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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> | |
25 | #include <linux/rmap.h> | |
26 | #include <linux/security.h> | |
27 | #include <linux/backing-dev.h> | |
fc0abb14 | 28 | #include <linux/mutex.h> |
c59ede7b | 29 | #include <linux/capability.h> |
1da177e4 | 30 | #include <linux/syscalls.h> |
8a9f3ccd | 31 | #include <linux/memcontrol.h> |
1da177e4 LT |
32 | |
33 | #include <asm/pgtable.h> | |
34 | #include <asm/tlbflush.h> | |
35 | #include <linux/swapops.h> | |
36 | ||
7c363b8c AB |
37 | static DEFINE_SPINLOCK(swap_lock); |
38 | static unsigned int nr_swapfiles; | |
b962716b | 39 | long nr_swap_pages; |
1da177e4 LT |
40 | long total_swap_pages; |
41 | static int swap_overflow; | |
78ecba08 | 42 | static int least_priority; |
1da177e4 | 43 | |
1da177e4 LT |
44 | static const char Bad_file[] = "Bad swap file entry "; |
45 | static const char Unused_file[] = "Unused swap file entry "; | |
46 | static const char Bad_offset[] = "Bad swap offset entry "; | |
47 | static const char Unused_offset[] = "Unused swap offset entry "; | |
48 | ||
7c363b8c | 49 | static struct swap_list_t swap_list = {-1, -1}; |
1da177e4 | 50 | |
f577eb30 | 51 | static struct swap_info_struct swap_info[MAX_SWAPFILES]; |
1da177e4 | 52 | |
fc0abb14 | 53 | static DEFINE_MUTEX(swapon_mutex); |
1da177e4 LT |
54 | |
55 | /* | |
56 | * We need this because the bdev->unplug_fn can sleep and we cannot | |
5d337b91 | 57 | * hold swap_lock while calling the unplug_fn. And swap_lock |
fc0abb14 | 58 | * cannot be turned into a mutex. |
1da177e4 LT |
59 | */ |
60 | static DECLARE_RWSEM(swap_unplug_sem); | |
61 | ||
1da177e4 LT |
62 | void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page) |
63 | { | |
64 | swp_entry_t entry; | |
65 | ||
66 | down_read(&swap_unplug_sem); | |
4c21e2f2 | 67 | entry.val = page_private(page); |
1da177e4 LT |
68 | if (PageSwapCache(page)) { |
69 | struct block_device *bdev = swap_info[swp_type(entry)].bdev; | |
70 | struct backing_dev_info *bdi; | |
71 | ||
72 | /* | |
73 | * If the page is removed from swapcache from under us (with a | |
74 | * racy try_to_unuse/swapoff) we need an additional reference | |
4c21e2f2 HD |
75 | * count to avoid reading garbage from page_private(page) above. |
76 | * If the WARN_ON triggers during a swapoff it maybe the race | |
1da177e4 LT |
77 | * condition and it's harmless. However if it triggers without |
78 | * swapoff it signals a problem. | |
79 | */ | |
80 | WARN_ON(page_count(page) <= 1); | |
81 | ||
82 | bdi = bdev->bd_inode->i_mapping->backing_dev_info; | |
ba32311e | 83 | blk_run_backing_dev(bdi, page); |
1da177e4 LT |
84 | } |
85 | up_read(&swap_unplug_sem); | |
86 | } | |
87 | ||
6a6ba831 HD |
88 | /* |
89 | * swapon tell device that all the old swap contents can be discarded, | |
90 | * to allow the swap device to optimize its wear-levelling. | |
91 | */ | |
92 | static int discard_swap(struct swap_info_struct *si) | |
93 | { | |
94 | struct swap_extent *se; | |
95 | int err = 0; | |
96 | ||
97 | list_for_each_entry(se, &si->extent_list, list) { | |
98 | sector_t start_block = se->start_block << (PAGE_SHIFT - 9); | |
858a2990 | 99 | sector_t nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); |
6a6ba831 HD |
100 | |
101 | if (se->start_page == 0) { | |
102 | /* Do not discard the swap header page! */ | |
103 | start_block += 1 << (PAGE_SHIFT - 9); | |
104 | nr_blocks -= 1 << (PAGE_SHIFT - 9); | |
105 | if (!nr_blocks) | |
106 | continue; | |
107 | } | |
108 | ||
109 | err = blkdev_issue_discard(si->bdev, start_block, | |
110 | nr_blocks, GFP_KERNEL); | |
111 | if (err) | |
112 | break; | |
113 | ||
114 | cond_resched(); | |
115 | } | |
116 | return err; /* That will often be -EOPNOTSUPP */ | |
117 | } | |
118 | ||
7992fde7 HD |
119 | /* |
120 | * swap allocation tell device that a cluster of swap can now be discarded, | |
121 | * to allow the swap device to optimize its wear-levelling. | |
122 | */ | |
123 | static void discard_swap_cluster(struct swap_info_struct *si, | |
124 | pgoff_t start_page, pgoff_t nr_pages) | |
125 | { | |
126 | struct swap_extent *se = si->curr_swap_extent; | |
127 | int found_extent = 0; | |
128 | ||
129 | while (nr_pages) { | |
130 | struct list_head *lh; | |
131 | ||
132 | if (se->start_page <= start_page && | |
133 | start_page < se->start_page + se->nr_pages) { | |
134 | pgoff_t offset = start_page - se->start_page; | |
135 | sector_t start_block = se->start_block + offset; | |
858a2990 | 136 | sector_t nr_blocks = se->nr_pages - offset; |
7992fde7 HD |
137 | |
138 | if (nr_blocks > nr_pages) | |
139 | nr_blocks = nr_pages; | |
140 | start_page += nr_blocks; | |
141 | nr_pages -= nr_blocks; | |
142 | ||
143 | if (!found_extent++) | |
144 | si->curr_swap_extent = se; | |
145 | ||
146 | start_block <<= PAGE_SHIFT - 9; | |
147 | nr_blocks <<= PAGE_SHIFT - 9; | |
148 | if (blkdev_issue_discard(si->bdev, start_block, | |
149 | nr_blocks, GFP_NOIO)) | |
150 | break; | |
151 | } | |
152 | ||
153 | lh = se->list.next; | |
154 | if (lh == &si->extent_list) | |
155 | lh = lh->next; | |
156 | se = list_entry(lh, struct swap_extent, list); | |
157 | } | |
158 | } | |
159 | ||
160 | static int wait_for_discard(void *word) | |
161 | { | |
162 | schedule(); | |
163 | return 0; | |
164 | } | |
165 | ||
048c27fd HD |
166 | #define SWAPFILE_CLUSTER 256 |
167 | #define LATENCY_LIMIT 256 | |
168 | ||
6eb396dc | 169 | static inline unsigned long scan_swap_map(struct swap_info_struct *si) |
1da177e4 | 170 | { |
ebebbbe9 | 171 | unsigned long offset; |
c60aa176 | 172 | unsigned long scan_base; |
7992fde7 | 173 | unsigned long last_in_cluster = 0; |
048c27fd | 174 | int latency_ration = LATENCY_LIMIT; |
7992fde7 | 175 | int found_free_cluster = 0; |
7dfad418 | 176 | |
886bb7e9 | 177 | /* |
7dfad418 HD |
178 | * We try to cluster swap pages by allocating them sequentially |
179 | * in swap. Once we've allocated SWAPFILE_CLUSTER pages this | |
180 | * way, however, we resort to first-free allocation, starting | |
181 | * a new cluster. This prevents us from scattering swap pages | |
182 | * all over the entire swap partition, so that we reduce | |
183 | * overall disk seek times between swap pages. -- sct | |
184 | * But we do now try to find an empty cluster. -Andrea | |
c60aa176 | 185 | * And we let swap pages go all over an SSD partition. Hugh |
7dfad418 HD |
186 | */ |
187 | ||
52b7efdb | 188 | si->flags += SWP_SCANNING; |
c60aa176 | 189 | scan_base = offset = si->cluster_next; |
ebebbbe9 HD |
190 | |
191 | if (unlikely(!si->cluster_nr--)) { | |
192 | if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { | |
193 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
194 | goto checks; | |
195 | } | |
7992fde7 HD |
196 | if (si->flags & SWP_DISCARDABLE) { |
197 | /* | |
198 | * Start range check on racing allocations, in case | |
199 | * they overlap the cluster we eventually decide on | |
200 | * (we scan without swap_lock to allow preemption). | |
201 | * It's hardly conceivable that cluster_nr could be | |
202 | * wrapped during our scan, but don't depend on it. | |
203 | */ | |
204 | if (si->lowest_alloc) | |
205 | goto checks; | |
206 | si->lowest_alloc = si->max; | |
207 | si->highest_alloc = 0; | |
208 | } | |
5d337b91 | 209 | spin_unlock(&swap_lock); |
7dfad418 | 210 | |
c60aa176 HD |
211 | /* |
212 | * If seek is expensive, start searching for new cluster from | |
213 | * start of partition, to minimize the span of allocated swap. | |
214 | * But if seek is cheap, search from our current position, so | |
215 | * that swap is allocated from all over the partition: if the | |
216 | * Flash Translation Layer only remaps within limited zones, | |
217 | * we don't want to wear out the first zone too quickly. | |
218 | */ | |
219 | if (!(si->flags & SWP_SOLIDSTATE)) | |
220 | scan_base = offset = si->lowest_bit; | |
7dfad418 HD |
221 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
222 | ||
223 | /* Locate the first empty (unaligned) cluster */ | |
224 | for (; last_in_cluster <= si->highest_bit; offset++) { | |
1da177e4 | 225 | if (si->swap_map[offset]) |
7dfad418 HD |
226 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
227 | else if (offset == last_in_cluster) { | |
5d337b91 | 228 | spin_lock(&swap_lock); |
ebebbbe9 HD |
229 | offset -= SWAPFILE_CLUSTER - 1; |
230 | si->cluster_next = offset; | |
231 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
7992fde7 | 232 | found_free_cluster = 1; |
ebebbbe9 | 233 | goto checks; |
1da177e4 | 234 | } |
048c27fd HD |
235 | if (unlikely(--latency_ration < 0)) { |
236 | cond_resched(); | |
237 | latency_ration = LATENCY_LIMIT; | |
238 | } | |
7dfad418 | 239 | } |
ebebbbe9 HD |
240 | |
241 | offset = si->lowest_bit; | |
c60aa176 HD |
242 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
243 | ||
244 | /* Locate the first empty (unaligned) cluster */ | |
245 | for (; last_in_cluster < scan_base; offset++) { | |
246 | if (si->swap_map[offset]) | |
247 | last_in_cluster = offset + SWAPFILE_CLUSTER; | |
248 | else if (offset == last_in_cluster) { | |
249 | spin_lock(&swap_lock); | |
250 | offset -= SWAPFILE_CLUSTER - 1; | |
251 | si->cluster_next = offset; | |
252 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
