Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/mm/swapfile.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * Swap reorganised 29.12.95, Stephen Tweedie | |
6 | */ | |
7 | ||
1da177e4 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> | |
27a7faa0 | 36 | #include <linux/page_cgroup.h> |
1da177e4 | 37 | |
7c363b8c AB |
38 | static DEFINE_SPINLOCK(swap_lock); |
39 | static unsigned int nr_swapfiles; | |
b962716b | 40 | long nr_swap_pages; |
1da177e4 LT |
41 | long total_swap_pages; |
42 | static int swap_overflow; | |
78ecba08 | 43 | static int least_priority; |
1da177e4 | 44 | |
1da177e4 LT |
45 | static const char Bad_file[] = "Bad swap file entry "; |
46 | static const char Unused_file[] = "Unused swap file entry "; | |
47 | static const char Bad_offset[] = "Bad swap offset entry "; | |
48 | static const char Unused_offset[] = "Unused swap offset entry "; | |
49 | ||
7c363b8c | 50 | static struct swap_list_t swap_list = {-1, -1}; |
1da177e4 | 51 | |
f577eb30 | 52 | static struct swap_info_struct swap_info[MAX_SWAPFILES]; |
1da177e4 | 53 | |
fc0abb14 | 54 | static DEFINE_MUTEX(swapon_mutex); |
1da177e4 LT |
55 | |
56 | /* | |
57 | * We need this because the bdev->unplug_fn can sleep and we cannot | |
5d337b91 | 58 | * hold swap_lock while calling the unplug_fn. And swap_lock |
fc0abb14 | 59 | * cannot be turned into a mutex. |
1da177e4 LT |
60 | */ |
61 | static DECLARE_RWSEM(swap_unplug_sem); | |
62 | ||
1da177e4 LT |
63 | void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page) |
64 | { | |
65 | swp_entry_t entry; | |
66 | ||
67 | down_read(&swap_unplug_sem); | |
4c21e2f2 | 68 | entry.val = page_private(page); |
1da177e4 LT |
69 | if (PageSwapCache(page)) { |
70 | struct block_device *bdev = swap_info[swp_type(entry)].bdev; | |
71 | struct backing_dev_info *bdi; | |
72 | ||
73 | /* | |
74 | * If the page is removed from swapcache from under us (with a | |
75 | * racy try_to_unuse/swapoff) we need an additional reference | |
4c21e2f2 HD |
76 | * count to avoid reading garbage from page_private(page) above. |
77 | * If the WARN_ON triggers during a swapoff it maybe the race | |
1da177e4 LT |
78 | * condition and it's harmless. However if it triggers without |
79 | * swapoff it signals a problem. | |
80 | */ | |
81 | WARN_ON(page_count(page) <= 1); | |
82 | ||
83 | bdi = bdev->bd_inode->i_mapping->backing_dev_info; | |
ba32311e | 84 | blk_run_backing_dev(bdi, page); |
1da177e4 LT |
85 | } |
86 | up_read(&swap_unplug_sem); | |
87 | } | |
88 | ||
6a6ba831 HD |
89 | /* |
90 | * swapon tell device that all the old swap contents can be discarded, | |
91 | * to allow the swap device to optimize its wear-levelling. | |
92 | */ | |
93 | static int discard_swap(struct swap_info_struct *si) | |
94 | { | |
95 | struct swap_extent *se; | |
96 | int err = 0; | |
97 | ||
98 | list_for_each_entry(se, &si->extent_list, list) { | |
99 | sector_t start_block = se->start_block << (PAGE_SHIFT - 9); | |
858a2990 | 100 | sector_t nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); |
6a6ba831 HD |
101 | |
102 | if (se->start_page == 0) { | |
103 | /* Do not discard the swap header page! */ | |
104 | start_block += 1 << (PAGE_SHIFT - 9); | |
105 | nr_blocks -= 1 << (PAGE_SHIFT - 9); | |
106 | if (!nr_blocks) | |
107 | continue; | |
108 | } | |
109 | ||
110 | err = blkdev_issue_discard(si->bdev, start_block, | |
111 | nr_blocks, GFP_KERNEL); | |
112 | if (err) | |
113 | break; | |
114 | ||
115 | cond_resched(); | |
116 | } | |
117 | return err; /* That will often be -EOPNOTSUPP */ | |
118 | } | |
119 | ||
7992fde7 HD |
120 | /* |
121 | * swap allocation tell device that a cluster of swap can now be discarded, | |
122 | * to allow the swap device to optimize its wear-levelling. | |
123 | */ | |
124 | static void discard_swap_cluster(struct swap_info_struct *si, | |
125 | pgoff_t start_page, pgoff_t nr_pages) | |
126 | { | |
127 | struct swap_extent *se = si->curr_swap_extent; | |
128 | int found_extent = 0; | |
129 | ||
130 | while (nr_pages) { | |
131 | struct list_head *lh; | |
132 | ||
133 | if (se->start_page <= start_page && | |
