW |
740 | if (device) |
741 | bdev = bdget(device); | |
742 | ||
f577eb30 | 743 | spin_lock(&swap_lock); |
efa90a98 HD |
744 | for (type = 0; type < nr_swapfiles; type++) { |
745 | struct swap_info_struct *sis = swap_info[type]; | |
f577eb30 | 746 | |
915bae9e | 747 | if (!(sis->flags & SWP_WRITEOK)) |
f577eb30 | 748 | continue; |
b6b5bce3 | 749 | |
915bae9e | 750 | if (!bdev) { |
7bf23687 | 751 | if (bdev_p) |
dddac6a7 | 752 | *bdev_p = bdgrab(sis->bdev); |
7bf23687 | 753 | |
6e1819d6 | 754 | spin_unlock(&swap_lock); |
efa90a98 | 755 | return type; |
6e1819d6 | 756 | } |
915bae9e | 757 | if (bdev == sis->bdev) { |
9625a5f2 | 758 | struct swap_extent *se = &sis->first_swap_extent; |
915bae9e | 759 | |
915bae9e | 760 | if (se->start_block == offset) { |
7bf23687 | 761 | if (bdev_p) |
dddac6a7 | 762 | *bdev_p = bdgrab(sis->bdev); |
7bf23687 | 763 | |
915bae9e RW |
764 | spin_unlock(&swap_lock); |
765 | bdput(bdev); | |
efa90a98 | 766 | return type; |
915bae9e | 767 | } |
f577eb30 RW |
768 | } |
769 | } | |
770 | spin_unlock(&swap_lock); | |
915bae9e RW |
771 | if (bdev) |
772 | bdput(bdev); | |
773 | ||
f577eb30 RW |
774 | return -ENODEV; |
775 | } | |
776 | ||
73c34b6a HD |
777 | /* |
778 | * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev | |
779 | * corresponding to given index in swap_info (swap type). | |
780 | */ | |
781 | sector_t swapdev_block(int type, pgoff_t offset) | |
782 | { | |
783 | struct block_device *bdev; | |
784 | ||
785 | if ((unsigned int)type >= nr_swapfiles) | |
786 | return 0; | |
787 | if (!(swap_info[type]->flags & SWP_WRITEOK)) | |
788 | return 0; | |
d4906e1a | 789 | return map_swap_entry(swp_entry(type, offset), &bdev); |
73c34b6a HD |
790 | } |
791 | ||
f577eb30 RW |
792 | /* |
793 | * Return either the total number of swap pages of given type, or the number | |
794 | * of free pages of that type (depending on @free) | |
795 | * | |
796 | * This is needed for software suspend | |
797 | */ | |
798 | unsigned int count_swap_pages(int type, int free) | |
799 | { | |
800 | unsigned int n = 0; | |
801 | ||
efa90a98 HD |
802 | spin_lock(&swap_lock); |
803 | if ((unsigned int)type < nr_swapfiles) { | |
804 | struct swap_info_struct *sis = swap_info[type]; | |
805 | ||
806 | if (sis->flags & SWP_WRITEOK) { | |
807 | n = sis->pages; | |
f577eb30 | 808 | if (free) |
efa90a98 | 809 | n -= sis->inuse_pages; |
f577eb30 | 810 | } |
f577eb30 | 811 | } |
efa90a98 | 812 | spin_unlock(&swap_lock); |
f577eb30 RW |
813 | return n; |
814 | } | |
73c34b6a | 815 | #endif /* CONFIG_HIBERNATION */ |
f577eb30 | 816 | |
1da177e4 | 817 | /* |
72866f6f HD |
818 | * No need to decide whether this PTE shares the swap entry with others, |
819 | * just let do_wp_page work it out if a write is requested later - to | |
820 | * force COW, vm_page_prot omits write permission from any private vma. | |
1da177e4 | 821 | */ |
044d66c1 | 822 | static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
1da177e4 LT |
823 | unsigned long addr, swp_entry_t entry, struct page *page) |
824 | { | |
7a81b88c | 825 | struct mem_cgroup *ptr = NULL; |
044d66c1 HD |
826 | spinlock_t *ptl; |
827 | pte_t *pte; | |
828 | int ret = 1; | |
829 | ||
85d9fc89 | 830 | if (mem_cgroup_try_charge_swapin(vma->vm_mm, page, GFP_KERNEL, &ptr)) { |
044d66c1 | 831 | ret = -ENOMEM; |
85d9fc89 KH |
832 | goto out_nolock; |
833 | } | |
044d66c1 HD |
834 | |
835 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); | |
836 | if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) { | |
837 | if (ret > 0) | |
7a81b88c | 838 | mem_cgroup_cancel_charge_swapin(ptr); |
044d66c1 HD |
839 | ret = 0; |
840 | goto out; | |
841 | } | |
8a9f3ccd | 842 | |
b084d435 | 843 | dec_mm_counter(vma->vm_mm, MM_SWAPENTS); |
d559db08 | 844 | inc_mm_counter(vma->vm_mm, MM_ANONPAGES); |
1da177e4 LT |
845 | get_page(page); |
846 | set_pte_at(vma->vm_mm, addr, pte, | |
847 | pte_mkold(mk_pte(page, vma->vm_page_prot))); | |
848 | page_add_anon_rmap(page, vma, addr); | |
7a81b88c | 849 | mem_cgroup_commit_charge_swapin(page, ptr); |
1da177e4 LT |
850 | swap_free(entry); |
851 | /* | |
852 | * Move the page to the active list so it is not | |
853 | * immediately swapped out again after swapon. | |
854 | */ | |
855 | activate_page(page); | |
044d66c1 HD |
856 | out: |
857 | pte_unmap_unlock(pte, ptl); | |
85d9fc89 | 858 | out_nolock: |
044d66c1 | 859 | return ret; |
1da177e4 LT |
860 | } |
861 | ||
862 | static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, | |
863 | unsigned long addr, unsigned long end, | |
864 | swp_entry_t entry, struct page *page) | |
865 | { | |
1da177e4 | 866 | pte_t swp_pte = swp_entry_to_pte(entry); |
705e87c0 | 867 | pte_t *pte; |
8a9f3ccd | 868 | int ret = 0; |
1da177e4 | 869 | |
044d66c1 HD |
870 | /* |
871 | * We don't actually need pte lock while scanning for swp_pte: since | |
872 | * we hold page lock and mmap_sem, swp_pte cannot be inserted into the | |
873 | * page table while we're scanning; though it could get zapped, and on | |
874 | * some architectures (e.g. x86_32 with PAE) we might catch a glimpse | |
875 | * of unmatched parts which look like swp_pte, so unuse_pte must | |
876 | * recheck under pte lock. Scanning without pte lock lets it be | |
877 | * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE. | |
878 | */ | |
879 | pte = pte_offset_map(pmd, addr); | |
1da177e4 LT |
880 | do { |
881 | /* | |
882 | * swapoff spends a _lot_ of time in this loop! | |
883 | * Test inline before going to call unuse_pte. | |
884 | */ | |
885 | if (unlikely(pte_same(*pte, swp_pte))) { | |
044d66c1 HD |
886 | pte_unmap(pte); |
887 | ret = unuse_pte(vma, pmd, addr, entry, page); | |
888 | if (ret) | |
889 | goto out; | |
890 | pte = pte_offset_map(pmd, addr); | |
1da177e4 LT |
891 | } |
892 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
044d66c1 HD |
893 | pte_unmap(pte - 1); |
894 | out: | |
8a9f3ccd | 895 | return ret; |
1da177e4 LT |
896 | } |
897 | ||
898 | static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, | |
899 | unsigned long addr, unsigned long end, | |
900 | swp_entry_t entry, struct page *page) | |
901 | { | |
902 | pmd_t *pmd; | |
903 | unsigned long next; | |
8a9f3ccd | 904 | int ret; |
1da177e4 LT |
905 | |
906 | pmd = pmd_offset(pud, addr); | |
907 | do { | |
908 | next = pmd_addr_end(addr, end); | |
909 | if (pmd_none_or_clear_bad(pmd)) | |
910 | continue; | |
8a9f3ccd BS |
911 | ret = unuse_pte_range(vma, pmd, addr, next, entry, page); |
912 | if (ret) | |
913 | return ret; | |
1da177e4 LT |
914 | } while (pmd++, addr = next, addr != end); |
915 | return 0; | |
916 | } | |
917 | ||
918 | static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd, | |
919 | unsigned long addr, unsigned long end, | |
920 | swp_entry_t entry, struct page *page) | |
921 | { | |
922 | pud_t *pud; | |
923 | unsigned long next; | |
8a9f3ccd | 924 | int ret; |
1da177e4 LT |
925 | |
926 | pud = pud_offset(pgd, addr); | |
927 | do { | |
928 | next = pud_addr_end(addr, end); | |
929 | if (pud_none_or_clear_bad(pud)) | |
930 | continue; | |
8a9f3ccd BS |
931 | ret = unuse_pmd_range(vma, pud, addr, next, entry, page); |
932 | if (ret) | |
933 | return ret; | |
1da177e4 LT |
934 | } while (pud++, addr = next, addr != end); |
935 | return 0; | |
936 | } | |
937 | ||
938 | static int unuse_vma(struct vm_area_struct *vma, | |
939 | swp_entry_t entry, struct page *page) | |
940 | { | |
941 | pgd_t *pgd; | |
942 | unsigned long addr, end, next; | |
8a9f3ccd | 943 | int ret; |
1da177e4 | 944 | |
3ca7b3c5 | 945 | if (page_anon_vma(page)) { |
1da177e4 LT |
946 | addr = page_address_in_vma(page, vma); |
947 | if (addr == -EFAULT) | |
948 | return 0; | |
949 | else | |
950 | end = addr + PAGE_SIZE; | |
951 | } else { | |
952 | addr = vma->vm_start; | |
953 | end = vma->vm_end; | |
954 | } | |
955 | ||
956 | pgd = pgd_offset(vma->vm_mm, addr); | |
957 | do { | |
958 | next = pgd_addr_end(addr, end); | |
959 | if (pgd_none_or_clear_bad(pgd)) | |
960 | continue; | |
8a9f3ccd BS |
961 | ret = unuse_pud_range(vma, pgd, addr, next, entry, page); |
962 | if (ret) | |
963 | return ret; | |
1da177e4 LT |