253 | found_free_cluster = 1; | |
254 | goto checks; | |
255 | } | |
256 | if (unlikely(--latency_ration < 0)) { | |
257 | cond_resched(); | |
258 | latency_ration = LATENCY_LIMIT; | |
259 | } | |
260 | } | |
261 | ||
262 | offset = scan_base; | |
5d337b91 | 263 | spin_lock(&swap_lock); |
ebebbbe9 | 264 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
7992fde7 | 265 | si->lowest_alloc = 0; |
1da177e4 | 266 | } |
7dfad418 | 267 | |
ebebbbe9 HD |
268 | checks: |
269 | if (!(si->flags & SWP_WRITEOK)) | |
52b7efdb | 270 | goto no_page; |
7dfad418 HD |
271 | if (!si->highest_bit) |
272 | goto no_page; | |
ebebbbe9 | 273 | if (offset > si->highest_bit) |
c60aa176 | 274 | scan_base = offset = si->lowest_bit; |
ebebbbe9 HD |
275 | if (si->swap_map[offset]) |
276 | goto scan; | |
277 | ||
278 | if (offset == si->lowest_bit) | |
279 | si->lowest_bit++; | |
280 | if (offset == si->highest_bit) | |
281 | si->highest_bit--; | |
282 | si->inuse_pages++; | |
283 | if (si->inuse_pages == si->pages) { | |
284 | si->lowest_bit = si->max; | |
285 | si->highest_bit = 0; | |
1da177e4 | 286 | } |
ebebbbe9 HD |
287 | si->swap_map[offset] = 1; |
288 | si->cluster_next = offset + 1; | |
289 | si->flags -= SWP_SCANNING; | |
7992fde7 HD |
290 | |
291 | if (si->lowest_alloc) { | |
292 | /* | |
293 | * Only set when SWP_DISCARDABLE, and there's a scan | |
294 | * for a free cluster in progress or just completed. | |
295 | */ | |
296 | if (found_free_cluster) { | |
297 | /* | |
298 | * To optimize wear-levelling, discard the | |
299 | * old data of the cluster, taking care not to | |
300 | * discard any of its pages that have already | |
301 | * been allocated by racing tasks (offset has | |
302 | * already stepped over any at the beginning). | |
303 | */ | |
304 | if (offset < si->highest_alloc && | |
305 | si->lowest_alloc <= last_in_cluster) | |
306 | last_in_cluster = si->lowest_alloc - 1; | |
307 | si->flags |= SWP_DISCARDING; | |
308 | spin_unlock(&swap_lock); | |
309 | ||
310 | if (offset < last_in_cluster) | |
311 | discard_swap_cluster(si, offset, | |
312 | last_in_cluster - offset + 1); | |
313 | ||
314 | spin_lock(&swap_lock); | |
315 | si->lowest_alloc = 0; | |
316 | si->flags &= ~SWP_DISCARDING; | |
317 | ||
318 | smp_mb(); /* wake_up_bit advises this */ | |
319 | wake_up_bit(&si->flags, ilog2(SWP_DISCARDING)); | |
320 | ||
321 | } else if (si->flags & SWP_DISCARDING) { | |
322 | /* | |
323 | * Delay using pages allocated by racing tasks | |
324 | * until the whole discard has been issued. We | |
325 | * could defer that delay until swap_writepage, | |
326 | * but it's easier to keep this self-contained. | |
327 | */ | |
328 | spin_unlock(&swap_lock); | |
329 | wait_on_bit(&si->flags, ilog2(SWP_DISCARDING), | |
330 | wait_for_discard, TASK_UNINTERRUPTIBLE); | |
331 | spin_lock(&swap_lock); | |
332 | } else { | |
333 | /* | |
334 | * Note pages allocated by racing tasks while | |
335 | * scan for a free cluster is in progress, so | |
336 | * that its final discard can exclude them. | |
337 | */ | |
338 | if (offset < si->lowest_alloc) | |
339 | si->lowest_alloc = offset; | |
340 | if (offset > si->highest_alloc) | |
341 | si->highest_alloc = offset; | |
342 | } | |
343 | } | |
ebebbbe9 | 344 | return offset; |
7dfad418 | 345 | |
ebebbbe9 | 346 | scan: |
5d337b91 | 347 | spin_unlock(&swap_lock); |
7dfad418 | 348 | while (++offset <= si->highest_bit) { |
52b7efdb | 349 | if (!si->swap_map[offset]) { |
5d337b91 | 350 | spin_lock(&swap_lock); |
52b7efdb HD |
351 | goto checks; |
352 | } | |
048c27fd HD |
353 | if (unlikely(--latency_ration < 0)) { |
354 | cond_resched(); | |
355 | latency_ration = LATENCY_LIMIT; | |
356 | } | |
7dfad418 | 357 | } |
c60aa176 HD |
358 | offset = si->lowest_bit; |
359 | while (++offset < scan_base) { | |
360 | if (!si->swap_map[offset]) { | |
361 | spin_lock(&swap_lock); | |
362 | goto checks; | |
363 | } | |
364 | if (unlikely(--latency_ration < 0)) { | |
365 | cond_resched(); | |
366 | latency_ration = LATENCY_LIMIT; | |
367 | } | |
368 | } | |
5d337b91 | 369 | spin_lock(&swap_lock); |
7dfad418 HD |
370 | |
371 | no_page: | |
52b7efdb | 372 | si->flags -= SWP_SCANNING; |
1da177e4 LT |
373 | return 0; |
374 | } | |
375 | ||
376 | swp_entry_t get_swap_page(void) | |
377 | { | |
fb4f88dc HD |
378 | struct swap_info_struct *si; |
379 | pgoff_t offset; | |
380 | int type, next; | |
381 | int wrapped = 0; | |
1da177e4 | 382 | |
5d337b91 | 383 | spin_lock(&swap_lock); |
1da177e4 | 384 | if (nr_swap_pages <= 0) |
fb4f88dc HD |
385 | goto noswap; |
386 | nr_swap_pages--; | |
387 | ||
388 | for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) { | |
389 | si = swap_info + type; | |
390 | next = si->next; | |
391 | if (next < 0 || | |
392 | (!wrapped && si->prio != swap_info[next].prio)) { | |
393 | next = swap_list.head; | |
394 | wrapped++; | |
1da177e4 | 395 | } |
fb4f88dc HD |
396 | |
397 | if (!si->highest_bit) | |
398 | continue; | |
399 | if (!(si->flags & SWP_WRITEOK)) | |
400 | continue; | |
401 | ||
402 | swap_list.next = next; | |
fb4f88dc | 403 | offset = scan_swap_map(si); |
5d337b91 HD |
404 | if (offset) { |
405 | spin_unlock(&swap_lock); | |
fb4f88dc | 406 | return swp_entry(type, offset); |
5d337b91 | 407 | } |
fb4f88dc | 408 | next = swap_list.next; |
1da177e4 | 409 | } |
fb4f88dc HD |
410 | |
411 | nr_swap_pages++; | |
412 | noswap: | |
5d337b91 | 413 | spin_unlock(&swap_lock); |
fb4f88dc | 414 | return (swp_entry_t) {0}; |
1da177e4 LT |
415 | } |
416 | ||
3a291a20 RW |
417 | swp_entry_t get_swap_page_of_type(int type) |
418 | { | |
419 | struct swap_info_struct *si; | |
420 | pgoff_t offset; | |
421 | ||
422 | spin_lock(&swap_lock); | |
423 | si = swap_info + type; | |
424 | if (si->flags & SWP_WRITEOK) { | |
425 | nr_swap_pages--; | |
426 | offset = scan_swap_map(si); | |
427 | if (offset) { | |
428 | spin_unlock(&swap_lock); | |
429 | return swp_entry(type, offset); | |
430 | } | |
431 | nr_swap_pages++; | |
432 | } | |
433 | spin_unlock(&swap_lock); | |
434 | return (swp_entry_t) {0}; | |
435 | } | |
436 | ||
1da177e4 LT |
437 | static struct swap_info_struct * swap_info_get(swp_entry_t entry) |
438 | { | |
439 | struct swap_info_struct * p; | |
440 | unsigned long offset, type; | |
441 | ||
442 | if (!entry.val) | |
443 | goto out; | |
444 | type = swp_type(entry); | |
445 | if (type >= nr_swapfiles) | |
446 | goto bad_nofile; | |
447 | p = & swap_info[type]; | |
448 | if (!(p->flags & SWP_USED)) | |
449 | goto bad_device; | |
450 | offset = swp_offset(entry); | |
451 | if (offset >= p->max) | |
452 | goto bad_offset; | |
453 | if (!p->swap_map[offset]) | |
454 | goto bad_free; | |
5d337b91 | 455 | spin_lock(&swap_lock); |
1da177e4 LT |
456 | return p; |
457 | ||
458 | bad_free: | |
459 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val); | |
460 | goto out; | |
461 | bad_offset: | |
462 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val); | |
463 | goto out; | |
464 | bad_device: | |
465 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val); | |
466 | goto out; | |
467 | bad_nofile: | |
468 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val); | |
469 | out: | |
470 | return NULL; | |
886bb7e9 | 471 | } |
1da177e4 | 472 | |
1da177e4 LT |
473 | static int swap_entry_free(struct swap_info_struct *p, unsigned long offset) |
474 | { | |
475 | int count = p->swap_map[offset]; | |
476 | ||
477 | if (count < SWAP_MAP_MAX) { | |
478 | count--; | |
479 | p->swap_map[offset] = count; | |
480 | if (!count) { | |
481 | if (offset < p->lowest_bit) | |
482 | p->lowest_bit = offset; | |
483 | if (offset > p->highest_bit) | |
484 | p->highest_bit = offset; | |
89d09a2c HD |
485 | if (p->prio > swap_info[swap_list.next].prio) |
486 | swap_list.next = p - swap_info; | |
1da177e4 LT |
487 | nr_swap_pages++; |
488 | p->inuse_pages--; | |
489 | } | |
490 | } | |
491 | return count; | |
492 | } | |
493 | ||
494 | /* | |
495 | * Caller has made sure that the swapdevice corresponding to entry | |
496 | * is still around or has not been recycled. | |
497 | */ | |
498 | void swap_free(swp_entry_t entry) | |
499 | { | |
500 | struct swap_info_struct * p; | |
501 | ||
502 | p = swap_info_get(entry); | |
503 | if (p) { | |
504 | swap_entry_free(p, swp_offset(entry)); | |
5d337b91 | 505 | spin_unlock(&swap_lock); |
1da177e4 LT |
506 | } |
507 | } | |
508 | ||
509 | /* | |
c475a8ab | 510 | * How many references to page are currently swapped out? |
1da177e4 | 511 | */ |
c475a8ab | 512 | static inline int page_swapcount(struct page *page) |
1da177e4 | 513 | { |
c475a8ab HD |
514 | int count = 0; |
515 | struct swap_info_struct *p; | |
1da177e4 LT |
516 | swp_entry_t entry; |
517 | ||
4c21e2f2 | 518 | entry.val = page_private(page); |
1da177e4 LT |
519 | p = swap_info_get(entry); |
520 | if (p) { | |
c475a8ab HD |
521 | /* Subtract the 1 for the swap cache itself */ |
522 | count = p->swap_map[swp_offset(entry)] - 1; | |
5d337b91 | 523 | spin_unlock(&swap_lock); |
1da177e4 | 524 | } |
c475a8ab | 525 | return count; |
1da177e4 LT |
526 | } |
527 | ||
528 | /* | |
7b1fe597 HD |
529 | * We can write to an anon page without COW if there are no other references |
530 | * to it. And as a side-effect, free up its swap: because the old content | |
531 | * on disk will never be read, and seeking back there to write new content | |
532 | * later would only waste time away from clustering. | |
1da177e4 | 533 | */ |
7b1fe597 | 534 | int reuse_swap_page(struct page *page) |
1da177e4 | 535 | { |
c475a8ab HD |
536 | int count; |
537 | ||
51726b12 | 538 | VM_BUG_ON(!PageLocked(page)); |
c475a8ab | 539 | count = page_mapcount(page); |
7b1fe597 | 540 | if (count <= 1 && PageSwapCache(page)) { |
c475a8ab | 541 | count += page_swapcount(page); |
7b1fe597 HD |
542 | if (count == 1 && !PageWriteback(page)) { |
543 | delete_from_swap_cache(page); | |
544 | SetPageDirty(page); | |
545 | } | |
546 | } | |
c475a8ab | 547 | return count == 1; |
1da177e4 LT |
548 | } |
549 | ||
550 | /* | |
a2c43eed HD |
551 | * If swap is getting full, or if there are no more mappings of this page, |
552 | * then try_to_free_swap is called to free its swap space. | |
1da177e4 | 553 | */ |
a2c43eed | 554 | int try_to_free_swap(struct page *page) |
1da177e4 | 555 | { |
51726b12 | 556 | VM_BUG_ON(!PageLocked(page)); |
1da177e4 LT |
557 | |
558 | if (!PageSwapCache(page)) | |
559 | return 0; | |
560 | if (PageWriteback(page)) | |
561 | return 0; | |
a2c43eed | 562 | if (page_swapcount(page)) |
1da177e4 LT |
563 | return 0; |
564 | ||
a2c43eed HD |
565 | delete_from_swap_cache(page); |
566 | SetPageDirty(page); | |
567 | return 1; | |
68a22394 RR |
568 | } |
569 | ||
1da177e4 LT |
570 | /* |
571 | * Free the swap entry like above, but also try to | |
572 | * free the page cache entry if it is the last user. | |
573 | */ | |
574 | void free_swap_and_cache(swp_entry_t entry) | |
575 | { | |
576 | struct swap_info_struct * p; | |
577 | struct page *page = NULL; | |
578 | ||
0697212a CL |
579 | if (is_migration_entry(entry)) |
580 | return; | |
581 | ||
1da177e4 LT |
582 | p = swap_info_get(entry); |
583 | if (p) { | |
93fac704 NP |
584 | if (swap_entry_free(p, swp_offset(entry)) == 1) { |
585 | page = find_get_page(&swapper_space, entry.val); | |
8413ac9d | 586 | if (page && !trylock_page(page)) { |
93fac704 NP |
587 | page_cache_release(page); |
588 | page = NULL; | |
589 | } | |
590 | } | |
5d337b91 | 591 | spin_unlock(&swap_lock); |
1da177e4 LT |
592 | } |
593 | if (page) { | |
a2c43eed HD |
594 | /* |
595 | * Not mapped elsewhere, or swap space full? Free it! | |
596 | * Also recheck PageSwapCache now page is locked (above). | |
597 | */ | |
93fac704 | 598 | if (PageSwapCache(page) && !PageWriteback(page) && |
a2c43eed | 599 | (!page_mapped(page) || vm_swap_full())) { |
1da177e4 LT |
600 | delete_from_swap_cache(page); |
601 | SetPageDirty(page); | |
602 | } | |
603 | unlock_page(page); | |
604 | page_cache_release(page); | |
605 | } | |
606 | } | |
607 | ||
b0cb1a19 | 608 | #ifdef CONFIG_HIBERNATION |
f577eb30 | 609 | /* |
915bae9e | 610 | * Find the swap type that corresponds to given device (if any). |
f577eb30 | 611 | * |
915bae9e RW |
612 | * @offset - number of the PAGE_SIZE-sized block of the device, starting |
613 | * from 0, in which the swap header is expected to be located. | |
614 | * | |
615 | * This is needed for the suspend to disk (aka swsusp). | |
f577eb30 | 616 | */ |
7bf23687 | 617 | int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) |
f577eb30 | 618 | { |
915bae9e | 619 | struct block_device *bdev = NULL; |
f577eb30 RW |
620 | int i; |
621 | ||
915bae9e RW |
622 | if (device) |
623 | bdev = bdget(device); | |
624 | ||
f577eb30 RW |
625 | spin_lock(&swap_lock); |
626 | for (i = 0; i < nr_swapfiles; i++) { | |
915bae9e | 627 | struct swap_info_struct *sis = swap_info + i; |
f577eb30 | 628 | |
915bae9e | 629 | if (!(sis->flags & SWP_WRITEOK)) |
f577eb30 | 630 | continue; |
b6b5bce3 | 631 | |
915bae9e | 632 | if (!bdev) { |
7bf23687 RW |
633 | if (bdev_p) |
634 | *bdev_p = sis->bdev; | |
635 | ||
6e1819d6 RW |
636 | spin_unlock(&swap_lock); |
637 | return i; | |
638 | } | |
915bae9e RW |
639 | if (bdev == sis->bdev) { |
640 | struct swap_extent *se; | |
641 | ||
642 | se = list_entry(sis->extent_list.next, | |
643 | struct swap_extent, list); | |
644 | if (se->start_block == offset) { | |
7bf23687 RW |
645 | if (bdev_p) |
646 | *bdev_p = sis->bdev; | |
647 | ||
915bae9e RW |
648 | spin_unlock(&swap_lock); |
649 | bdput(bdev); | |
650 | return i; | |
651 | } | |
f577eb30 RW |
652 | } |
653 | } | |
654 | spin_unlock(&swap_lock); | |
915bae9e RW |
655 | if (bdev) |
656 | bdput(bdev); | |
657 | ||
f577eb30 RW |
658 | return -ENODEV; |
659 | } | |
660 | ||
661 | /* | |
662 | * Return either the total number of swap pages of given type, or the number | |
663 | * of free pages of that type (depending on @free) | |
664 | * | |
665 | * This is needed for software suspend | |
666 | */ | |
667 | unsigned int count_swap_pages(int type, int free) | |
668 | { | |
669 | unsigned int n = 0; | |
670 | ||
671 | if (type < nr_swapfiles) { | |
672 | spin_lock(&swap_lock); | |
673 | if (swap_info[type].flags & SWP_WRITEOK) { | |
674 | n = swap_info[type].pages; | |
675 | if (free) | |
676 | n -= swap_info[type].inuse_pages; | |
677 | } | |
678 | spin_unlock(&swap_lock); | |
679 | } | |
680 | return n; | |
681 | } | |
682 | #endif | |
683 | ||
1da177e4 | 684 | /* |
72866f6f HD |
685 | * No need to decide whether this PTE shares the swap entry with others, |
686 | * just let do_wp_page work it out if a write is requested later - to | |
687 | * force COW, vm_page_prot omits write permission from any private vma. | |
1da177e4 | 688 | */ |
044d66c1 | 689 | static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
1da177e4 LT |
690 | unsigned long addr, swp_entry_t entry, struct page *page) |
691 | { | |
044d66c1 HD |
692 | spinlock_t *ptl; |
693 | pte_t *pte; | |
694 | int ret = 1; | |
695 | ||
e1a1cd59 | 696 | if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL)) |
044d66c1 HD |
697 | ret = -ENOMEM; |
698 | ||
699 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); | |
700 | if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) { | |
701 | if (ret > 0) | |
702 | mem_cgroup_uncharge_page(page); | |
703 | ret = 0; | |
704 | goto out; | |
705 | } | |
8a9f3ccd | 706 | |
4294621f | 707 | inc_mm_counter(vma->vm_mm, anon_rss); |
1da177e4 LT |
708 | get_page(page); |
709 | set_pte_at(vma->vm_mm, addr, pte, | |
710 | pte_mkold(mk_pte(page, vma->vm_page_prot))); | |
711 | page_add_anon_rmap(page, vma, addr); | |
712 | swap_free(entry); | |
713 | /* | |
714 | * Move the page to the active list so it is not | |
715 | * immediately swapped out again after swapon. | |
716 | */ | |
717 | activate_page(page); | |
044d66c1 HD |
718 | out: |
719 | pte_unmap_unlock(pte, ptl); | |
720 | return ret; | |
1da177e4 LT |
721 | } |
722 | ||
723 | static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, | |
724 | unsigned long addr, unsigned long end, | |
725 | swp_entry_t entry, struct page *page) | |
726 | { | |
1da177e4 | 727 | pte_t swp_pte = swp_entry_to_pte(entry); |
705e87c0 | 728 | pte_t *pte; |
8a9f3ccd | 729 | int ret = 0; |
1da177e4 | 730 | |
044d66c1 HD |
731 | /* |
732 | * We don't actually need pte lock while scanning for swp_pte: since | |
733 | * we hold page lock and mmap_sem, swp_pte cannot be inserted into the | |
734 | * page table while we're scanning; though it could get zapped, and on | |
735 | * some architectures (e.g. x86_32 with PAE) we might catch a glimpse | |
736 | * of unmatched parts which look like swp_pte, so unuse_pte must | |
737 | * recheck under pte lock. Scanning without pte lock lets it be | |
738 | * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE. | |
739 | */ | |
740 | pte = pte_offset_map(pmd, addr); | |
1da177e4 LT |
741 | do { |
742 | /* | |
743 | * swapoff spends a _lot_ of time in this loop! | |
744 | * Test inline before going to call unuse_pte. | |
745 | */ | |
746 | if (unlikely(pte_same(*pte, swp_pte))) { | |
044d66c1 HD |
747 | pte_unmap(pte); |
748 | ret = unuse_pte(vma, pmd, addr, entry, page); | |
749 | if (ret) | |
750 | goto out; | |
751 | pte = pte_offset_map(pmd, addr); | |
1da177e4 LT |
752 | } |
753 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
044d66c1 HD |
754 | pte_unmap(pte - 1); |
755 | out: | |
8a9f3ccd | 756 | return ret; |
1da177e4 LT |
757 | } |
758 | ||
759 | static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, | |
760 | unsigned long addr, unsigned long end, | |
761 | swp_entry_t entry, struct page *page) | |
762 | { | |
763 | pmd_t *pmd; | |
764 | unsigned long next; | |
8a9f3ccd | 765 | int ret; |
1da177e4 LT |
766 | |
767 | pmd = pmd_offset(pud, addr); | |
768 | do { | |
769 | next = pmd_addr_end(addr, end); | |
770 | if (pmd_none_or_clear_bad(pmd)) | |
771 | continue; | |
8a9f3ccd BS |
772 | ret = unuse_pte_range(vma, pmd, addr, next, entry, page); |
773 | if (ret) | |
774 | return ret; | |
1da177e4 LT |
775 | } while (pmd++, addr = next, addr != end); |
776 | return 0; | |
777 | } | |
778 | ||
779 | static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd, | |
780 | unsigned long addr, unsigned long end, | |
781 | swp_entry_t entry, struct page *page) | |
782 | { | |
783 | pud_t *pud; | |
784 | unsigned long next; | |
8a9f3ccd | 785 | int ret; |
1da177e4 LT |
786 | |
787 | pud = pud_offset(pgd, addr); | |
788 | do { | |
789 | next = pud_addr_end(addr, end); | |