964 | } while (pgd++, addr = next, addr != end); |
965 | return 0; | |
966 | } | |
967 | ||
968 | static int unuse_mm(struct mm_struct *mm, | |
969 | swp_entry_t entry, struct page *page) | |
970 | { | |
971 | struct vm_area_struct *vma; | |
8a9f3ccd | 972 | int ret = 0; |
1da177e4 LT |
973 | |
974 | if (!down_read_trylock(&mm->mmap_sem)) { | |
975 | /* | |
7d03431c FLVC |
976 | * Activate page so shrink_inactive_list is unlikely to unmap |
977 | * its ptes while lock is dropped, so swapoff can make progress. | |
1da177e4 | 978 | */ |
c475a8ab | 979 | activate_page(page); |
1da177e4 LT |
980 | unlock_page(page); |
981 | down_read(&mm->mmap_sem); | |
982 | lock_page(page); | |
983 | } | |
1da177e4 | 984 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
8a9f3ccd | 985 | if (vma->anon_vma && (ret = unuse_vma(vma, entry, page))) |
1da177e4 LT |
986 | break; |
987 | } | |
1da177e4 | 988 | up_read(&mm->mmap_sem); |
8a9f3ccd | 989 | return (ret < 0)? ret: 0; |
1da177e4 LT |
990 | } |
991 | ||
992 | /* | |
993 | * Scan swap_map from current position to next entry still in use. | |
994 | * Recycle to start on reaching the end, returning 0 when empty. | |
995 | */ | |
6eb396dc HD |
996 | static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
997 | unsigned int prev) | |
1da177e4 | 998 | { |
6eb396dc HD |
999 | unsigned int max = si->max; |
1000 | unsigned int i = prev; | |
8d69aaee | 1001 | unsigned char count; |
1da177e4 LT |
1002 | |
1003 | /* | |
5d337b91 | 1004 | * No need for swap_lock here: we're just looking |
1da177e4 LT |
1005 | * for whether an entry is in use, not modifying it; false |
1006 | * hits are okay, and sys_swapoff() has already prevented new | |
5d337b91 | 1007 | * allocations from this area (while holding swap_lock). |
1da177e4 LT |
1008 | */ |
1009 | for (;;) { | |
1010 | if (++i >= max) { | |
1011 | if (!prev) { | |
1012 | i = 0; | |
1013 | break; | |
1014 | } | |
1015 | /* | |
1016 | * No entries in use at top of swap_map, | |
1017 | * loop back to start and recheck there. | |
1018 | */ | |
1019 | max = prev + 1; | |
1020 | prev = 0; | |
1021 | i = 1; | |
1022 | } | |
1023 | count = si->swap_map[i]; | |
355cfa73 | 1024 | if (count && swap_count(count) != SWAP_MAP_BAD) |
1da177e4 LT |
1025 | break; |
1026 | } | |
1027 | return i; | |
1028 | } | |
1029 | ||
1030 | /* | |
1031 | * We completely avoid races by reading each swap page in advance, | |
1032 | * and then search for the process using it. All the necessary | |
1033 | * page table adjustments can then be made atomically. | |
1034 | */ | |
1035 | static int try_to_unuse(unsigned int type) | |
1036 | { | |
efa90a98 | 1037 | struct swap_info_struct *si = swap_info[type]; |
1da177e4 | 1038 | struct mm_struct *start_mm; |
8d69aaee HD |
1039 | unsigned char *swap_map; |
1040 | unsigned char swcount; | |
1da177e4 LT |
1041 | struct page *page; |
1042 | swp_entry_t entry; | |
6eb396dc | 1043 | unsigned int i = 0; |
1da177e4 | 1044 | int retval = 0; |
1da177e4 LT |
1045 | |
1046 | /* | |
1047 | * When searching mms for an entry, a good strategy is to | |
1048 | * start at the first mm we freed the previous entry from | |
1049 | * (though actually we don't notice whether we or coincidence | |
1050 | * freed the entry). Initialize this start_mm with a hold. | |
1051 | * | |
1052 | * A simpler strategy would be to start at the last mm we | |
1053 | * freed the previous entry from; but that would take less | |
1054 | * advantage of mmlist ordering, which clusters forked mms | |
1055 | * together, child after parent. If we race with dup_mmap(), we | |
1056 | * prefer to resolve parent before child, lest we miss entries | |
1057 | * duplicated after we scanned child: using last mm would invert | |
570a335b | 1058 | * that. |
1da177e4 LT |
1059 | */ |
1060 | start_mm = &init_mm; | |
1061 | atomic_inc(&init_mm.mm_users); | |
1062 | ||
1063 | /* | |
1064 | * Keep on scanning until all entries have gone. Usually, | |
1065 | * one pass through swap_map is enough, but not necessarily: | |
1066 | * there are races when an instance of an entry might be missed. | |
1067 | */ | |
1068 | while ((i = find_next_to_unuse(si, i)) != 0) { | |
1069 | if (signal_pending(current)) { | |
1070 | retval = -EINTR; | |
1071 | break; | |
1072 | } | |
1073 | ||
886bb7e9 | 1074 | /* |
1da177e4 LT |
1075 | * Get a page for the entry, using the existing swap |
1076 | * cache page if there is one. Otherwise, get a clean | |
886bb7e9 | 1077 | * page and read the swap into it. |
1da177e4 LT |
1078 | */ |
1079 | swap_map = &si->swap_map[i]; | |
1080 | entry = swp_entry(type, i); | |
02098fea HD |
1081 | page = read_swap_cache_async(entry, |
1082 | GFP_HIGHUSER_MOVABLE, NULL, 0); | |
1da177e4 LT |
1083 | if (!page) { |
1084 | /* | |
1085 | * Either swap_duplicate() failed because entry | |
1086 | * has been freed independently, and will not be | |
1087 | * reused since sys_swapoff() already disabled | |
1088 | * allocation from here, or alloc_page() failed. | |
1089 | */ | |
1090 | if (!*swap_map) | |
1091 | continue; | |
1092 | retval = -ENOMEM; | |
1093 | break; | |
1094 | } | |
1095 | ||
1096 | /* | |
1097 | * Don't hold on to start_mm if it looks like exiting. | |
1098 | */ | |
1099 | if (atomic_read(&start_mm->mm_users) == 1) { | |
1100 | mmput(start_mm); | |
1101 | start_mm = &init_mm; | |
1102 | atomic_inc(&init_mm.mm_users); | |
1103 | } | |
1104 | ||
1105 | /* | |
1106 | * Wait for and lock page. When do_swap_page races with | |
1107 | * try_to_unuse, do_swap_page can handle the fault much | |
1108 | * faster than try_to_unuse can locate the entry. This | |
1109 | * apparently redundant "wait_on_page_locked" lets try_to_unuse | |
1110 | * defer to do_swap_page in such a case - in some tests, | |
1111 | * do_swap_page and try_to_unuse repeatedly compete. | |
1112 | */ | |
1113 | wait_on_page_locked(page); | |
1114 | wait_on_page_writeback(page); | |
1115 | lock_page(page); | |
1116 | wait_on_page_writeback(page); | |
1117 | ||
1118 | /* | |
1119 | * Remove all references to entry. | |
1da177e4 | 1120 | */ |
1da177e4 | 1121 | swcount = *swap_map; |
aaa46865 HD |
1122 | if (swap_count(swcount) == SWAP_MAP_SHMEM) { |
1123 | retval = shmem_unuse(entry, page); | |
1124 | /* page has already been unlocked and released */ | |
1125 | if (retval < 0) | |
1126 | break; | |
1127 | continue; | |
1da177e4 | 1128 | } |
aaa46865 HD |
1129 | if (swap_count(swcount) && start_mm != &init_mm) |
1130 | retval = unuse_mm(start_mm, entry, page); | |
1131 | ||
355cfa73 | 1132 | if (swap_count(*swap_map)) { |
1da177e4 LT |
1133 | int set_start_mm = (*swap_map >= swcount); |
1134 | struct list_head *p = &start_mm->mmlist; | |
1135 | struct mm_struct *new_start_mm = start_mm; | |
1136 | struct mm_struct *prev_mm = start_mm; | |
1137 | struct mm_struct *mm; | |
1138 | ||
1139 | atomic_inc(&new_start_mm->mm_users); | |
1140 | atomic_inc(&prev_mm->mm_users); | |
1141 | spin_lock(&mmlist_lock); | |
aaa46865 | 1142 | while (swap_count(*swap_map) && !retval && |
1da177e4 LT |
1143 | (p = p->next) != &start_mm->mmlist) { |
1144 | mm = list_entry(p, struct mm_struct, mmlist); | |
70af7c5c | 1145 | if (!atomic_inc_not_zero(&mm->mm_users)) |
1da177e4 | 1146 | continue; |
1da177e4 LT |
1147 | spin_unlock(&mmlist_lock); |
1148 | mmput(prev_mm); | |
1149 | prev_mm = mm; | |
1150 | ||
1151 | cond_resched(); | |
1152 | ||
1153 | swcount = *swap_map; | |
355cfa73 | 1154 | if (!swap_count(swcount)) /* any usage ? */ |
1da177e4 | 1155 | ; |
aaa46865 | 1156 | else if (mm == &init_mm) |
1da177e4 | 1157 | set_start_mm = 1; |
aaa46865 | 1158 | else |
1da177e4 | 1159 | retval = unuse_mm(mm, entry, page); |
355cfa73 | 1160 | |
32c5fc10 | 1161 | if (set_start_mm && *swap_map < swcount) { |
1da177e4 LT |
1162 | mmput(new_start_mm); |
1163 | atomic_inc(&mm->mm_users); | |
1164 | new_start_mm = mm; | |
1165 | set_start_mm = 0; | |
1166 | } | |
1167 | spin_lock(&mmlist_lock); | |
1168 | } | |
1169 | spin_unlock(&mmlist_lock); | |
1170 | mmput(prev_mm); | |
1171 | mmput(start_mm); | |
1172 | start_mm = new_start_mm; | |
1173 | } | |
1174 | if (retval) { | |
1175 | unlock_page(page); | |
1176 | page_cache_release(page); | |