790 | if (pud_none_or_clear_bad(pud)) | |
791 | continue; | |
8a9f3ccd BS |
792 | ret = unuse_pmd_range(vma, pud, addr, next, entry, page); |
793 | if (ret) | |
794 | return ret; | |
1da177e4 LT |
795 | } while (pud++, addr = next, addr != end); |
796 | return 0; | |
797 | } | |
798 | ||
799 | static int unuse_vma(struct vm_area_struct *vma, | |
800 | swp_entry_t entry, struct page *page) | |
801 | { | |
802 | pgd_t *pgd; | |
803 | unsigned long addr, end, next; | |
8a9f3ccd | 804 | int ret; |
1da177e4 LT |
805 | |
806 | if (page->mapping) { | |
807 | addr = page_address_in_vma(page, vma); | |
808 | if (addr == -EFAULT) | |
809 | return 0; | |
810 | else | |
811 | end = addr + PAGE_SIZE; | |
812 | } else { | |
813 | addr = vma->vm_start; | |
814 | end = vma->vm_end; | |
815 | } | |
816 | ||
817 | pgd = pgd_offset(vma->vm_mm, addr); | |
818 | do { | |
819 | next = pgd_addr_end(addr, end); | |
820 | if (pgd_none_or_clear_bad(pgd)) | |
821 | continue; | |
8a9f3ccd BS |
822 | ret = unuse_pud_range(vma, pgd, addr, next, entry, page); |
823 | if (ret) | |
824 | return ret; | |
1da177e4 LT |
825 | } while (pgd++, addr = next, addr != end); |
826 | return 0; | |
827 | } | |
828 | ||
829 | static int unuse_mm(struct mm_struct *mm, | |
830 | swp_entry_t entry, struct page *page) | |
831 | { | |
832 | struct vm_area_struct *vma; | |
8a9f3ccd | 833 | int ret = 0; |
1da177e4 LT |
834 | |
835 | if (!down_read_trylock(&mm->mmap_sem)) { | |
836 | /* | |
7d03431c FLVC |
837 | * Activate page so shrink_inactive_list is unlikely to unmap |
838 | * its ptes while lock is dropped, so swapoff can make progress. | |
1da177e4 | 839 | */ |
c475a8ab | 840 | activate_page(page); |
1da177e4 LT |
841 | unlock_page(page); |
842 | down_read(&mm->mmap_sem); | |
843 | lock_page(page); | |
844 | } | |
1da177e4 | 845 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
8a9f3ccd | 846 | if (vma->anon_vma && (ret = unuse_vma(vma, entry, page))) |
1da177e4 LT |
847 | break; |
848 | } | |
1da177e4 | 849 | up_read(&mm->mmap_sem); |
8a9f3ccd | 850 | return (ret < 0)? ret: 0; |
1da177e4 LT |
851 | } |
852 | ||
853 | /* | |
854 | * Scan swap_map from current position to next entry still in use. | |
855 | * Recycle to start on reaching the end, returning 0 when empty. | |
856 | */ | |
6eb396dc HD |
857 | static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
858 | unsigned int prev) | |
1da177e4 | 859 | { |
6eb396dc HD |
860 | unsigned int max = si->max; |
861 | unsigned int i = prev; | |
1da177e4 LT |
862 | int count; |
863 | ||
864 | /* | |
5d337b91 | 865 | * No need for swap_lock here: we're just looking |
1da177e4 LT |
866 | * for whether an entry is in use, not modifying it; false |
867 | * hits are okay, and sys_swapoff() has already prevented new | |
5d337b91 | 868 | * allocations from this area (while holding swap_lock). |
1da177e4 LT |
869 | */ |
870 | for (;;) { | |
871 | if (++i >= max) { | |
872 | if (!prev) { | |
873 | i = 0; | |
874 | break; | |
875 | } | |
876 | /* | |
877 | * No entries in use at top of swap_map, | |
878 | * loop back to start and recheck there. | |
879 | */ | |
880 | max = prev + 1; | |
881 | prev = 0; | |
882 | i = 1; | |
883 | } | |
884 | count = si->swap_map[i]; | |
885 | if (count && count != SWAP_MAP_BAD) | |
886 | break; | |
887 | } | |
888 | return i; | |
889 | } | |
890 | ||
891 | /* | |
892 | * We completely avoid races by reading each swap page in advance, | |
893 | * and then search for the process using it. All the necessary | |
894 | * page table adjustments can then be made atomically. | |
895 | */ | |
896 | static int try_to_unuse(unsigned int type) | |
897 | { | |
898 | struct swap_info_struct * si = &swap_info[type]; | |
899 | struct mm_struct *start_mm; | |
900 | unsigned short *swap_map; | |
901 | unsigned short swcount; | |
902 | struct page *page; | |
903 | swp_entry_t entry; | |
6eb396dc | 904 | unsigned int i = 0; |
1da177e4 LT |
905 | int retval = 0; |
906 | int reset_overflow = 0; | |
907 | int shmem; | |
908 | ||
909 | /* | |
910 | * When searching mms for an entry, a good strategy is to | |
911 | * start at the first mm we freed the previous entry from | |
912 | * (though actually we don't notice whether we or coincidence | |
913 | * freed the entry). Initialize this start_mm with a hold. | |
914 | * | |
915 | * A simpler strategy would be to start at the last mm we | |
916 | * freed the previous entry from; but that would take less | |
917 | * advantage of mmlist ordering, which clusters forked mms | |
918 | * together, child after parent. If we race with dup_mmap(), we | |
919 | * prefer to resolve parent before child, lest we miss entries | |
920 | * duplicated after we scanned child: using last mm would invert | |
921 | * that. Though it's only a serious concern when an overflowed | |
922 | * swap count is reset from SWAP_MAP_MAX, preventing a rescan. | |
923 | */ | |
924 | start_mm = &init_mm; | |
925 | atomic_inc(&init_mm.mm_users); | |
926 | ||
927 | /* | |
928 | * Keep on scanning until all entries have gone. Usually, | |
929 | * one pass through swap_map is enough, but not necessarily: | |
930 | * there are races when an instance of an entry might be missed. | |
931 | */ | |
932 | while ((i = find_next_to_unuse(si, i)) != 0) { | |
933 | if (signal_pending(current)) { | |
934 | retval = -EINTR; | |
935 | break; | |
936 | } | |
937 | ||
886bb7e9 | 938 | /* |
1da177e4 LT |
939 | * Get a page for the entry, using the existing swap |
940 | * cache page if there is one. Otherwise, get a clean | |
886bb7e9 | 941 | * page and read the swap into it. |
1da177e4 LT |
942 | */ |
943 | swap_map = &si->swap_map[i]; | |
944 | entry = swp_entry(type, i); | |
02098fea HD |
945 | page = read_swap_cache_async(entry, |
946 | GFP_HIGHUSER_MOVABLE, NULL, 0); | |
1da177e4 LT |
947 | if (!page) { |
948 | /* | |
949 | * Either swap_duplicate() failed because entry | |
950 | * has been freed independently, and will not be | |
951 | * reused since sys_swapoff() already disabled | |
952 | * allocation from here, or alloc_page() failed. | |
953 | */ | |
954 | if (!*swap_map) | |
955 | continue; | |
956 | retval = -ENOMEM; | |
957 | break; | |
958 | } | |
959 | ||
960 | /* | |
961 | * Don't hold on to start_mm if it looks like exiting. | |
962 | */ | |
963 | if (atomic_read(&start_mm->mm_users) == 1) { | |
964 | mmput(start_mm); | |
965 | start_mm = &init_mm; | |
966 | atomic_inc(&init_mm.mm_users); | |
967 | } | |
968 | ||
969 | /* | |
970 | * Wait for and lock page. When do_swap_page races with | |
971 | * try_to_unuse, do_swap_page can handle the fault much | |
972 | * faster than try_to_unuse can locate the entry. This | |
973 | * apparently redundant "wait_on_page_locked" lets try_to_unuse | |
974 | * defer to do_swap_page in such a case - in some tests, | |
975 | * do_swap_page and try_to_unuse repeatedly compete. | |
976 | */ | |
977 | wait_on_page_locked(page); | |
978 | wait_on_page_writeback(page); | |
979 | lock_page(page); | |
980 | wait_on_page_writeback(page); | |
981 | ||
982 | /* | |
983 | * Remove all references to entry. | |
984 | * Whenever we reach init_mm, there's no address space | |
985 | * to search, but use it as a reminder to search shmem. | |
986 | */ | |
987 | shmem = 0; | |
988 | swcount = *swap_map; | |
989 | if (swcount > 1) { | |
990 | if (start_mm == &init_mm) | |
991 | shmem = shmem_unuse(entry, page); | |
992 | else | |
993 | retval = unuse_mm(start_mm, entry, page); | |
994 | } | |
995 | if (*swap_map > 1) { | |
996 | int set_start_mm = (*swap_map >= swcount); | |
997 | struct list_head *p = &start_mm->mmlist; | |
998 | struct mm_struct *new_start_mm = start_mm; | |
999 | struct mm_struct *prev_mm = start_mm; | |
1000 | struct mm_struct *mm; | |
1001 | ||
1002 | atomic_inc(&new_start_mm->mm_users); | |
1003 | atomic_inc(&prev_mm->mm_users); | |
1004 | spin_lock(&mmlist_lock); | |
2e0e26c7 | 1005 | while (*swap_map > 1 && !retval && !shmem && |
1da177e4 LT |
1006 | (p = p->next) != &start_mm->mmlist) { |
1007 | mm = list_entry(p, struct mm_struct, mmlist); | |
70af7c5c | 1008 | if (!atomic_inc_not_zero(&mm->mm_users)) |
1da177e4 | 1009 | continue; |
1da177e4 LT |
1010 | spin_unlock(&mmlist_lock); |
1011 | mmput(prev_mm); | |
1012 | prev_mm = mm; | |
1013 | ||
1014 | cond_resched(); | |
1015 | ||
1016 | swcount = *swap_map; | |
1017 | if (swcount <= 1) | |
1018 | ; | |
1019 | else if (mm == &init_mm) { | |
1020 | set_start_mm = 1; | |
1021 | shmem = shmem_unuse(entry, page); | |
1022 | } else | |
1023 | retval = unuse_mm(mm, entry, page); | |
1024 | if (set_start_mm && *swap_map < swcount) { | |
1025 | mmput(new_start_mm); | |
1026 | atomic_inc(&mm->mm_users); | |
1027 | new_start_mm = mm; | |
1028 | set_start_mm = 0; | |
1029 | } | |
1030 | spin_lock(&mmlist_lock); | |
1031 | } | |
1032 | spin_unlock(&mmlist_lock); | |
1033 | mmput(prev_mm); | |
1034 | mmput(start_mm); | |
1035 | start_mm = new_start_mm; | |
1036 | } | |
2e0e26c7 HD |
1037 | if (shmem) { |
1038 | /* page has already been unlocked and released */ | |
1039 | if (shmem > 0) | |
1040 | continue; | |
1041 | retval = shmem; | |
1042 | break; | |
1043 | } | |
1da177e4 LT |
1044 | if (retval) { |
1045 | unlock_page(page); | |
1046 | page_cache_release(page); | |
1047 | break; | |
1048 | } | |
1049 | ||
1050 | /* | |
1051 | * How could swap count reach 0x7fff when the maximum | |
1052 | * pid is 0x7fff, and there's no way to repeat a swap | |
1053 | * page within an mm (except in shmem, where it's the | |
1054 | * shared object which takes the reference count)? | |
1055 | * We believe SWAP_MAP_MAX cannot occur in Linux 2.4. | |
1056 | * | |
1057 | * If that's wrong, then we should worry more about | |
1058 | * exit_mmap() and do_munmap() cases described above: | |
1059 | * we might be resetting SWAP_MAP_MAX too early here. | |
1060 | * We know "Undead"s can happen, they're okay, so don't | |
1061 | * report them; but do report if we reset SWAP_MAP_MAX. | |
1062 | */ | |
1063 | if (*swap_map == SWAP_MAP_MAX) { | |
5d337b91 | 1064 | spin_lock(&swap_lock); |
1da177e4 | 1065 | *swap_map = 1; |
5d337b91 | 1066 | spin_unlock(&swap_lock); |
1da177e4 LT |
1067 | reset_overflow = 1; |
1068 | } | |
1069 | ||
1070 | /* | |
1071 | * If a reference remains (rare), we would like to leave | |
1072 | * the page in the swap cache; but try_to_unmap could | |
1073 | * then re-duplicate the entry once we drop page lock, | |
1074 | * so we might loop indefinitely; also, that page could | |
1075 | * not be swapped out to other storage meanwhile. So: | |
1076 | * delete from cache even if there's another reference, | |
1077 | * after ensuring that the data has been saved to disk - | |
1078 | * since if the reference remains (rarer), it will be | |
1079 | * read from disk into another page. Splitting into two | |
1080 | * pages would be incorrect if swap supported "shared | |
1081 | * private" pages, but they are handled by tmpfs files. | |
1da177e4 LT |
1082 | */ |
1083 | if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) { | |
1084 | struct writeback_control wbc = { | |
1085 | .sync_mode = WB_SYNC_NONE, | |
1086 | }; | |
1087 | ||
1088 | swap_writepage(page, &wbc); | |
1089 | lock_page(page); | |
1090 | wait_on_page_writeback(page); | |
1091 | } | |
68bdc8d6 HD |
1092 | |
1093 | /* | |
1094 | * It is conceivable that a racing task removed this page from | |
1095 | * swap cache just before we acquired the page lock at the top, | |
1096 | * or while we dropped it in unuse_mm(). The page might even | |
1097 | * be back in swap cache on another swap area: that we must not | |
1098 | * delete, since it may not have been written out to swap yet. | |
1099 | */ | |
1100 | if (PageSwapCache(page) && | |
1101 | likely(page_private(page) == entry.val)) | |
2e0e26c7 | 1102 | delete_from_swap_cache(page); |
1da177e4 LT |
1103 | |
1104 | /* | |
1105 | * So we could skip searching mms once swap count went | |
1106 | * to 1, we did not mark any present ptes as dirty: must | |
2706a1b8 | 1107 | * mark page dirty so shrink_page_list will preserve it. |
1da177e4 LT |
1108 | */ |
1109 | SetPageDirty(page); | |
1110 | unlock_page(page); | |
1111 | page_cache_release(page); | |
1112 | ||
1113 | /* | |
1114 | * Make sure that we aren't completely killing | |
1115 | * interactive performance. | |
1116 | */ | |
1117 | cond_resched(); | |
1118 | } | |
1119 | ||
1120 | mmput(start_mm); | |
1121 | if (reset_overflow) { | |
1122 | printk(KERN_WARNING "swapoff: cleared swap entry overflow\n"); | |
1123 | swap_overflow = 0; | |
1124 | } | |
1125 | return retval; | |
1126 | } | |
1127 | ||
1128 | /* | |
5d337b91 HD |
1129 | * After a successful try_to_unuse, if no swap is now in use, we know |
1130 | * we can empty the mmlist. swap_lock must be held on entry and exit. | |
1131 | * Note that mmlist_lock nests inside swap_lock, and an mm must be | |
1da177e4 LT |
1132 | * added to the mmlist just after page_duplicate - before would be racy. |
1133 | */ | |
1134 | static void drain_mmlist(void) | |
1135 | { | |
1136 | struct list_head *p, *next; | |
1137 | unsigned int i; | |
1138 | ||
1139 | for (i = 0; i < nr_swapfiles; i++) | |
1140 | if (swap_info[i].inuse_pages) | |
1141 | return; | |
1142 | spin_lock(&mmlist_lock); | |
1143 | list_for_each_safe(p, next, &init_mm.mmlist) | |
1144 | list_del_init(p); | |
1145 | spin_unlock(&mmlist_lock); | |
1146 | } | |
1147 | ||
1148 | /* | |
1149 | * Use this swapdev's extent info to locate the (PAGE_SIZE) block which | |
1150 | * corresponds to page offset `offset'. | |
1151 | */ | |
1152 | sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset) | |
1153 | { | |
1154 | struct swap_extent *se = sis->curr_swap_extent; | |
1155 | struct swap_extent *start_se = se; | |
1156 | ||
1157 | for ( ; ; ) { | |
1158 | struct list_head *lh; | |
1159 | ||
1160 | if (se->start_page <= offset && | |
1161 | offset < (se->start_page + se->nr_pages)) { | |
1162 | return se->start_block + (offset - se->start_page); | |
1163 | } | |
11d31886 | 1164 | lh = se->list.next; |
1da177e4 | 1165 | if (lh == &sis->extent_list) |
11d31886 | 1166 | lh = lh->next; |
1da177e4 LT |
1167 | se = list_entry(lh, struct swap_extent, list); |
1168 | sis->curr_swap_extent = se; | |
1169 | BUG_ON(se == start_se); /* It *must* be present */ | |
1170 | } | |
1171 | } | |
1172 | ||
b0cb1a19 | 1173 | #ifdef CONFIG_HIBERNATION |
3aef83e0 RW |
1174 | /* |
1175 | * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev | |
1176 | * corresponding to given index in swap_info (swap type). | |
1177 | */ | |
1178 | sector_t swapdev_block(int swap_type, pgoff_t offset) | |
1179 | { | |
1180 | struct swap_info_struct *sis; | |
1181 | ||
1182 | if (swap_type >= nr_swapfiles) | |
1183 | return 0; | |
1184 | ||
1185 | sis = swap_info + swap_type; | |
1186 | return (sis->flags & SWP_WRITEOK) ? map_swap_page(sis, offset) : 0; | |
1187 | } | |
b0cb1a19 | 1188 | #endif /* CONFIG_HIBERNATION */ |
3aef83e0 | 1189 | |
1da177e4 LT |
1190 | /* |
1191 | * Free all of a swapdev's extent information | |
1192 | */ | |
1193 | static void destroy_swap_extents(struct swap_info_struct *sis) | |
1194 | { | |
1195 | while (!list_empty(&sis->extent_list)) { | |
1196 | struct swap_extent *se; | |
1197 | ||
1198 | se = list_entry(sis->extent_list.next, | |
1199 | struct swap_extent, list); | |
1200 | list_del(&se->list); | |
1201 | kfree(se); | |
1202 | } | |
1da177e4 LT |
1203 | } |
1204 | ||
1205 | /* | |
1206 | * Add a block range (and the corresponding page range) into this swapdev's | |
11d31886 | 1207 | * extent list. The extent list is kept sorted in page order. |
1da177e4 | 1208 | * |
11d31886 | 1209 | * This function rather assumes that it is called in ascending page order. |
1da177e4 LT |
1210 | */ |
1211 | static int | |
1212 | add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, | |
1213 | unsigned long nr_pages, sector_t start_block) | |
1214 | { | |
1215 | struct swap_extent *se; | |
1216 | struct swap_extent *new_se; | |
1217 | struct list_head *lh; | |
1218 | ||
11d31886 HD |
1219 | lh = sis->extent_list.prev; /* The highest page extent */ |
1220 | if (lh != &sis->extent_list) { | |
1da177e4 | 1221 | se = list_entry(lh, struct swap_extent, list); |
11d31886 HD |
1222 | BUG_ON(se->start_page + se->nr_pages != start_page); |
1223 | if (se->start_block + se->nr_pages == start_block) { | |
1da177e4 LT |
1224 | /* Merge it */ |
1225 | se->nr_pages += nr_pages; | |
1226 | return 0; | |
1227 | } | |
1da177e4 LT |
1228 | } |
1229 | ||
1230 | /* | |
1231 | * No merge. Insert a new extent, preserving ordering. | |
1232 | */ | |
1233 | new_se = kmalloc(sizeof(*se), GFP_KERNEL); | |
1234 | if (new_se == NULL) | |
1235 | return -ENOMEM; | |
1236 | new_se->start_page = start_page; | |
1237 | new_se->nr_pages = nr_pages; | |
1238 | new_se->start_block = start_block; | |
1239 | ||
11d31886 | 1240 | list_add_tail(&new_se->list, &sis->extent_list); |
53092a74 | 1241 | return 1; |
1da177e4 LT |
1242 | } |
1243 | ||
1244 | /* | |
1245 | * A `swap extent' is a simple thing which maps a contiguous range of pages | |
1246 | * onto a contiguous range of disk blocks. An ordered list of swap extents | |
1247 | * is built at swapon time and is then used at swap_writepage/swap_readpage | |
1248 | * time for locating where on disk a page belongs. | |
1249 | * | |
1250 | * If the swapfile is an S_ISBLK block device, a single extent is installed. | |
1251 | * This is done so that the main operating code can treat S_ISBLK and S_ISREG | |
1252 | * swap files identically. | |
1253 | * | |
1254 | * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap | |
1255 | * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK | |
1256 | * swapfiles are handled *identically* after swapon time. | |
1257 | * | |
1258 | * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks | |
1259 | * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If | |
1260 | * some stray blocks are found which do not fall within the PAGE_SIZE alignment | |
1261 | * requirements, they are simply tossed out - we will never use those blocks | |
1262 | * for swapping. | |
1263 | * | |
b0d9bcd4 | 1264 | * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This |
1da177e4 LT |
1265 | * prevents root from shooting her foot off by ftruncating an in-use swapfile, |
1266 | * which will scribble on the fs. | |
1267 | * | |
1268 | * The amount of disk space which a single swap extent represents varies. | |
1269 | * Typically it is in the 1-4 megabyte range. So we can have hundreds of | |