1177 | break; | |
1178 | } | |
1179 | ||
1da177e4 LT |
1180 | /* |
1181 | * If a reference remains (rare), we would like to leave | |
1182 | * the page in the swap cache; but try_to_unmap could | |
1183 | * then re-duplicate the entry once we drop page lock, | |
1184 | * so we might loop indefinitely; also, that page could | |
1185 | * not be swapped out to other storage meanwhile. So: | |
1186 | * delete from cache even if there's another reference, | |
1187 | * after ensuring that the data has been saved to disk - | |
1188 | * since if the reference remains (rarer), it will be | |
1189 | * read from disk into another page. Splitting into two | |
1190 | * pages would be incorrect if swap supported "shared | |
1191 | * private" pages, but they are handled by tmpfs files. | |
5ad64688 HD |
1192 | * |
1193 | * Given how unuse_vma() targets one particular offset | |
1194 | * in an anon_vma, once the anon_vma has been determined, | |
1195 | * this splitting happens to be just what is needed to | |
1196 | * handle where KSM pages have been swapped out: re-reading | |
1197 | * is unnecessarily slow, but we can fix that later on. | |
1da177e4 | 1198 | */ |
355cfa73 KH |
1199 | if (swap_count(*swap_map) && |
1200 | PageDirty(page) && PageSwapCache(page)) { | |
1da177e4 LT |
1201 | struct writeback_control wbc = { |
1202 | .sync_mode = WB_SYNC_NONE, | |
1203 | }; | |
1204 | ||
1205 | swap_writepage(page, &wbc); | |
1206 | lock_page(page); | |
1207 | wait_on_page_writeback(page); | |
1208 | } | |
68bdc8d6 HD |
1209 | |
1210 | /* | |
1211 | * It is conceivable that a racing task removed this page from | |
1212 | * swap cache just before we acquired the page lock at the top, | |
1213 | * or while we dropped it in unuse_mm(). The page might even | |
1214 | * be back in swap cache on another swap area: that we must not | |
1215 | * delete, since it may not have been written out to swap yet. | |
1216 | */ | |
1217 | if (PageSwapCache(page) && | |
1218 | likely(page_private(page) == entry.val)) | |
2e0e26c7 | 1219 | delete_from_swap_cache(page); |
1da177e4 LT |
1220 | |
1221 | /* | |
1222 | * So we could skip searching mms once swap count went | |
1223 | * to 1, we did not mark any present ptes as dirty: must | |
2706a1b8 | 1224 | * mark page dirty so shrink_page_list will preserve it. |
1da177e4 LT |
1225 | */ |
1226 | SetPageDirty(page); | |
1227 | unlock_page(page); | |
1228 | page_cache_release(page); | |
1229 | ||
1230 | /* | |
1231 | * Make sure that we aren't completely killing | |
1232 | * interactive performance. | |
1233 | */ | |
1234 | cond_resched(); | |
1235 | } | |
1236 | ||
1237 | mmput(start_mm); | |
1da177e4 LT |
1238 | return retval; |
1239 | } | |
1240 | ||
1241 | /* | |
5d337b91 HD |
1242 | * After a successful try_to_unuse, if no swap is now in use, we know |
1243 | * we can empty the mmlist. swap_lock must be held on entry and exit. | |
1244 | * Note that mmlist_lock nests inside swap_lock, and an mm must be | |
1da177e4 LT |
1245 | * added to the mmlist just after page_duplicate - before would be racy. |
1246 | */ | |
1247 | static void drain_mmlist(void) | |
1248 | { | |
1249 | struct list_head *p, *next; | |
efa90a98 | 1250 | unsigned int type; |
1da177e4 | 1251 | |
efa90a98 HD |
1252 | for (type = 0; type < nr_swapfiles; type++) |
1253 | if (swap_info[type]->inuse_pages) | |
1da177e4 LT |
1254 | return; |
1255 | spin_lock(&mmlist_lock); | |
1256 | list_for_each_safe(p, next, &init_mm.mmlist) | |
1257 | list_del_init(p); | |
1258 | spin_unlock(&mmlist_lock); | |
1259 | } | |
1260 | ||
1261 | /* | |
1262 | * Use this swapdev's extent info to locate the (PAGE_SIZE) block which | |
d4906e1a LS |
1263 | * corresponds to page offset for the specified swap entry. |
1264 | * Note that the type of this function is sector_t, but it returns page offset | |
1265 | * into the bdev, not sector offset. | |
1da177e4 | 1266 | */ |
d4906e1a | 1267 | static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev) |
1da177e4 | 1268 | { |
f29ad6a9 HD |
1269 | struct swap_info_struct *sis; |
1270 | struct swap_extent *start_se; | |
1271 | struct swap_extent *se; | |
1272 | pgoff_t offset; | |
1273 | ||
efa90a98 | 1274 | sis = swap_info[swp_type(entry)]; |
f29ad6a9 HD |
1275 | *bdev = sis->bdev; |
1276 | ||
1277 | offset = swp_offset(entry); | |
1278 | start_se = sis->curr_swap_extent; | |
1279 | se = start_se; | |
1da177e4 LT |
1280 | |
1281 | for ( ; ; ) { | |
1282 | struct list_head *lh; | |
1283 | ||
1284 | if (se->start_page <= offset && | |
1285 | offset < (se->start_page + se->nr_pages)) { | |
1286 | return se->start_block + (offset - se->start_page); | |
1287 | } | |
11d31886 | 1288 | lh = se->list.next; |
1da177e4 LT |
1289 | se = list_entry(lh, struct swap_extent, list); |
1290 | sis->curr_swap_extent = se; | |
1291 | BUG_ON(se == start_se); /* It *must* be present */ | |
1292 | } | |
1293 | } | |
1294 | ||
d4906e1a LS |
1295 | /* |
1296 | * Returns the page offset into bdev for the specified page's swap entry. | |
1297 | */ | |
1298 | sector_t map_swap_page(struct page *page, struct block_device **bdev) | |
1299 | { | |
1300 | swp_entry_t entry; | |
1301 | entry.val = page_private(page); | |
1302 | return map_swap_entry(entry, bdev); | |
1303 | } | |
1304 | ||
1da177e4 LT |
1305 | /* |
1306 | * Free all of a swapdev's extent information | |
1307 | */ | |
1308 | static void destroy_swap_extents(struct swap_info_struct *sis) | |
1309 | { | |
9625a5f2 | 1310 | while (!list_empty(&sis->first_swap_extent.list)) { |
1da177e4 LT |
1311 | struct swap_extent *se; |
1312 | ||
9625a5f2 | 1313 | se = list_entry(sis->first_swap_extent.list.next, |
1da177e4 LT |
1314 | struct swap_extent, list); |
1315 | list_del(&se->list); | |
1316 | kfree(se); | |
1317 | } | |
1da177e4 LT |
1318 | } |
1319 | ||
1320 | /* | |
1321 | * Add a block range (and the corresponding page range) into this swapdev's | |
11d31886 | 1322 | * extent list. The extent list is kept sorted in page order. |
1da177e4 | 1323 | * |
11d31886 | 1324 | * This function rather assumes that it is called in ascending page order. |
1da177e4 LT |
1325 | */ |
1326 | static int | |
1327 | add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, | |
1328 | unsigned long nr_pages, sector_t start_block) | |
1329 | { | |
1330 | struct swap_extent *se; | |
1331 | struct swap_extent *new_se; | |
1332 | struct list_head *lh; | |
1333 | ||
9625a5f2 HD |
1334 | if (start_page == 0) { |
1335 | se = &sis->first_swap_extent; | |
1336 | sis->curr_swap_extent = se; | |
1337 | se->start_page = 0; | |
1338 | se->nr_pages = nr_pages; | |
1339 | se->start_block = start_block; | |
1340 | return 1; | |
1341 | } else { | |
1342 | lh = sis->first_swap_extent.list.prev; /* Highest extent */ | |
1da177e4 | 1343 | se = list_entry(lh, struct swap_extent, list); |
11d31886 HD |
1344 | BUG_ON(se->start_page + se->nr_pages != start_page); |
1345 | if (se->start_block + se->nr_pages == start_block) { | |
1da177e4 LT |
1346 | /* Merge it */ |
1347 | se->nr_pages += nr_pages; | |
1348 | return 0; | |
1349 | } | |
1da177e4 LT |
1350 | } |
1351 | ||
1352 | /* | |
1353 | * No merge. Insert a new extent, preserving ordering. | |
1354 | */ | |
1355 | new_se = kmalloc(sizeof(*se), GFP_KERNEL); | |
1356 | if (new_se == NULL) | |
1357 | return -ENOMEM; | |
1358 | new_se->start_page = start_page; | |
1359 | new_se->nr_pages = nr_pages; | |
1360 | new_se->start_block = start_block; | |
1361 | ||
9625a5f2 | 1362 | list_add_tail(&new_se->list, &sis->first_swap_extent.list); |
53092a74 | 1363 | return 1; |
1da177e4 LT |
1364 | } |
1365 | ||
1366 | /* | |
1367 | * A `swap extent' is a simple thing which maps a contiguous range of pages | |
1368 | * onto a contiguous range of disk blocks. An ordered list of swap extents | |
1369 | * is built at swapon time and is then used at swap_writepage/swap_readpage | |
1370 | * time for locating where on disk a page belongs. | |
1371 | * | |
1372 | * If the swapfile is an S_ISBLK block device, a single extent is installed. | |
1373 | * This is done so that the main operating code can treat S_ISBLK and S_ISREG | |
1374 | * swap files identically. | |
1375 | * | |
1376 | * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap | |
1377 | * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK | |
1378 | * swapfiles are handled *identically* after swapon time. | |
1379 | * | |
1380 | * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks | |
1381 | * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If | |
1382 | * some stray blocks are found which do not fall within the PAGE_SIZE alignment | |
1383 | * requirements, they are simply tossed out - we will never use those blocks | |
1384 | * for swapping. | |
1385 | * | |
b0d9bcd4 | 1386 | * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This |
1da177e4 LT |
1387 | * prevents root from shooting her foot off by ftruncating an in-use swapfile, |
1388 | * which will scribble on the fs. | |
1389 | * | |
1390 | * The amount of disk space which a single swap extent represents varies. | |
1391 | * Typically it is in the 1-4 megabyte range. So we can have hundreds of | |
1392 | * extents in the list. To avoid much list walking, we cache the previous | |
1393 | * search location in `curr_swap_extent', and start new searches from there. | |
1394 | * This is extremely effective. The average number of iterations in | |
1395 | * map_swap_page() has been measured at about 0.3 per page. - akpm. | |
1396 | */ | |
53092a74 | 1397 | static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
1da177e4 LT |
1398 | { |
1399 | struct inode *inode; | |
1400 | unsigned blocks_per_page; | |
1401 | unsigned long page_no; | |
1402 | unsigned blkbits; | |
1403 | sector_t probe_block; | |
1404 | sector_t last_block; | |
53092a74 HD |
1405 | sector_t lowest_block = -1; |
1406 | sector_t highest_block = 0; | |
1407 | int nr_extents = 0; | |
1da177e4 LT |
1408 | int ret; |
1409 | ||
1410 | inode = sis->swap_file->f_mapping->host; | |
1411 | if (S_ISBLK(inode->i_mode)) { | |
1412 | ret = add_swap_extent(sis, 0, sis->max, 0); | |
53092a74 | 1413 | *span = sis->pages; |
9625a5f2 | 1414 | goto out; |
1da177e4 LT |
1415 | } |
1416 | ||
1417 | blkbits = inode->i_blkbits; | |
1418 | blocks_per_page = PAGE_SIZE >> blkbits; | |
1419 | ||
1420 | /* | |
1421 | * Map all the blocks into the extent list. This code doesn't try | |
1422 | * to be very smart. | |
1423 | */ | |
1424 | probe_block = 0; | |
1425 | page_no = 0; | |
1426 | last_block = i_size_read(inode) >> blkbits; | |
1427 | while ((probe_block + blocks_per_page) <= last_block && | |
1428 | page_no < sis->max) { | |
1429 | unsigned block_in_page; | |
1430 | sector_t first_block; | |
1431 | ||
1432 | first_block = bmap(inode, probe_block); | |
1433 | if (first_block == 0) | |
1434 | goto bad_bmap; | |
1435 | ||
1436 | /* | |
1437 | * It must be PAGE_SIZE aligned on-disk | |
1438 | */ | |
1439 | if (first_block & (blocks_per_page - 1)) { | |
1440 | probe_block++; | |
1441 | goto reprobe; | |
1442 | } | |
1443 | ||
1444 | for (block_in_page = 1; block_in_page < blocks_per_page; | |
1445 | block_in_page++) { | |
1446 | sector_t block; | |
1447 | ||
1448 | block = bmap(inode, probe_block + block_in_page); | |
1449 | if (block == 0) | |
1450 | goto bad_bmap; | |
1451 | if (block != first_block + block_in_page) { | |
1452 | /* Discontiguity */ | |
1453 | probe_block++; | |
1454 | goto reprobe; | |
1455 | } | |
1456 | } | |
1457 | ||
53092a74 HD |
1458 | first_block >>= (PAGE_SHIFT - blkbits); |
1459 | if (page_no) { /* exclude the header page */ | |
1460 | if (first_block < lowest_block) | |
1461 | lowest_block = first_block; | |
1462 | if (first_block > highest_block) | |
1463 | highest_block = first_block; | |
1464 | } | |
1465 | ||
1da177e4 LT |
1466 | /* |
1467 | * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks | |
1468 | */ | |
53092a74 HD |
1469 | ret = add_swap_extent(sis, page_no, 1, first_block); |
1470 | if (ret < 0) | |
1da177e4 | 1471 | goto out; |
53092a74 | 1472 | nr_extents += ret; |
1da177e4 LT |
1473 | page_no++; |
1474 | probe_block += blocks_per_page; | |
1475 | reprobe: | |
1476 | continue; | |
1477 | } | |
53092a74 HD |
1478 | ret = nr_extents; |
1479 | *span = 1 + highest_block - lowest_block; | |
1da177e4 | 1480 | if (page_no == 0) |
e2244ec2 | 1481 | page_no = 1; /* force Empty message */ |
1da177e4 | 1482 | sis->max = page_no; |
e2244ec2 | 1483 | sis->pages = page_no - 1; |
1da177e4 | 1484 | sis->highest_bit = page_no - 1; |
9625a5f2 HD |
1485 | out: |
1486 | return ret; | |
1da177e4 LT |
1487 | bad_bmap: |
1488 | printk(KERN_ERR "swapon: swapfile has holes\n"); | |
1489 | ret = -EINVAL; | |
9625a5f2 | 1490 | goto out; |
1da177e4 LT |
1491 | } |
1492 | ||
c4ea37c2 | 1493 | SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) |
1da177e4 | 1494 | { |
73c34b6a | 1495 | struct swap_info_struct *p = NULL; |
8d69aaee | 1496 | unsigned char *swap_map; |
1da177e4 LT |
1497 | struct file *swap_file, *victim; |
1498 | struct address_space *mapping; | |
1499 | struct inode *inode; | |
73c34b6a | 1500 | char *pathname; |
1da177e4 LT |
1501 | int i, type, prev; |
1502 | int err; | |
886bb7e9 | 1503 | |
1da177e4 LT |
1504 | if (!capable(CAP_SYS_ADMIN)) |
1505 | return -EPERM; | |
1506 | ||
1507 | pathname = getname(specialfile); | |
1508 | err = PTR_ERR(pathname); | |
1509 | if (IS_ERR(pathname)) | |
1510 | goto out; | |
1511 | ||
1512 | victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0); | |
1513 | putname(pathname); | |
1514 | err = PTR_ERR(victim); | |
1515 | if (IS_ERR(victim)) | |
1516 | goto out; | |
1517 | ||
1518 | mapping = victim->f_mapping; | |
1519 | prev = -1; | |
5d337b91 | 1520 | spin_lock(&swap_lock); |
efa90a98 HD |
1521 | for (type = swap_list.head; type >= 0; type = swap_info[type]->next) { |
1522 | p = swap_info[type]; | |
22c6f8fd | 1523 | if (p->flags & SWP_WRITEOK) { |
1da177e4 LT |
1524 | if (p->swap_file->f_mapping == mapping) |
1525 | break; | |
1526 | } | |
1527 | prev = type; | |
1528 | } | |
1529 | if (type < 0) { | |
1530 | err = -EINVAL; | |
5d337b91 | 1531 | spin_unlock(&swap_lock); |
1da177e4 LT |
1532 | goto out_dput; |
1533 | } | |
1534 | if (!security_vm_enough_memory(p->pages)) | |
1535 | vm_unacct_memory(p->pages); | |
1536 | else { | |
1537 | err = -ENOMEM; | |
5d337b91 | 1538 | spin_unlock(&swap_lock); |
1da177e4 LT |
1539 | goto out_dput; |
1540 | } | |
efa90a98 | 1541 | if (prev < 0) |
1da177e4 | 1542 | swap_list.head = p->next; |
efa90a98 HD |
1543 | else |
1544 | swap_info[prev]->next = p->next; | |
1da177e4 LT |
1545 | if (type == swap_list.next) { |
1546 | /* just pick something that's safe... */ | |
1547 | swap_list.next = swap_list.head; | |
1548 | } | |
78ecba08 | 1549 | if (p->prio < 0) { |
efa90a98 HD |
1550 | for (i = p->next; i >= 0; i = swap_info[i]->next) |
1551 | swap_info[i]->prio = p->prio--; | |
78ecba08 HD |
1552 | least_priority++; |
1553 | } | |
1da177e4 LT |
1554 | nr_swap_pages -= p->pages; |
1555 | total_swap_pages -= p->pages; | |
1556 | p->flags &= ~SWP_WRITEOK; | |
5d337b91 | 1557 | spin_unlock(&swap_lock); |
fb4f88dc | 1558 | |
35451bee | 1559 | current->flags |= PF_OOM_ORIGIN; |
1da177e4 | 1560 | err = try_to_unuse(type); |
35451bee | 1561 | current->flags &= ~PF_OOM_ORIGIN; |
1da177e4 | 1562 | |
1da177e4 LT |
1563 | if (err) { |
1564 | /* re-insert swap space back into swap_list */ | |
5d337b91 | 1565 | spin_lock(&swap_lock); |
78ecba08 HD |
1566 | if (p->prio < 0) |
1567 | p->prio = --least_priority; | |
1568 | prev = -1; | |
efa90a98 HD |
1569 | for (i = swap_list.head; i >= 0; i = swap_info[i]->next) { |
1570 | if (p->prio >= swap_info[i]->prio) | |
1da177e4 | 1571 | break; |
78ecba08 HD |
1572 | prev = i; |
1573 | } | |
1da177e4 LT |
1574 | p->next = i; |
1575 | if (prev < 0) | |
efa90a98 | 1576 | swap_list.head = swap_list.next = type; |
1da177e4 | 1577 | else |
efa90a98 | 1578 | swap_info[prev]->next = type; |
1da177e4 LT |
1579 | nr_swap_pages += p->pages; |
1580 | total_swap_pages += p->pages; | |
1581 | p->flags |= SWP_WRITEOK; | |
5d337b91 | 1582 | spin_unlock(&swap_lock); |
1da177e4 LT |
1583 | goto out_dput; |
1584 | } | |
52b7efdb HD |
1585 | |
1586 | /* wait for any unplug function to finish */ | |
1587 | down_write(&swap_unplug_sem); | |
1588 | up_write(&swap_unplug_sem); | |