1270 | * extents in the list. To avoid much list walking, we cache the previous | |
1271 | * search location in `curr_swap_extent', and start new searches from there. | |
1272 | * This is extremely effective. The average number of iterations in | |
1273 | * map_swap_page() has been measured at about 0.3 per page. - akpm. | |
1274 | */ | |
53092a74 | 1275 | static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
1da177e4 LT |
1276 | { |
1277 | struct inode *inode; | |
1278 | unsigned blocks_per_page; | |
1279 | unsigned long page_no; | |
1280 | unsigned blkbits; | |
1281 | sector_t probe_block; | |
1282 | sector_t last_block; | |
53092a74 HD |
1283 | sector_t lowest_block = -1; |
1284 | sector_t highest_block = 0; | |
1285 | int nr_extents = 0; | |
1da177e4 LT |
1286 | int ret; |
1287 | ||
1288 | inode = sis->swap_file->f_mapping->host; | |
1289 | if (S_ISBLK(inode->i_mode)) { | |
1290 | ret = add_swap_extent(sis, 0, sis->max, 0); | |
53092a74 | 1291 | *span = sis->pages; |
1da177e4 LT |
1292 | goto done; |
1293 | } | |
1294 | ||
1295 | blkbits = inode->i_blkbits; | |
1296 | blocks_per_page = PAGE_SIZE >> blkbits; | |
1297 | ||
1298 | /* | |
1299 | * Map all the blocks into the extent list. This code doesn't try | |
1300 | * to be very smart. | |
1301 | */ | |
1302 | probe_block = 0; | |
1303 | page_no = 0; | |
1304 | last_block = i_size_read(inode) >> blkbits; | |
1305 | while ((probe_block + blocks_per_page) <= last_block && | |
1306 | page_no < sis->max) { | |
1307 | unsigned block_in_page; | |
1308 | sector_t first_block; | |
1309 | ||
1310 | first_block = bmap(inode, probe_block); | |
1311 | if (first_block == 0) | |
1312 | goto bad_bmap; | |
1313 | ||
1314 | /* | |
1315 | * It must be PAGE_SIZE aligned on-disk | |
1316 | */ | |
1317 | if (first_block & (blocks_per_page - 1)) { | |
1318 | probe_block++; | |
1319 | goto reprobe; | |
1320 | } | |
1321 | ||
1322 | for (block_in_page = 1; block_in_page < blocks_per_page; | |
1323 | block_in_page++) { | |
1324 | sector_t block; | |
1325 | ||
1326 | block = bmap(inode, probe_block + block_in_page); | |
1327 | if (block == 0) | |
1328 | goto bad_bmap; | |
1329 | if (block != first_block + block_in_page) { | |
1330 | /* Discontiguity */ | |
1331 | probe_block++; | |
1332 | goto reprobe; | |
1333 | } | |
1334 | } | |
1335 | ||
53092a74 HD |
1336 | first_block >>= (PAGE_SHIFT - blkbits); |
1337 | if (page_no) { /* exclude the header page */ | |
1338 | if (first_block < lowest_block) | |
1339 | lowest_block = first_block; | |
1340 | if (first_block > highest_block) | |
1341 | highest_block = first_block; | |
1342 | } | |
1343 | ||
1da177e4 LT |
1344 | /* |
1345 | * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks | |
1346 | */ | |
53092a74 HD |
1347 | ret = add_swap_extent(sis, page_no, 1, first_block); |
1348 | if (ret < 0) | |
1da177e4 | 1349 | goto out; |
53092a74 | 1350 | nr_extents += ret; |
1da177e4 LT |
1351 | page_no++; |
1352 | probe_block += blocks_per_page; | |
1353 | reprobe: | |
1354 | continue; | |
1355 | } | |
53092a74 HD |
1356 | ret = nr_extents; |
1357 | *span = 1 + highest_block - lowest_block; | |
1da177e4 | 1358 | if (page_no == 0) |
e2244ec2 | 1359 | page_no = 1; /* force Empty message */ |
1da177e4 | 1360 | sis->max = page_no; |
e2244ec2 | 1361 | sis->pages = page_no - 1; |
1da177e4 LT |
1362 | sis->highest_bit = page_no - 1; |
1363 | done: | |
1364 | sis->curr_swap_extent = list_entry(sis->extent_list.prev, | |
1365 | struct swap_extent, list); | |
1366 | goto out; | |
1367 | bad_bmap: | |
1368 | printk(KERN_ERR "swapon: swapfile has holes\n"); | |
1369 | ret = -EINVAL; | |
1370 | out: | |
1371 | return ret; | |
1372 | } | |
1373 | ||
1374 | #if 0 /* We don't need this yet */ | |
1375 | #include <linux/backing-dev.h> | |
1376 | int page_queue_congested(struct page *page) | |
1377 | { | |
1378 | struct backing_dev_info *bdi; | |
1379 | ||
51726b12 | 1380 | VM_BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */ |
1da177e4 LT |
1381 | |
1382 | if (PageSwapCache(page)) { | |
4c21e2f2 | 1383 | swp_entry_t entry = { .val = page_private(page) }; |
1da177e4 LT |
1384 | struct swap_info_struct *sis; |
1385 | ||
1386 | sis = get_swap_info_struct(swp_type(entry)); | |
1387 | bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info; | |
1388 | } else | |
1389 | bdi = page->mapping->backing_dev_info; | |
1390 | return bdi_write_congested(bdi); | |
1391 | } | |
1392 | #endif | |
1393 | ||
1394 | asmlinkage long sys_swapoff(const char __user * specialfile) | |
1395 | { | |
1396 | struct swap_info_struct * p = NULL; | |
1397 | unsigned short *swap_map; | |
1398 | struct file *swap_file, *victim; | |
1399 | struct address_space *mapping; | |
1400 | struct inode *inode; | |
1401 | char * pathname; | |
1402 | int i, type, prev; | |
1403 | int err; | |
886bb7e9 | 1404 | |
1da177e4 LT |
1405 | if (!capable(CAP_SYS_ADMIN)) |
1406 | return -EPERM; | |
1407 | ||
1408 | pathname = getname(specialfile); | |
1409 | err = PTR_ERR(pathname); | |
1410 | if (IS_ERR(pathname)) | |
1411 | goto out; | |
1412 | ||
1413 | victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0); | |
1414 | putname(pathname); | |
1415 | err = PTR_ERR(victim); | |
1416 | if (IS_ERR(victim)) | |
1417 | goto out; | |
1418 | ||
1419 | mapping = victim->f_mapping; | |
1420 | prev = -1; | |
5d337b91 | 1421 | spin_lock(&swap_lock); |
1da177e4 LT |
1422 | for (type = swap_list.head; type >= 0; type = swap_info[type].next) { |
1423 | p = swap_info + type; | |
22c6f8fd | 1424 | if (p->flags & SWP_WRITEOK) { |
1da177e4 LT |
1425 | if (p->swap_file->f_mapping == mapping) |
1426 | break; | |
1427 | } | |
1428 | prev = type; | |
1429 | } | |
1430 | if (type < 0) { | |
1431 | err = -EINVAL; | |
5d337b91 | 1432 | spin_unlock(&swap_lock); |
1da177e4 LT |
1433 | goto out_dput; |
1434 | } | |
1435 | if (!security_vm_enough_memory(p->pages)) | |
1436 | vm_unacct_memory(p->pages); | |
1437 | else { | |
1438 | err = -ENOMEM; | |
5d337b91 | 1439 | spin_unlock(&swap_lock); |
1da177e4 LT |
1440 | goto out_dput; |
1441 | } | |
1442 | if (prev < 0) { | |
1443 | swap_list.head = p->next; | |
1444 | } else { | |
1445 | swap_info[prev].next = p->next; | |
1446 | } | |
1447 | if (type == swap_list.next) { | |
1448 | /* just pick something that's safe... */ | |
1449 | swap_list.next = swap_list.head; | |
1450 | } | |
78ecba08 HD |
1451 | if (p->prio < 0) { |
1452 | for (i = p->next; i >= 0; i = swap_info[i].next) | |
1453 | swap_info[i].prio = p->prio--; | |
1454 | least_priority++; | |
1455 | } | |
1da177e4 LT |
1456 | nr_swap_pages -= p->pages; |
1457 | total_swap_pages -= p->pages; | |
1458 | p->flags &= ~SWP_WRITEOK; | |
5d337b91 | 1459 | spin_unlock(&swap_lock); |
fb4f88dc | 1460 | |
1da177e4 LT |
1461 | current->flags |= PF_SWAPOFF; |
1462 | err = try_to_unuse(type); | |
1463 | current->flags &= ~PF_SWAPOFF; | |
1464 | ||
1da177e4 LT |
1465 | if (err) { |
1466 | /* re-insert swap space back into swap_list */ | |
5d337b91 | 1467 | spin_lock(&swap_lock); |
78ecba08 HD |
1468 | if (p->prio < 0) |
1469 | p->prio = --least_priority; | |
1470 | prev = -1; | |
1471 | for (i = swap_list.head; i >= 0; i = swap_info[i].next) { | |
1da177e4 LT |
1472 | if (p->prio >= swap_info[i].prio) |
1473 | break; | |
78ecba08 HD |
1474 | prev = i; |
1475 | } | |
1da177e4 LT |
1476 | p->next = i; |
1477 | if (prev < 0) | |
1478 | swap_list.head = swap_list.next = p - swap_info; | |
1479 | else | |
1480 | swap_info[prev].next = p - swap_info; | |
1481 | nr_swap_pages += p->pages; | |
1482 | total_swap_pages += p->pages; | |
1483 | p->flags |= SWP_WRITEOK; | |
5d337b91 | 1484 | spin_unlock(&swap_lock); |
1da177e4 LT |
1485 | goto out_dput; |
1486 | } | |
52b7efdb HD |
1487 | |
1488 | /* wait for any unplug function to finish */ | |
1489 | down_write(&swap_unplug_sem); | |
1490 | up_write(&swap_unplug_sem); | |
1491 | ||
5d337b91 | 1492 | destroy_swap_extents(p); |
fc0abb14 | 1493 | mutex_lock(&swapon_mutex); |
5d337b91 HD |
1494 | spin_lock(&swap_lock); |
1495 | drain_mmlist(); | |
1496 | ||
52b7efdb | 1497 | /* wait for anyone still in scan_swap_map */ |
52b7efdb HD |
1498 | p->highest_bit = 0; /* cuts scans short */ |
1499 | while (p->flags >= SWP_SCANNING) { | |
5d337b91 | 1500 | spin_unlock(&swap_lock); |
13e4b57f | 1501 | schedule_timeout_uninterruptible(1); |
5d337b91 | 1502 | spin_lock(&swap_lock); |
52b7efdb | 1503 | } |
52b7efdb | 1504 | |
1da177e4 LT |
1505 | swap_file = p->swap_file; |
1506 | p->swap_file = NULL; | |
1507 | p->max = 0; | |
1508 | swap_map = p->swap_map; | |
1509 | p->swap_map = NULL; | |
1510 | p->flags = 0; | |
5d337b91 | 1511 | spin_unlock(&swap_lock); |
fc0abb14 | 1512 | mutex_unlock(&swapon_mutex); |
1da177e4 LT |
1513 | vfree(swap_map); |
1514 | inode = mapping->host; | |
1515 | if (S_ISBLK(inode->i_mode)) { | |
1516 | struct block_device *bdev = I_BDEV(inode); | |
1517 | set_blocksize(bdev, p->old_block_size); | |
1518 | bd_release(bdev); | |
1519 | } else { | |
1b1dcc1b | 1520 | mutex_lock(&inode->i_mutex); |
1da177e4 | 1521 | inode->i_flags &= ~S_SWAPFILE; |
1b1dcc1b | 1522 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
1523 | } |
1524 | filp_close(swap_file, NULL); | |
1525 | err = 0; | |
1526 | ||
1527 | out_dput: | |
1528 | filp_close(victim, NULL); | |
1529 | out: | |
1530 | return err; | |
1531 | } | |
1532 | ||
1533 | #ifdef CONFIG_PROC_FS | |
1534 | /* iterator */ | |
1535 | static void *swap_start(struct seq_file *swap, loff_t *pos) | |
1536 | { | |
1537 | struct swap_info_struct *ptr = swap_info; | |
1538 | int i; | |
1539 | loff_t l = *pos; | |
1540 | ||
fc0abb14 | 1541 | mutex_lock(&swapon_mutex); |
1da177e4 | 1542 | |
881e4aab SS |
1543 | if (!l) |
1544 | return SEQ_START_TOKEN; | |
1545 | ||
1da177e4 LT |
1546 | for (i = 0; i < nr_swapfiles; i++, ptr++) { |
1547 | if (!(ptr->flags & SWP_USED) || !ptr->swap_map) | |
1548 | continue; | |
881e4aab | 1549 | if (!--l) |
1da177e4 LT |
1550 | return ptr; |
1551 | } | |
1552 | ||
1553 | return NULL; | |
1554 | } | |
1555 | ||
1556 | static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) | |
1557 | { | |
881e4aab | 1558 | struct swap_info_struct *ptr; |
1da177e4 LT |
1559 | struct swap_info_struct *endptr = swap_info + nr_swapfiles; |
1560 | ||
881e4aab SS |
1561 | if (v == SEQ_START_TOKEN) |
1562 | ptr = swap_info; | |
1563 | else { | |
1564 | ptr = v; | |
1565 | ptr++; | |
1566 | } | |
1567 | ||
1568 | for (; ptr < endptr; ptr++) { | |
1da177e4 LT |
1569 | if (!(ptr->flags & SWP_USED) || !ptr->swap_map) |
1570 | continue; | |
1571 | ++*pos; | |
1572 | return ptr; | |
1573 | } | |
1574 | ||
1575 | return NULL; | |
1576 | } | |
1577 | ||
1578 | static void swap_stop(struct seq_file *swap, void *v) | |
1579 | { | |
fc0abb14 | 1580 | mutex_unlock(&swapon_mutex); |
1da177e4 LT |
1581 | } |
1582 | ||
1583 | static int swap_show(struct seq_file *swap, void *v) | |
1584 | { | |
1585 | struct swap_info_struct *ptr = v; | |
1586 | struct file *file; | |
1587 | int len; | |
1588 | ||
881e4aab SS |
1589 | if (ptr == SEQ_START_TOKEN) { |
1590 | seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n"); | |
1591 | return 0; | |
1592 | } | |
1da177e4 LT |
1593 | |
1594 | file = ptr->swap_file; | |
c32c2f63 | 1595 | len = seq_path(swap, &file->f_path, " \t\n\\"); |
6eb396dc | 1596 | seq_printf(swap, "%*s%s\t%u\t%u\t%d\n", |
886bb7e9 HD |
1597 | len < 40 ? 40 - len : 1, " ", |
1598 | S_ISBLK(file->f_path.dentry->d_inode->i_mode) ? | |
1da177e4 | 1599 | "partition" : "file\t", |
886bb7e9 HD |
1600 | ptr->pages << (PAGE_SHIFT - 10), |
1601 | ptr->inuse_pages << (PAGE_SHIFT - 10), | |
1602 | ptr->prio); | |
1da177e4 LT |
1603 | return 0; |
1604 | } | |
1605 | ||
15ad7cdc | 1606 | static const struct seq_operations swaps_op = { |
1da177e4 LT |
1607 | .start = swap_start, |
1608 | .next = swap_next, | |
1609 | .stop = swap_stop, | |
1610 | .show = swap_show | |
1611 | }; | |
1612 | ||
1613 | static int swaps_open(struct inode *inode, struct file *file) | |
1614 | { | |
1615 | return seq_open(file, &swaps_op); | |
1616 | } | |
1617 | ||
15ad7cdc | 1618 | static const struct file_operations proc_swaps_operations = { |
1da177e4 LT |
1619 | .open = swaps_open, |
1620 | .read = seq_read, | |
1621 | .llseek = seq_lseek, | |
1622 | .release = seq_release, | |
1623 | }; | |
1624 | ||
1625 | static int __init procswaps_init(void) | |
1626 | { | |
3d71f86f | 1627 | proc_create("swaps", 0, NULL, &proc_swaps_operations); |
1da177e4 LT |
1628 | return 0; |
1629 | } | |
1630 | __initcall(procswaps_init); | |
1631 | #endif /* CONFIG_PROC_FS */ | |
1632 | ||
1796316a JB |
1633 | #ifdef MAX_SWAPFILES_CHECK |
1634 | static int __init max_swapfiles_check(void) | |
1635 | { | |
1636 | MAX_SWAPFILES_CHECK(); | |
1637 | return 0; | |
1638 | } | |
1639 | late_initcall(max_swapfiles_check); | |
1640 | #endif | |
1641 | ||
1da177e4 LT |
1642 | /* |
1643 | * Written 01/25/92 by Simmule Turner, heavily changed by Linus. | |
1644 | * | |
1645 | * The swapon system call | |
1646 | */ | |
1647 | asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags) | |
1648 | { | |
1649 | struct swap_info_struct * p; | |
1650 | char *name = NULL; | |
1651 | struct block_device *bdev = NULL; | |
1652 | struct file *swap_file = NULL; | |
1653 | struct address_space *mapping; | |
1654 | unsigned int type; | |
1655 | int i, prev; | |
1656 | int error; | |
1da177e4 | 1657 | union swap_header *swap_header = NULL; |
6eb396dc HD |
1658 | unsigned int nr_good_pages = 0; |
1659 | int nr_extents = 0; | |
53092a74 | 1660 | sector_t span; |
1da177e4 | 1661 | unsigned long maxpages = 1; |
73fd8748 | 1662 | unsigned long swapfilepages; |
78ecba08 | 1663 | unsigned short *swap_map = NULL; |
1da177e4 LT |
1664 | struct page *page = NULL; |
1665 | struct inode *inode = NULL; | |
1666 | int did_down = 0; | |
1667 | ||
1668 | if (!capable(CAP_SYS_ADMIN)) | |
1669 | return -EPERM; | |
5d337b91 | 1670 | spin_lock(&swap_lock); |
1da177e4 LT |
1671 | p = swap_info; |
1672 | for (type = 0 ; type < nr_swapfiles ; type++,p++) | |
1673 | if (!(p->flags & SWP_USED)) | |
1674 | break; | |
1675 | error = -EPERM; | |
0697212a | 1676 | if (type >= MAX_SWAPFILES) { |
5d337b91 | 1677 | spin_unlock(&swap_lock); |
1da177e4 LT |
1678 | goto out; |
1679 | } | |
1680 | if (type >= nr_swapfiles) | |
1681 | nr_swapfiles = type+1; | |
78ecba08 | 1682 | memset(p, 0, sizeof(*p)); |
1da177e4 LT |
1683 | INIT_LIST_HEAD(&p->extent_list); |
1684 | p->flags = SWP_USED; | |
1da177e4 | 1685 | p->next = -1; |
5d337b91 | 1686 | spin_unlock(&swap_lock); |
1da177e4 LT |
1687 | name = getname(specialfile); |
1688 | error = PTR_ERR(name); | |
1689 | if (IS_ERR(name)) { | |
1690 | name = NULL; | |
1691 | goto bad_swap_2; | |
1692 | } | |
1693 | swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0); | |
1694 | error = PTR_ERR(swap_file); | |
1695 | if (IS_ERR(swap_file)) { | |
1696 | swap_file = NULL; | |
1697 | goto bad_swap_2; | |
1698 | } | |
1699 | ||
1700 | p->swap_file = swap_file; | |
1701 | mapping = swap_file->f_mapping; | |
1702 | inode = mapping->host; | |
1703 | ||
1704 | error = -EBUSY; | |
1705 | for (i = 0; i < nr_swapfiles; i++) { | |
1706 | struct swap_info_struct *q = &swap_info[i]; | |
1707 | ||
1708 | if (i == type || !q->swap_file) | |
1709 | continue; | |
1710 | if (mapping == q->swap_file->f_mapping) | |
1711 | goto bad_swap; | |
1712 | } | |
1713 | ||
1714 | error = -EINVAL; | |
1715 | if (S_ISBLK(inode->i_mode)) { | |
1716 | bdev = I_BDEV(inode); | |
1717 | error = bd_claim(bdev, sys_swapon); | |
1718 | if (error < 0) { | |
1719 | bdev = NULL; | |
f7b3a435 | 1720 | error = -EINVAL; |
1da177e4 LT |
1721 | goto bad_swap; |
1722 | } | |
1723 | p->old_block_size = block_size(bdev); | |
1724 | error = set_blocksize(bdev, PAGE_SIZE); | |
1725 | if (error < 0) | |
1726 | goto bad_swap; | |
1727 | p->bdev = bdev; | |
1728 | } else if (S_ISREG(inode->i_mode)) { | |
1729 | p->bdev = inode->i_sb->s_bdev; | |
1b1dcc1b | 1730 | mutex_lock(&inode->i_mutex); |
1da177e4 LT |
1731 | did_down = 1; |
1732 | if (IS_SWAPFILE(inode)) { | |
1733 | error = -EBUSY; | |
1734 | goto bad_swap; | |
1735 | } | |
1736 | } else { | |
1737 | goto bad_swap; | |
1738 | } | |
1739 | ||
73fd8748 | 1740 | swapfilepages = i_size_read(inode) >> PAGE_SHIFT; |
1da177e4 LT |
1741 | |
1742 | /* | |
1743 | * Read the swap header. | |
1744 | */ | |
1745 | if (!mapping->a_ops->readpage) { | |
1746 | error = -EINVAL; | |
1747 | goto bad_swap; | |
1748 | } | |
090d2b18 | 1749 | page = read_mapping_page(mapping, 0, swap_file); |
1da177e4 LT |
1750 | if (IS_ERR(page)) { |
1751 | error = PTR_ERR(page); | |
1752 | goto bad_swap; | |
1753 | } | |
81e33971 | 1754 | swap_header = kmap(page); |
1da177e4 | 1755 | |
81e33971 | 1756 | if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) { |
e97a3111 | 1757 | printk(KERN_ERR "Unable to find swap-space signature\n"); |
1da177e4 LT |
1758 | error = -EINVAL; |
1759 | goto bad_swap; | |
1760 | } | |
886bb7e9 | 1761 | |
81e33971 HD |
1762 | /* swap partition endianess hack... */ |
1763 | if (swab32(swap_header->info.version) == 1) { | |
1764 | swab32s(&swap_header->info.version); | |
1765 | swab32s(&swap_header->info.last_page); | |
1766 | swab32s(&swap_header->info.nr_badpages); | |
1767 | for (i = 0; i < swap_header->info.nr_badpages; i++) | |
1768 | swab32s(&swap_header->info.badpages[i]); | |
1769 | } | |
1770 | /* Check the swap header's sub-version */ | |
1771 | if (swap_header->info.version != 1) { | |
1772 | printk(KERN_WARNING | |
1773 | "Unable to handle swap header version %d\n", | |
1774 | swap_header->info.version); | |
1da177e4 LT |
1775 | error = -EINVAL; |
1776 | goto bad_swap; | |
81e33971 | 1777 | } |
1da177e4 | 1778 | |
81e33971 HD |
1779 | p->lowest_bit = 1; |
1780 | p->cluster_next = 1; | |
52b7efdb | 1781 | |
81e33971 HD |
1782 | /* |
1783 | * Find out how many pages are allowed for a single swap | |
1784 | * device. There are two limiting factors: 1) the number of | |
1785 | * bits for the swap offset in the swp_entry_t type and | |
1786 | * 2) the number of bits in the a swap pte as defined by | |
1787 | * the different architectures. In order to find the | |
1788 | * largest possible bit mask a swap entry with swap type 0 | |
1789 | * and swap offset ~0UL is created, encoded to a swap pte, | |
1790 | * decoded to a swp_entry_t again and finally the swap | |
1791 | * offset is extracted. This will mask all the bits from | |
1792 | * the initial ~0UL mask that can't be encoded in either | |
1793 | * the swp_entry_t or the architecture definition of a | |
1794 | * swap pte. | |