1589 | ||
5d337b91 | 1590 | destroy_swap_extents(p); |
570a335b HD |
1591 | if (p->flags & SWP_CONTINUED) |
1592 | free_swap_count_continuations(p); | |
1593 | ||
fc0abb14 | 1594 | mutex_lock(&swapon_mutex); |
5d337b91 HD |
1595 | spin_lock(&swap_lock); |
1596 | drain_mmlist(); | |
1597 | ||
52b7efdb | 1598 | /* wait for anyone still in scan_swap_map */ |
52b7efdb HD |
1599 | p->highest_bit = 0; /* cuts scans short */ |
1600 | while (p->flags >= SWP_SCANNING) { | |
5d337b91 | 1601 | spin_unlock(&swap_lock); |
13e4b57f | 1602 | schedule_timeout_uninterruptible(1); |
5d337b91 | 1603 | spin_lock(&swap_lock); |
52b7efdb | 1604 | } |
52b7efdb | 1605 | |
1da177e4 LT |
1606 | swap_file = p->swap_file; |
1607 | p->swap_file = NULL; | |
1608 | p->max = 0; | |
1609 | swap_map = p->swap_map; | |
1610 | p->swap_map = NULL; | |
1611 | p->flags = 0; | |
5d337b91 | 1612 | spin_unlock(&swap_lock); |
fc0abb14 | 1613 | mutex_unlock(&swapon_mutex); |
1da177e4 | 1614 | vfree(swap_map); |
27a7faa0 KH |
1615 | /* Destroy swap account informatin */ |
1616 | swap_cgroup_swapoff(type); | |
1617 | ||
1da177e4 LT |
1618 | inode = mapping->host; |
1619 | if (S_ISBLK(inode->i_mode)) { | |
1620 | struct block_device *bdev = I_BDEV(inode); | |
1621 | set_blocksize(bdev, p->old_block_size); | |
1622 | bd_release(bdev); | |
1623 | } else { | |
1b1dcc1b | 1624 | mutex_lock(&inode->i_mutex); |
1da177e4 | 1625 | inode->i_flags &= ~S_SWAPFILE; |
1b1dcc1b | 1626 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
1627 | } |
1628 | filp_close(swap_file, NULL); | |
1629 | err = 0; | |
1630 | ||
1631 | out_dput: | |
1632 | filp_close(victim, NULL); | |
1633 | out: | |
1634 | return err; | |
1635 | } | |
1636 | ||
1637 | #ifdef CONFIG_PROC_FS | |
1638 | /* iterator */ | |
1639 | static void *swap_start(struct seq_file *swap, loff_t *pos) | |
1640 | { | |
efa90a98 HD |
1641 | struct swap_info_struct *si; |
1642 | int type; | |
1da177e4 LT |
1643 | loff_t l = *pos; |
1644 | ||
fc0abb14 | 1645 | mutex_lock(&swapon_mutex); |
1da177e4 | 1646 | |
881e4aab SS |
1647 | if (!l) |
1648 | return SEQ_START_TOKEN; | |
1649 | ||
efa90a98 HD |
1650 | for (type = 0; type < nr_swapfiles; type++) { |
1651 | smp_rmb(); /* read nr_swapfiles before swap_info[type] */ | |
1652 | si = swap_info[type]; | |
1653 | if (!(si->flags & SWP_USED) || !si->swap_map) | |
1da177e4 | 1654 | continue; |
881e4aab | 1655 | if (!--l) |
efa90a98 | 1656 | return si; |
1da177e4 LT |
1657 | } |
1658 | ||
1659 | return NULL; | |
1660 | } | |
1661 | ||
1662 | static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) | |
1663 | { | |
efa90a98 HD |
1664 | struct swap_info_struct *si = v; |
1665 | int type; | |
1da177e4 | 1666 | |
881e4aab | 1667 | if (v == SEQ_START_TOKEN) |
efa90a98 HD |
1668 | type = 0; |
1669 | else | |
1670 | type = si->type + 1; | |
881e4aab | 1671 | |
efa90a98 HD |
1672 | for (; type < nr_swapfiles; type++) { |
1673 | smp_rmb(); /* read nr_swapfiles before swap_info[type] */ | |
1674 | si = swap_info[type]; | |
1675 | if (!(si->flags & SWP_USED) || !si->swap_map) | |
1da177e4 LT |
1676 | continue; |
1677 | ++*pos; | |
efa90a98 | 1678 | return si; |
1da177e4 LT |
1679 | } |
1680 | ||
1681 | return NULL; | |
1682 | } | |
1683 | ||
1684 | static void swap_stop(struct seq_file *swap, void *v) | |
1685 | { | |
fc0abb14 | 1686 | mutex_unlock(&swapon_mutex); |
1da177e4 LT |
1687 | } |
1688 | ||
1689 | static int swap_show(struct seq_file *swap, void *v) | |
1690 | { | |
efa90a98 | 1691 | struct swap_info_struct *si = v; |
1da177e4 LT |
1692 | struct file *file; |
1693 | int len; | |
1694 | ||
efa90a98 | 1695 | if (si == SEQ_START_TOKEN) { |
881e4aab SS |
1696 | seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n"); |
1697 | return 0; | |
1698 | } | |
1da177e4 | 1699 | |
efa90a98 | 1700 | file = si->swap_file; |
c32c2f63 | 1701 | len = seq_path(swap, &file->f_path, " \t\n\\"); |
6eb396dc | 1702 | seq_printf(swap, "%*s%s\t%u\t%u\t%d\n", |
886bb7e9 HD |
1703 | len < 40 ? 40 - len : 1, " ", |
1704 | S_ISBLK(file->f_path.dentry->d_inode->i_mode) ? | |
1da177e4 | 1705 | "partition" : "file\t", |
efa90a98 HD |
1706 | si->pages << (PAGE_SHIFT - 10), |
1707 | si->inuse_pages << (PAGE_SHIFT - 10), | |
1708 | si->prio); | |
1da177e4 LT |
1709 | return 0; |
1710 | } | |
1711 | ||
15ad7cdc | 1712 | static const struct seq_operations swaps_op = { |
1da177e4 LT |
1713 | .start = swap_start, |
1714 | .next = swap_next, | |
1715 | .stop = swap_stop, | |
1716 | .show = swap_show | |
1717 | }; | |
1718 | ||
1719 | static int swaps_open(struct inode *inode, struct file *file) | |
1720 | { | |
1721 | return seq_open(file, &swaps_op); | |
1722 | } | |
1723 | ||
15ad7cdc | 1724 | static const struct file_operations proc_swaps_operations = { |
1da177e4 LT |
1725 | .open = swaps_open, |
1726 | .read = seq_read, | |
1727 | .llseek = seq_lseek, | |
1728 | .release = seq_release, | |
1729 | }; | |
1730 | ||
1731 | static int __init procswaps_init(void) | |
1732 | { | |
3d71f86f | 1733 | proc_create("swaps", 0, NULL, &proc_swaps_operations); |
1da177e4 LT |
1734 | return 0; |
1735 | } | |
1736 | __initcall(procswaps_init); | |
1737 | #endif /* CONFIG_PROC_FS */ | |
1738 | ||
1796316a JB |
1739 | #ifdef MAX_SWAPFILES_CHECK |
1740 | static int __init max_swapfiles_check(void) | |
1741 | { | |
1742 | MAX_SWAPFILES_CHECK(); | |
1743 | return 0; | |
1744 | } | |
1745 | late_initcall(max_swapfiles_check); | |
1746 | #endif | |
1747 | ||
1da177e4 LT |
1748 | /* |
1749 | * Written 01/25/92 by Simmule Turner, heavily changed by Linus. | |
1750 | * | |
1751 | * The swapon system call | |
1752 | */ | |
c4ea37c2 | 1753 | SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) |
1da177e4 | 1754 | { |
73c34b6a | 1755 | struct swap_info_struct *p; |
1da177e4 LT |
1756 | char *name = NULL; |
1757 | struct block_device *bdev = NULL; | |
1758 | struct file *swap_file = NULL; | |
1759 | struct address_space *mapping; | |
1760 | unsigned int type; | |
1761 | int i, prev; | |
1762 | int error; | |
1da177e4 | 1763 | union swap_header *swap_header = NULL; |
6eb396dc HD |
1764 | unsigned int nr_good_pages = 0; |
1765 | int nr_extents = 0; | |
53092a74 | 1766 | sector_t span; |
1da177e4 | 1767 | unsigned long maxpages = 1; |
73fd8748 | 1768 | unsigned long swapfilepages; |
8d69aaee | 1769 | unsigned char *swap_map = NULL; |
1da177e4 LT |
1770 | struct page *page = NULL; |
1771 | struct inode *inode = NULL; | |
1772 | int did_down = 0; | |
1773 | ||
1774 | if (!capable(CAP_SYS_ADMIN)) | |
1775 | return -EPERM; | |
efa90a98 HD |
1776 | |
1777 | p = kzalloc(sizeof(*p), GFP_KERNEL); | |
1778 | if (!p) | |
1779 | return -ENOMEM; | |
1780 | ||
5d337b91 | 1781 | spin_lock(&swap_lock); |
efa90a98 HD |
1782 | for (type = 0; type < nr_swapfiles; type++) { |
1783 | if (!(swap_info[type]->flags & SWP_USED)) | |
1da177e4 | 1784 | break; |
efa90a98 | 1785 | } |
1da177e4 | 1786 | error = -EPERM; |
0697212a | 1787 | if (type >= MAX_SWAPFILES) { |
5d337b91 | 1788 | spin_unlock(&swap_lock); |
efa90a98 | 1789 | kfree(p); |
1da177e4 LT |
1790 | goto out; |
1791 | } | |
efa90a98 HD |
1792 | if (type >= nr_swapfiles) { |
1793 | p->type = type; | |
1794 | swap_info[type] = p; | |
1795 | /* | |
1796 | * Write swap_info[type] before nr_swapfiles, in case a | |
1797 | * racing procfs swap_start() or swap_next() is reading them. | |
1798 | * (We never shrink nr_swapfiles, we never free this entry.) | |
1799 | */ | |
1800 | smp_wmb(); | |
1801 | nr_swapfiles++; | |
1802 | } else { | |
1803 | kfree(p); | |
1804 | p = swap_info[type]; | |
1805 | /* | |
1806 | * Do not memset this entry: a racing procfs swap_next() | |
1807 | * would be relying on p->type to remain valid. | |
1808 | */ | |
1809 | } | |
9625a5f2 | 1810 | INIT_LIST_HEAD(&p->first_swap_extent.list); |
1da177e4 | 1811 | p->flags = SWP_USED; |
1da177e4 | 1812 | p->next = -1; |
5d337b91 | 1813 | spin_unlock(&swap_lock); |
efa90a98 | 1814 | |
1da177e4 LT |
1815 | name = getname(specialfile); |
1816 | error = PTR_ERR(name); | |
1817 | if (IS_ERR(name)) { | |
1818 | name = NULL; | |
1819 | goto bad_swap_2; | |
1820 | } | |
1821 | swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0); | |