1795 | */ | |
1796 | maxpages = swp_offset(pte_to_swp_entry( | |
1797 | swp_entry_to_pte(swp_entry(0, ~0UL)))) - 1; | |
1798 | if (maxpages > swap_header->info.last_page) | |
1799 | maxpages = swap_header->info.last_page; | |
1800 | p->highest_bit = maxpages - 1; | |
1da177e4 | 1801 | |
81e33971 HD |
1802 | error = -EINVAL; |
1803 | if (!maxpages) | |
1804 | goto bad_swap; | |
1805 | if (swapfilepages && maxpages > swapfilepages) { | |
1806 | printk(KERN_WARNING | |
1807 | "Swap area shorter than signature indicates\n"); | |
1808 | goto bad_swap; | |
1809 | } | |
1810 | if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) | |
1811 | goto bad_swap; | |
1812 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) | |
1813 | goto bad_swap; | |
cd105df4 | 1814 | |
81e33971 HD |
1815 | /* OK, set up the swap map and apply the bad block list */ |
1816 | swap_map = vmalloc(maxpages * sizeof(short)); | |
1817 | if (!swap_map) { | |
1818 | error = -ENOMEM; | |
1819 | goto bad_swap; | |
1820 | } | |
1da177e4 | 1821 | |
81e33971 HD |
1822 | memset(swap_map, 0, maxpages * sizeof(short)); |
1823 | for (i = 0; i < swap_header->info.nr_badpages; i++) { | |
1824 | int page_nr = swap_header->info.badpages[i]; | |
1825 | if (page_nr <= 0 || page_nr >= swap_header->info.last_page) { | |
1826 | error = -EINVAL; | |
1da177e4 | 1827 | goto bad_swap; |
81e33971 HD |
1828 | } |
1829 | swap_map[page_nr] = SWAP_MAP_BAD; | |
1da177e4 | 1830 | } |
81e33971 HD |
1831 | nr_good_pages = swap_header->info.last_page - |
1832 | swap_header->info.nr_badpages - | |
1833 | 1 /* header page */; | |
e2244ec2 | 1834 | |
e2244ec2 | 1835 | if (nr_good_pages) { |
78ecba08 | 1836 | swap_map[0] = SWAP_MAP_BAD; |
e2244ec2 HD |
1837 | p->max = maxpages; |
1838 | p->pages = nr_good_pages; | |
53092a74 HD |
1839 | nr_extents = setup_swap_extents(p, &span); |
1840 | if (nr_extents < 0) { | |
1841 | error = nr_extents; | |
e2244ec2 | 1842 | goto bad_swap; |
53092a74 | 1843 | } |
e2244ec2 HD |
1844 | nr_good_pages = p->pages; |
1845 | } | |
1da177e4 LT |
1846 | if (!nr_good_pages) { |
1847 | printk(KERN_WARNING "Empty swap-file\n"); | |
1848 | error = -EINVAL; | |
1849 | goto bad_swap; | |
1850 | } | |
1da177e4 | 1851 | |
20137a49 HD |
1852 | if (blk_queue_nonrot(bdev_get_queue(p->bdev))) { |
1853 | p->flags |= SWP_SOLIDSTATE; | |
20137a49 HD |
1854 | p->cluster_next = 1 + (random32() % p->highest_bit); |
1855 | } | |
6a6ba831 HD |
1856 | if (discard_swap(p) == 0) |
1857 | p->flags |= SWP_DISCARDABLE; | |
1858 | ||
fc0abb14 | 1859 | mutex_lock(&swapon_mutex); |
5d337b91 | 1860 | spin_lock(&swap_lock); |
78ecba08 HD |
1861 | if (swap_flags & SWAP_FLAG_PREFER) |
1862 | p->prio = | |
1863 | (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; | |
1864 | else | |
1865 | p->prio = --least_priority; | |
1866 | p->swap_map = swap_map; | |
22c6f8fd | 1867 | p->flags |= SWP_WRITEOK; |
1da177e4 LT |
1868 | nr_swap_pages += nr_good_pages; |
1869 | total_swap_pages += nr_good_pages; | |
53092a74 | 1870 | |
6eb396dc | 1871 | printk(KERN_INFO "Adding %uk swap on %s. " |
20137a49 | 1872 | "Priority:%d extents:%d across:%lluk %s%s\n", |
53092a74 | 1873 | nr_good_pages<<(PAGE_SHIFT-10), name, p->prio, |
6a6ba831 | 1874 | nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), |
20137a49 HD |
1875 | (p->flags & SWP_SOLIDSTATE) ? "SS" : "", |
1876 | (p->flags & SWP_DISCARDABLE) ? "D" : ""); | |
1da177e4 LT |
1877 | |
1878 | /* insert swap space into swap_list: */ | |
1879 | prev = -1; | |
1880 | for (i = swap_list.head; i >= 0; i = swap_info[i].next) { | |
1881 | if (p->prio >= swap_info[i].prio) { | |
1882 | break; | |
1883 | } | |
1884 | prev = i; | |
1885 | } | |
1886 | p->next = i; | |
1887 | if (prev < 0) { | |
1888 | swap_list.head = swap_list.next = p - swap_info; | |
1889 | } else { | |
1890 | swap_info[prev].next = p - swap_info; | |
1891 | } | |
5d337b91 | 1892 | spin_unlock(&swap_lock); |
fc0abb14 | 1893 | mutex_unlock(&swapon_mutex); |
1da177e4 LT |
1894 | error = 0; |
1895 | goto out; | |
1896 | bad_swap: | |
1897 | if (bdev) { | |
1898 | set_blocksize(bdev, p->old_block_size); | |
1899 | bd_release(bdev); | |
1900 | } | |
4cd3bb10 | 1901 | destroy_swap_extents(p); |
1da177e4 | 1902 | bad_swap_2: |
5d337b91 | 1903 | spin_lock(&swap_lock); |
1da177e4 | 1904 | p->swap_file = NULL; |
1da177e4 | 1905 | p->flags = 0; |
5d337b91 | 1906 | spin_unlock(&swap_lock); |
1da177e4 LT |
1907 | vfree(swap_map); |
1908 | if (swap_file) | |
1909 | filp_close(swap_file, NULL); | |
1910 | out: | |
1911 | if (page && !IS_ERR(page)) { | |
1912 | kunmap(page); | |
1913 | page_cache_release(page); | |
1914 | } | |
1915 | if (name) | |
1916 | putname(name); | |
1917 | if (did_down) { | |
1918 | if (!error) | |
1919 | inode->i_flags |= S_SWAPFILE; | |
1b1dcc1b | 1920 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
1921 | } |
1922 | return error; | |
1923 | } | |
1924 | ||
1925 | void si_swapinfo(struct sysinfo *val) | |
1926 | { | |
1927 | unsigned int i; | |
1928 | unsigned long nr_to_be_unused = 0; | |
1929 | ||
5d337b91 | 1930 | spin_lock(&swap_lock); |
1da177e4 LT |
1931 | for (i = 0; i < nr_swapfiles; i++) { |
1932 | if (!(swap_info[i].flags & SWP_USED) || | |
1933 | (swap_info[i].flags & SWP_WRITEOK)) | |
1934 | continue; | |
1935 | nr_to_be_unused += swap_info[i].inuse_pages; | |
1936 | } | |
1937 | val->freeswap = nr_swap_pages + nr_to_be_unused; | |
1938 | val->totalswap = total_swap_pages + nr_to_be_unused; | |
5d337b91 | 1939 | spin_unlock(&swap_lock); |
1da177e4 LT |
1940 | } |
1941 | ||
1942 | /* | |
1943 | * Verify that a swap entry is valid and increment its swap map count. | |
1944 | * | |
1945 | * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as | |
1946 | * "permanent", but will be reclaimed by the next swapoff. | |
1947 | */ | |
1948 | int swap_duplicate(swp_entry_t entry) | |
1949 | { | |
1950 | struct swap_info_struct * p; | |
1951 | unsigned long offset, type; | |
1952 | int result = 0; | |
1953 | ||
0697212a CL |
1954 | if (is_migration_entry(entry)) |
1955 | return 1; | |
1956 | ||
1da177e4 LT |
1957 | type = swp_type(entry); |
1958 | if (type >= nr_swapfiles) | |
1959 | goto bad_file; | |
1960 | p = type + swap_info; | |
1961 | offset = swp_offset(entry); | |
1962 | ||
5d337b91 | 1963 | spin_lock(&swap_lock); |
1da177e4 LT |
1964 | if (offset < p->max && p->swap_map[offset]) { |
1965 | if (p->swap_map[offset] < SWAP_MAP_MAX - 1) { | |
1966 | p->swap_map[offset]++; | |
1967 | result = 1; | |
1968 | } else if (p->swap_map[offset] <= SWAP_MAP_MAX) { | |
1969 | if (swap_overflow++ < 5) | |
1970 | printk(KERN_WARNING "swap_dup: swap entry overflow\n"); | |
1971 | p->swap_map[offset] = SWAP_MAP_MAX; | |
1972 | result = 1; | |
1973 | } | |
1974 | } | |
5d337b91 | 1975 | spin_unlock(&swap_lock); |
1da177e4 LT |
1976 | out: |
1977 | return result; | |
1978 | ||
1979 | bad_file: | |
1980 | printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val); | |
1981 | goto out; | |
1982 | } | |
1983 | ||
1984 | struct swap_info_struct * | |
1985 | get_swap_info_struct(unsigned type) | |
1986 | { | |
1987 | return &swap_info[type]; | |
1988 | } | |
1989 | ||
1990 | /* | |
5d337b91 | 1991 | * swap_lock prevents swap_map being freed. Don't grab an extra |
1da177e4 LT |
1992 | * reference on the swaphandle, it doesn't matter if it becomes unused. |
1993 | */ | |
1994 | int valid_swaphandles(swp_entry_t entry, unsigned long *offset) | |
1995 | { | |
8952898b | 1996 | struct swap_info_struct *si; |
3f9e7949 | 1997 | int our_page_cluster = page_cluster; |
8952898b HD |
1998 | pgoff_t target, toff; |
1999 | pgoff_t base, end; | |
2000 | int nr_pages = 0; | |
1da177e4 | 2001 | |
3f9e7949 | 2002 | if (!our_page_cluster) /* no readahead */ |
1da177e4 | 2003 | return 0; |
8952898b HD |
2004 | |
2005 | si = &swap_info[swp_type(entry)]; | |
2006 | target = swp_offset(entry); | |
2007 | base = (target >> our_page_cluster) << our_page_cluster; | |
2008 | end = base + (1 << our_page_cluster); | |
2009 | if (!base) /* first page is swap header */ | |
2010 | base++; | |
1da177e4 | 2011 | |
5d337b91 | 2012 | spin_lock(&swap_lock); |
8952898b HD |
2013 | if (end > si->max) /* don't go beyond end of map */ |
2014 | end = si->max; | |
2015 | ||
2016 | /* Count contiguous allocated slots above our target */ | |
2017 | for (toff = target; ++toff < end; nr_pages++) { | |
2018 | /* Don't read in free or bad pages */ | |
2019 | if (!si->swap_map[toff]) | |
2020 | break; | |
2021 | if (si->swap_map[toff] == SWAP_MAP_BAD) | |
1da177e4 | 2022 | break; |
8952898b HD |
2023 | } |
2024 | /* Count contiguous allocated slots below our target */ | |
2025 | for (toff = target; --toff >= base; nr_pages++) { | |
1da177e4 | 2026 | /* Don't read in free or bad pages */ |
8952898b | 2027 | if (!si->swap_map[toff]) |
1da177e4 | 2028 | break; |
8952898b | 2029 | if (si->swap_map[toff] == SWAP_MAP_BAD) |
1da177e4 | 2030 | break; |
8952898b | 2031 | } |
5d337b91 | 2032 | spin_unlock(&swap_lock); |
8952898b HD |
2033 | |
2034 | /* | |
2035 | * Indicate starting offset, and return number of pages to get: | |
2036 | * if only 1, say 0, since there's then no readahead to be done. | |
2037 | */ | |
2038 | *offset = ++toff; | |
2039 | return nr_pages? ++nr_pages: 0; | |
1da177e4 | 2040 | } |