1822 | error = PTR_ERR(swap_file); | |
1823 | if (IS_ERR(swap_file)) { | |
1824 | swap_file = NULL; | |
1825 | goto bad_swap_2; | |
1826 | } | |
1827 | ||
1828 | p->swap_file = swap_file; | |
1829 | mapping = swap_file->f_mapping; | |
1830 | inode = mapping->host; | |
1831 | ||
1832 | error = -EBUSY; | |
1833 | for (i = 0; i < nr_swapfiles; i++) { | |
efa90a98 | 1834 | struct swap_info_struct *q = swap_info[i]; |
1da177e4 LT |
1835 | |
1836 | if (i == type || !q->swap_file) | |
1837 | continue; | |
1838 | if (mapping == q->swap_file->f_mapping) | |
1839 | goto bad_swap; | |
1840 | } | |
1841 | ||
1842 | error = -EINVAL; | |
1843 | if (S_ISBLK(inode->i_mode)) { | |
1844 | bdev = I_BDEV(inode); | |
1845 | error = bd_claim(bdev, sys_swapon); | |
1846 | if (error < 0) { | |
1847 | bdev = NULL; | |
f7b3a435 | 1848 | error = -EINVAL; |
1da177e4 LT |
1849 | goto bad_swap; |
1850 | } | |
1851 | p->old_block_size = block_size(bdev); | |
1852 | error = set_blocksize(bdev, PAGE_SIZE); | |
1853 | if (error < 0) | |
1854 | goto bad_swap; | |
1855 | p->bdev = bdev; | |
1856 | } else if (S_ISREG(inode->i_mode)) { | |
1857 | p->bdev = inode->i_sb->s_bdev; | |
1b1dcc1b | 1858 | mutex_lock(&inode->i_mutex); |
1da177e4 LT |
1859 | did_down = 1; |
1860 | if (IS_SWAPFILE(inode)) { | |
1861 | error = -EBUSY; | |
1862 | goto bad_swap; | |
1863 | } | |
1864 | } else { | |
1865 | goto bad_swap; | |
1866 | } | |
1867 | ||
73fd8748 | 1868 | swapfilepages = i_size_read(inode) >> PAGE_SHIFT; |
1da177e4 LT |
1869 | |
1870 | /* | |
1871 | * Read the swap header. | |
1872 | */ | |
1873 | if (!mapping->a_ops->readpage) { | |
1874 | error = -EINVAL; | |
1875 | goto bad_swap; | |
1876 | } | |
090d2b18 | 1877 | page = read_mapping_page(mapping, 0, swap_file); |
1da177e4 LT |
1878 | if (IS_ERR(page)) { |
1879 | error = PTR_ERR(page); | |
1880 | goto bad_swap; | |
1881 | } | |
81e33971 | 1882 | swap_header = kmap(page); |
1da177e4 | 1883 | |
81e33971 | 1884 | if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) { |
e97a3111 | 1885 | printk(KERN_ERR "Unable to find swap-space signature\n"); |
1da177e4 LT |
1886 | error = -EINVAL; |
1887 | goto bad_swap; | |
1888 | } | |
886bb7e9 | 1889 | |
81e33971 HD |
1890 | /* swap partition endianess hack... */ |
1891 | if (swab32(swap_header->info.version) == 1) { | |
1892 | swab32s(&swap_header->info.version); | |
1893 | swab32s(&swap_header->info.last_page); | |
1894 | swab32s(&swap_header->info.nr_badpages); | |
1895 | for (i = 0; i < swap_header->info.nr_badpages; i++) | |
1896 | swab32s(&swap_header->info.badpages[i]); | |
1897 | } | |
1898 | /* Check the swap header's sub-version */ | |
1899 | if (swap_header->info.version != 1) { | |
1900 | printk(KERN_WARNING | |
1901 | "Unable to handle swap header version %d\n", | |
1902 | swap_header->info.version); | |
1da177e4 LT |
1903 | error = -EINVAL; |
1904 | goto bad_swap; | |
81e33971 | 1905 | } |
1da177e4 | 1906 | |
81e33971 HD |
1907 | p->lowest_bit = 1; |
1908 | p->cluster_next = 1; | |
efa90a98 | 1909 | p->cluster_nr = 0; |
52b7efdb | 1910 | |
81e33971 HD |
1911 | /* |
1912 | * Find out how many pages are allowed for a single swap | |
1913 | * device. There are two limiting factors: 1) the number of | |
1914 | * bits for the swap offset in the swp_entry_t type and | |
1915 | * 2) the number of bits in the a swap pte as defined by | |
1916 | * the different architectures. In order to find the | |
1917 | * largest possible bit mask a swap entry with swap type 0 | |
1918 | * and swap offset ~0UL is created, encoded to a swap pte, | |
1919 | * decoded to a swp_entry_t again and finally the swap | |
1920 | * offset is extracted. This will mask all the bits from | |
1921 | * the initial ~0UL mask that can't be encoded in either | |
1922 | * the swp_entry_t or the architecture definition of a | |
1923 | * swap pte. | |
1924 | */ | |
1925 | maxpages = swp_offset(pte_to_swp_entry( | |
1926 | swp_entry_to_pte(swp_entry(0, ~0UL)))) - 1; | |
1927 | if (maxpages > swap_header->info.last_page) | |
1928 | maxpages = swap_header->info.last_page; | |
1929 | p->highest_bit = maxpages - 1; | |
1da177e4 | 1930 | |
81e33971 HD |
1931 | error = -EINVAL; |
1932 | if (!maxpages) | |
1933 | goto bad_swap; | |
1934 | if (swapfilepages && maxpages > swapfilepages) { | |
1935 | printk(KERN_WARNING | |
1936 | "Swap area shorter than signature indicates\n"); | |
1937 | goto bad_swap; | |
1938 | } | |
1939 | if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) | |
1940 | goto bad_swap; | |
1941 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) | |
1942 | goto bad_swap; | |
cd105df4 | 1943 | |
81e33971 | 1944 | /* OK, set up the swap map and apply the bad block list */ |
8d69aaee | 1945 | swap_map = vmalloc(maxpages); |
81e33971 HD |
1946 | if (!swap_map) { |
1947 | error = -ENOMEM; | |
1948 | goto bad_swap; | |
1949 | } | |
1da177e4 | 1950 | |
8d69aaee | 1951 | memset(swap_map, 0, maxpages); |
81e33971 HD |
1952 | for (i = 0; i < swap_header->info.nr_badpages; i++) { |
1953 | int page_nr = swap_header->info.badpages[i]; | |
1954 | if (page_nr <= 0 || page_nr >= swap_header->info.last_page) { | |
1955 | error = -EINVAL; | |
1da177e4 | 1956 | goto bad_swap; |
81e33971 HD |
1957 | } |
1958 | swap_map[page_nr] = SWAP_MAP_BAD; | |
1da177e4 | 1959 | } |
27a7faa0 KH |
1960 | |
1961 | error = swap_cgroup_swapon(type, maxpages); | |
1962 | if (error) | |
1963 | goto bad_swap; | |
1964 | ||
81e33971 HD |
1965 | nr_good_pages = swap_header->info.last_page - |
1966 | swap_header->info.nr_badpages - | |
1967 | 1 /* header page */; | |
e2244ec2 | 1968 | |
e2244ec2 | 1969 | if (nr_good_pages) { |
78ecba08 | 1970 | swap_map[0] = SWAP_MAP_BAD; |
e2244ec2 HD |
1971 | p->max = maxpages; |
1972 | p->pages = nr_good_pages; | |
53092a74 HD |
1973 | nr_extents = setup_swap_extents(p, &span); |
1974 | if (nr_extents < 0) { | |
1975 | error = nr_extents; | |
e2244ec2 | 1976 | goto bad_swap; |
53092a74 | 1977 | } |
e2244ec2 HD |
1978 | nr_good_pages = p->pages; |
1979 | } | |
1da177e4 LT |
1980 | if (!nr_good_pages) { |
1981 | printk(KERN_WARNING "Empty swap-file\n"); | |
1982 | error = -EINVAL; | |
1983 | goto bad_swap; | |
1984 | } | |
1da177e4 | 1985 | |
3bd0f0c7 SJ |
1986 | if (p->bdev) { |
1987 | if (blk_queue_nonrot(bdev_get_queue(p->bdev))) { | |
1988 | p->flags |= SWP_SOLIDSTATE; | |
1989 | p->cluster_next = 1 + (random32() % p->highest_bit); | |
1990 | } | |
1991 | if (discard_swap(p) == 0) | |
1992 | p->flags |= SWP_DISCARDABLE; | |
20137a49 | 1993 | } |
6a6ba831 | 1994 | |
fc0abb14 | 1995 | mutex_lock(&swapon_mutex); |
5d337b91 | 1996 | spin_lock(&swap_lock); |
78ecba08 HD |
1997 | if (swap_flags & SWAP_FLAG_PREFER) |
1998 | p->prio = | |
1999 | (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; | |
2000 | else | |
2001 | p->prio = --least_priority; | |
2002 | p->swap_map = swap_map; | |
22c6f8fd | 2003 | p->flags |= SWP_WRITEOK; |
1da177e4 LT |
2004 | nr_swap_pages += nr_good_pages; |
2005 | total_swap_pages += nr_good_pages; | |
53092a74 | 2006 | |
6eb396dc | 2007 | printk(KERN_INFO "Adding %uk swap on %s. " |
20137a49 | 2008 | "Priority:%d extents:%d across:%lluk %s%s\n", |
53092a74 | 2009 | nr_good_pages<<(PAGE_SHIFT-10), name, p->prio, |
6a6ba831 | 2010 | nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), |
20137a49 HD |
2011 | (p->flags & SWP_SOLIDSTATE) ? "SS" : "", |
2012 | (p->flags & SWP_DISCARDABLE) ? "D" : ""); | |
1da177e4 LT |
2013 | |
2014 | /* insert swap space into swap_list: */ | |
2015 | prev = -1; | |
efa90a98 HD |
2016 | for (i = swap_list.head; i >= 0; i = swap_info[i]->next) { |
2017 | if (p->prio >= swap_info[i]->prio) | |
1da177e4 | 2018 | break; |
1da177e4 LT |
2019 | prev = i; |
2020 | } | |
2021 | p->next = i; | |
efa90a98 HD |
2022 | if (prev < 0) |
2023 | swap_list.head = swap_list.next = type; | |
2024 | else | |
2025 | swap_info[prev]->next = type; | |
5d337b91 | 2026 | spin_unlock(&swap_lock); |
fc0abb14 | 2027 | mutex_unlock(&swapon_mutex); |
1da177e4 LT |
2028 | error = 0; |
2029 | goto out; | |
2030 | bad_swap: | |
2031 | if (bdev) { | |
2032 | set_blocksize(bdev, p->old_block_size); | |
2033 | bd_release(bdev); | |
2034 | } | |
4cd3bb10 | 2035 | destroy_swap_extents(p); |
27a7faa0 | 2036 | swap_cgroup_swapoff(type); |
1da177e4 | 2037 | bad_swap_2: |
5d337b91 | 2038 | spin_lock(&swap_lock); |
1da177e4 | 2039 | p->swap_file = NULL; |
1da177e4 | 2040 | p->flags = 0; |
5d337b91 | 2041 | spin_unlock(&swap_lock); |
1da177e4 LT |
2042 | vfree(swap_map); |
2043 | if (swap_file) | |
2044 | filp_close(swap_file, NULL); | |
2045 | out: | |
2046 | if (page && !IS_ERR(page)) { | |
2047 | kunmap(page); | |
2048 | page_cache_release(page); | |
2049 | } | |
2050 | if (name) | |
2051 | putname(name); | |
2052 | if (did_down) { | |
2053 | if (!error) | |
2054 | inode->i_flags |= S_SWAPFILE; | |
1b1dcc1b | 2055 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
2056 | } |
2057 | return error; | |
2058 | } | |
2059 | ||
2060 | void si_swapinfo(struct sysinfo *val) | |
2061 | { | |
efa90a98 | 2062 | unsigned int type; |
1da177e4 LT |
2063 | unsigned long nr_to_be_unused = 0; |
2064 | ||
5d337b91 | 2065 | spin_lock(&swap_lock); |
efa90a98 HD |
2066 | for (type = 0; type < nr_swapfiles; type++) { |
2067 | struct swap_info_struct *si = swap_info[type]; | |
2068 | ||
2069 | if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK)) | |
2070 | nr_to_be_unused += si->inuse_pages; | |
1da177e4 LT |
2071 | } |
2072 | val->freeswap = nr_swap_pages + nr_to_be_unused; | |
2073 | val->totalswap = total_swap_pages + nr_to_be_unused; | |
5d337b91 | 2074 | spin_unlock(&swap_lock); |
1da177e4 LT |
2075 | } |
2076 | ||
2077 | /* | |
2078 | * Verify that a swap entry is valid and increment its swap map count. | |
2079 | * | |
355cfa73 KH |
2080 | * Returns error code in following case. |
2081 | * - success -> 0 | |
2082 | * - swp_entry is invalid -> EINVAL | |
2083 | * - swp_entry is migration entry -> EINVAL | |
2084 | * - swap-cache reference is requested but there is already one. -> EEXIST | |
2085 | * - swap-cache reference is requested but the entry is not used. -> ENOENT | |
570a335b | 2086 | * - swap-mapped reference requested but needs continued swap count. -> ENOMEM |
1da177e4 | 2087 | */ |
8d69aaee | 2088 | static int __swap_duplicate(swp_entry_t entry, unsigned char usage) |
1da177e4 | 2089 | { |
73c34b6a | 2090 | struct swap_info_struct *p; |
1da177e4 | 2091 | unsigned long offset, type; |
8d69aaee HD |
2092 | unsigned char count; |
2093 | unsigned char has_cache; | |
253d553b | 2094 | int err = -EINVAL; |
1da177e4 | 2095 | |
a7420aa5 | 2096 | if (non_swap_entry(entry)) |
253d553b | 2097 | goto out; |
0697212a | 2098 | |
1da177e4 LT |
2099 | type = swp_type(entry); |
2100 | if (type >= nr_swapfiles) | |
2101 | goto bad_file; | |
efa90a98 | 2102 | p = swap_info[type]; |
1da177e4 LT |
2103 | offset = swp_offset(entry); |
2104 | ||
5d337b91 | 2105 | spin_lock(&swap_lock); |
355cfa73 KH |
2106 | if (unlikely(offset >= p->max)) |
2107 | goto unlock_out; | |
2108 | ||
253d553b HD |
2109 | count = p->swap_map[offset]; |
2110 | has_cache = count & SWAP_HAS_CACHE; | |
2111 | count &= ~SWAP_HAS_CACHE; | |
2112 | err = 0; | |
355cfa73 | 2113 | |
253d553b | 2114 | if (usage == SWAP_HAS_CACHE) { |
355cfa73 KH |
2115 | |
2116 | /* set SWAP_HAS_CACHE if there is no cache and entry is used */ | |
253d553b HD |
2117 | if (!has_cache && count) |
2118 | has_cache = SWAP_HAS_CACHE; | |
2119 | else if (has_cache) /* someone else added cache */ | |
2120 | err = -EEXIST; | |
2121 | else /* no users remaining */ | |
2122 | err = -ENOENT; | |
355cfa73 KH |
2123 | |
2124 | } else if (count || has_cache) { | |
253d553b | 2125 | |
570a335b HD |
2126 | if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX) |
2127 | count += usage; | |
2128 | else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) | |
253d553b | 2129 | err = -EINVAL; |
570a335b HD |
2130 | else if (swap_count_continued(p, offset, count)) |
2131 | count = COUNT_CONTINUED; | |
2132 | else | |
2133 | err = -ENOMEM; | |
355cfa73 | 2134 | } else |
253d553b HD |
2135 | err = -ENOENT; /* unused swap entry */ |
2136 | ||
2137 | p->swap_map[offset] = count | has_cache; | |
2138 | ||
355cfa73 | 2139 | unlock_out: |
5d337b91 | 2140 | spin_unlock(&swap_lock); |
1da177e4 | 2141 | out: |
253d553b | 2142 | return err; |
1da177e4 LT |
2143 | |
2144 | bad_file: | |
2145 | printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val); | |
2146 | goto out; | |
2147 | } | |
253d553b | 2148 | |
aaa46865 HD |
2149 | /* |
2150 | * Help swapoff by noting that swap entry belongs to shmem/tmpfs | |
2151 | * (in which case its reference count is never incremented). | |
2152 | */ | |
2153 | void swap_shmem_alloc(swp_entry_t entry) | |
2154 | { | |
2155 | __swap_duplicate(entry, SWAP_MAP_SHMEM); | |
2156 | } | |
2157 | ||
355cfa73 KH |
2158 | /* |
2159 | * increase reference count of swap entry by 1. | |
2160 | */ | |
570a335b | 2161 | int swap_duplicate(swp_entry_t entry) |
355cfa73 | 2162 | { |
570a335b HD |
2163 | int err = 0; |
2164 | ||
2165 | while (!err && __swap_duplicate(entry, 1) == -ENOMEM) | |
2166 | err = add_swap_count_continuation(entry, GFP_ATOMIC); | |
2167 | return err; | |
355cfa73 | 2168 | } |
1da177e4 | 2169 | |
cb4b86ba | 2170 | /* |
355cfa73 KH |
2171 | * @entry: swap entry for which we allocate swap cache. |
2172 | * | |
73c34b6a | 2173 | * Called when allocating swap cache for existing swap entry, |
355cfa73 KH |
2174 | * This can return error codes. Returns 0 at success. |
2175 | * -EBUSY means there is a swap cache. | |
2176 | * Note: return code is different from swap_duplicate(). | |
cb4b86ba KH |
2177 | */ |
2178 | int swapcache_prepare(swp_entry_t entry) | |
2179 | { | |
253d553b | 2180 | return __swap_duplicate(entry, SWAP_HAS_CACHE); |
cb4b86ba KH |
2181 | } |
2182 | ||
1da177e4 | 2183 | /* |
5d337b91 | 2184 | * swap_lock prevents swap_map being freed. Don't grab an extra |
1da177e4 LT |
2185 | * reference on the swaphandle, it doesn't matter if it becomes unused. |
2186 | */ | |
2187 | int valid_swaphandles(swp_entry_t entry, unsigned long *offset) | |
2188 | { | |
8952898b | 2189 | struct swap_info_struct *si; |
3f9e7949 | 2190 | int our_page_cluster = page_cluster; |
8952898b HD |
2191 | pgoff_t target, toff; |
2192 | pgoff_t base, end; | |
2193 | int nr_pages = 0; | |
1da177e4 | 2194 | |
3f9e7949 | 2195 | if (!our_page_cluster) /* no readahead */ |
1da177e4 | 2196 | return 0; |
8952898b | 2197 | |
efa90a98 | 2198 | si = swap_info[swp_type(entry)]; |
8952898b HD |
2199 | target = swp_offset(entry); |
2200 | base = (target >> our_page_cluster) << our_page_cluster; | |
2201 | end = base + (1 << our_page_cluster); | |
2202 | if (!base) /* first page is swap header */ | |
2203 | base++; | |
1da177e4 | 2204 | |
5d337b91 | 2205 | spin_lock(&swap_lock); |
8952898b HD |
2206 | if (end > si->max) /* don't go beyond end of map */ |
2207 | end = si->max; | |
2208 | ||
2209 | /* Count contiguous allocated slots above our target */ | |
2210 | for (toff = target; ++toff < end; nr_pages++) { | |
2211 | /* Don't read in free or bad pages */ | |
2212 | if (!si->swap_map[toff]) | |
2213 | break; | |
355cfa73 | 2214 | if (swap_count(si->swap_map[toff]) == SWAP_MAP_BAD) |
1da177e4 | 2215 | break; |
8952898b HD |
2216 | } |
2217 | /* Count contiguous allocated slots below our target */ | |
2218 | for (toff = target; --toff >= base; nr_pages++) { | |
1da177e4 | 2219 | /* Don't read in free or bad pages */ |
8952898b | 2220 | if (!si->swap_map[toff]) |
1da177e4 | 2221 | break; |
355cfa73 | 2222 | if (swap_count(si->swap_map[toff]) == SWAP_MAP_BAD) |
1da177e4 | 2223 | break; |
8952898b | 2224 | } |
5d337b91 | 2225 | spin_unlock(&swap_lock); |
8952898b HD |
2226 | |
2227 | /* | |
2228 | * Indicate starting offset, and return number of pages to get: | |
2229 | * if only 1, say 0, since there's then no readahead to be done. | |
2230 | */ | |
2231 | *offset = ++toff; | |
2232 | return nr_pages? ++nr_pages: 0; | |
1da177e4 | 2233 | } |
570a335b HD |
2234 | |
2235 | /* | |
2236 | * add_swap_count_continuation - called when a swap count is duplicated | |
2237 | * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's | |
2238 | * page of the original vmalloc'ed swap_map, to hold the continuation count | |
2239 | * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called | |
2240 | * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc. | |
2241 | * | |
2242 | * These continuation pages are seldom referenced: the common paths all work | |
2243 | * on the original swap_map, only referring to a continuation page when the | |
2244 | * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX. | |
2245 | * | |
2246 | * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding | |
2247 | * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL) | |
2248 | * can be called after dropping locks. | |
2249 | */ | |
2250 | int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask) | |
2251 | { | |
2252 | struct swap_info_struct *si; | |
2253 | struct page *head; | |
2254 | struct page *page; | |
2255 | struct page *list_page; | |
2256 | pgoff_t offset; | |
2257 | unsigned char count; | |
2258 | ||
2259 | /* | |
2260 | * When debugging, it's easier to use __GFP_ZERO here; but it's better | |
2261 | * for latency not to zero a page while GFP_ATOMIC and holding locks. | |
2262 | */ | |
2263 | page = alloc_page(gfp_mask | __GFP_HIGHMEM); | |
2264 | ||
2265 | si = swap_info_get(entry); | |
2266 | if (!si) { | |
2267 | /* | |
2268 | * An acceptable race has occurred since the failing | |
2269 | * __swap_duplicate(): the swap entry has been freed, | |
2270 | * perhaps even the whole swap_map cleared for swapoff. | |
2271 | */ | |
2272 | goto outer; | |
2273 | } | |
2274 | ||
2275 | offset = swp_offset(entry); | |
2276 | count = si->swap_map[offset] & ~SWAP_HAS_CACHE; | |
2277 | ||
2278 | if ((count & ~COUNT_CONTINUED) != SWAP_MAP_MAX) { | |
2279 | /* | |
2280 | * The higher the swap count, the more likely it is that tasks | |
2281 | * will race to add swap count continuation: we need to avoid | |
2282 | * over-provisioning. | |
2283 | */ | |
2284 | goto out; | |
2285 | } | |
2286 | ||
2287 | if (!page) { | |
2288 | spin_unlock(&swap_lock); | |
2289 | return -ENOMEM; | |
2290 | } | |
2291 | ||
2292 | /* | |
2293 | * We are fortunate that although vmalloc_to_page uses pte_offset_map, | |
2294 | * no architecture is using highmem pages for kernel pagetables: so it | |
2295 | * will not corrupt the GFP_ATOMIC caller's atomic pagetable kmaps. | |
2296 | */ | |
2297 | head = vmalloc_to_page(si->swap_map + offset); | |
2298 | offset &= ~PAGE_MASK; | |
2299 | ||
2300 | /* | |
2301 | * Page allocation does not initialize the page's lru field, | |
2302 | * but it does always reset its private field. | |
2303 | */ | |
2304 | if (!page_private(head)) { | |
2305 | BUG_ON(count & COUNT_CONTINUED); | |
2306 | INIT_LIST_HEAD(&head->lru); | |
2307 | set_page_private(head, SWP_CONTINUED); | |
2308 | si->flags |= SWP_CONTINUED; | |
2309 | } | |
2310 | ||
2311 | list_for_each_entry(list_page, &head->lru, lru) { | |
2312 | unsigned char *map; | |
2313 | ||
2314 | /* | |
2315 | * If the previous map said no continuation, but we've found | |
2316 | * a continuation page, free our allocation and use this one. | |
2317 | */ | |
2318 | if (!(count & COUNT_CONTINUED)) | |
2319 | goto out; | |
2320 | ||
2321 | map = kmap_atomic(list_page, KM_USER0) + offset; | |
2322 | count = *map; | |
2323 | kunmap_atomic(map, KM_USER0); | |
2324 | ||
2325 | /* | |
2326 | * If this continuation count now has some space in it, | |
2327 | * free our allocation and use this one. | |
2328 | */ | |
2329 | if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX) | |
2330 | goto out; | |
2331 | } | |
2332 | ||
2333 | list_add_tail(&page->lru, &head->lru); | |
2334 | page = NULL; /* now it's attached, don't free it */ | |
2335 | out: | |
2336 | spin_unlock(&swap_lock); | |
2337 | outer: | |
2338 | if (page) | |
2339 | __free_page(page); | |
2340 | return 0; | |
2341 | } | |
2342 | ||
2343 | /* | |
2344 | * swap_count_continued - when the original swap_map count is incremented | |
2345 | * from SWAP_MAP_MAX, check if there is already a continuation page to carry | |
2346 | * into, carry if so, or else fail until a new continuation page is allocated; | |
2347 | * when the original swap_map count is decremented from 0 with continuation, | |
2348 | * borrow from the continuation and report whether it still holds more. | |
2349 | * Called while __swap_duplicate() or swap_entry_free() holds swap_lock. | |
2350 | */ | |
2351 | static bool swap_count_continued(struct swap_info_struct *si, | |
2352 | pgoff_t offset, unsigned char count) | |
2353 | { | |
2354 | struct page *head; | |
2355 | struct page *page; | |
2356 | unsigned char *map; | |
2357 | ||
2358 | head = vmalloc_to_page(si->swap_map + offset); | |
2359 | if (page_private(head) != SWP_CONTINUED) { | |
2360 | BUG_ON(count & COUNT_CONTINUED); | |
2361 | return false; /* need to add count continuation */ | |
2362 | } | |
2363 | ||
2364 | offset &= ~PAGE_MASK; | |
2365 | page = list_entry(head->lru.next, struct page, lru); | |
2366 | map = kmap_atomic(page, KM_USER0) + offset; | |
2367 | ||
2368 | if (count == SWAP_MAP_MAX) /* initial increment from swap_map */ | |
2369 | goto init_map; /* jump over SWAP_CONT_MAX checks */ | |
2370 | ||
2371 | if (count == (SWAP_MAP_MAX | COUNT_CONTINUED)) { /* incrementing */ | |
2372 | /* | |
2373 | * Think of how you add 1 to 999 | |
2374 | */ | |
2375 | while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) { | |
2376 | kunmap_atomic(map, KM_USER0); | |
2377 | page = list_entry(page->lru.next, struct page, lru); | |
2378 | BUG_ON(page == head); | |
2379 | map = kmap_atomic(page, KM_USER0) + offset; | |
2380 | } | |
2381 | if (*map == SWAP_CONT_MAX) { | |
2382 | kunmap_atomic(map, KM_USER0); | |
2383 | page = list_entry(page->lru.next, struct page, lru); | |
2384 | if (page == head) | |
2385 | return false; /* add count continuation */ | |
2386 | map = kmap_atomic(page, KM_USER0) + offset; | |
2387 | init_map: *map = 0; /* we didn't zero the page */ | |
2388 | } | |
2389 | *map += 1; | |
2390 | kunmap_atomic(map, KM_USER0); | |
2391 | page = list_entry(page->lru.prev, struct page, lru); | |
2392 | while (page != head) { | |
2393 | map = kmap_atomic(page, KM_USER0) + offset; | |
2394 | *map = COUNT_CONTINUED; | |
2395 | kunmap_atomic(map, KM_USER0); | |
2396 | page = list_entry(page->lru.prev, struct page, lru); | |
2397 | } | |
2398 | return true; /* incremented */ | |
2399 | ||
2400 | } else { /* decrementing */ | |
2401 | /* | |
2402 | * Think of how you subtract 1 from 1000 | |
2403 | */ | |
2404 | BUG_ON(count != COUNT_CONTINUED); | |
2405 | while (*map == COUNT_CONTINUED) { | |
2406 | kunmap_atomic(map, KM_USER0); | |
2407 | page = list_entry(page->lru.next, struct page, lru); | |
2408 | BUG_ON(page == head); | |
2409 | map = kmap_atomic(page, KM_USER0) + offset; | |
2410 | } | |
2411 | BUG_ON(*map == 0); | |
2412 | *map -= 1; | |
2413 | if (*map == 0) | |
2414 | count = 0; | |
2415 | kunmap_atomic(map, KM_USER0); | |
2416 | page = list_entry(page->lru.prev, struct page, lru); | |
2417 | while (page != head) { | |
2418 | map = kmap_atomic(page, KM_USER0) + offset; | |
2419 | *map = SWAP_CONT_MAX | count; | |
2420 | count = COUNT_CONTINUED; | |
2421 | kunmap_atomic(map, KM_USER0); | |
2422 | page = list_entry(page->lru.prev, struct page, lru); | |
2423 | } | |
2424 | return count == COUNT_CONTINUED; | |
2425 | } | |
2426 | } | |
2427 | ||
2428 | /* | |
2429 | * free_swap_count_continuations - swapoff free all the continuation pages | |
2430 | * appended to the swap_map, after swap_map is quiesced, before vfree'ing it. | |
2431 | */ | |
2432 | static void free_swap_count_continuations(struct swap_info_struct *si) | |
2433 | { | |
2434 | pgoff_t offset; | |
2435 | ||
2436 | for (offset = 0; offset < si->max; offset += PAGE_SIZE) { | |
2437 | struct page *head; | |
2438 | head = vmalloc_to_page(si->swap_map + offset); | |
2439 | if (page_private(head)) { | |
2440 | struct list_head *this, *next; | |
2441 | list_for_each_safe(this, next, &head->lru) { | |
2442 | struct page *page; | |
2443 | page = list_entry(this, struct page, lru); | |
2444 | list_del(this); | |
2445 | __free_page(page); | |
2446 | } | |
2447 | } | |
2448 | } | |
2449 | } |