134 | start_page < se->start_page + se->nr_pages) { | |
135 | pgoff_t offset = start_page - se->start_page; | |
136 | sector_t start_block = se->start_block + offset; | |
858a2990 | 137 | sector_t nr_blocks = se->nr_pages - offset; |
7992fde7 HD |
138 | |
139 | if (nr_blocks > nr_pages) | |
140 | nr_blocks = nr_pages; | |
141 | start_page += nr_blocks; | |
142 | nr_pages -= nr_blocks; | |
143 | ||
144 | if (!found_extent++) | |
145 | si->curr_swap_extent = se; | |
146 | ||
147 | start_block <<= PAGE_SHIFT - 9; | |
148 | nr_blocks <<= PAGE_SHIFT - 9; | |
149 | if (blkdev_issue_discard(si->bdev, start_block, | |
150 | nr_blocks, GFP_NOIO)) | |
151 | break; | |
152 | } | |
153 | ||
154 | lh = se->list.next; | |
155 | if (lh == &si->extent_list) | |
156 | lh = lh->next; | |
157 | se = list_entry(lh, struct swap_extent, list); | |
158 | } | |
159 | } | |
160 | ||
161 | static int wait_for_discard(void *word) | |
162 | { | |
163 | schedule(); | |
164 | return 0; | |
165 | } | |
166 | ||
048c27fd HD |
167 | #define SWAPFILE_CLUSTER 256 |
168 | #define LATENCY_LIMIT 256 | |
169 | ||
6eb396dc | 170 | static inline unsigned long scan_swap_map(struct swap_info_struct *si) |
1da177e4 | 171 | { |
ebebbbe9 | 172 | unsigned long offset; |
c60aa176 | 173 | unsigned long scan_base; |
7992fde7 | 174 | unsigned long last_in_cluster = 0; |
048c27fd | 175 | int latency_ration = LATENCY_LIMIT; |
7992fde7 | 176 | int found_free_cluster = 0; |
7dfad418 | 177 | |
886bb7e9 | 178 | /* |
7dfad418 HD |
179 | * We try to cluster swap pages by allocating them sequentially |
180 | * in swap. Once we've allocated SWAPFILE_CLUSTER pages this | |
181 | * way, however, we resort to first-free allocation, starting | |
182 | * a new cluster. This prevents us from scattering swap pages | |
183 | * all over the entire swap partition, so that we reduce | |
184 | * overall disk seek times between swap pages. -- sct | |
185 | * But we do now try to find an empty cluster. -Andrea | |
c60aa176 | 186 | * And we let swap pages go all over an SSD partition. Hugh |
7dfad418 HD |
187 | */ |
188 | ||
52b7efdb | 189 | si->flags += SWP_SCANNING; |
c60aa176 | 190 | scan_base = offset = si->cluster_next; |
ebebbbe9 HD |
191 | |
192 | if (unlikely(!si->cluster_nr--)) { | |
193 | if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { | |
194 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
195 | goto checks; | |
196 | } | |
7992fde7 HD |
197 | if (si->flags & SWP_DISCARDABLE) { |
198 | /* | |
199 | * Start range check on racing allocations, in case | |
200 | * they overlap the cluster we eventually decide on | |
201 | * (we scan without swap_lock to allow preemption). | |
202 | * It's hardly conceivable that cluster_nr could be | |
203 | * wrapped during our scan, but don't depend on it. | |
204 | */ | |
205 | if (si->lowest_alloc) | |
206 | goto checks; | |
207 | si->lowest_alloc = si->max; | |
208 | si->highest_alloc = 0; | |
209 | } | |
5d337b91 | 210 | spin_unlock(&swap_lock); |
7dfad418 | 211 | |
c60aa176 HD |
212 | /* |
213 | * If seek is expensive, start searching for new cluster from | |
214 | * start of partition, to minimize the span of allocated swap. | |
215 | * But if seek is cheap, search from our current position, so | |
216 | * that swap is allocated from all over the partition: if the | |
217 | * Flash Translation Layer only remaps within limited zones, | |
218 | * we don't want to wear out the first zone too quickly. | |
219 | */ | |
220 | if (!(si->flags & SWP_SOLIDSTATE)) | |
221 | scan_base = offset = si->lowest_bit; | |
7dfad418 HD |
222 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
223 | ||
224 | /* Locate the first empty (unaligned) cluster */ | |
225 | for (; last_in_cluster <= si->highest_bit; offset++) { | |
1da177e4 | 226 | if (si->swap_map[offset]) |
7dfad418 HD |
227 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
228 | else if (offset == last_in_cluster) { | |
5d337b91 | 229 | spin_lock(&swap_lock); |
ebebbbe9 HD |
230 | offset -= SWAPFILE_CLUSTER - 1; |
231 | si->cluster_next = offset; | |
232 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
7992fde7 | 233 | found_free_cluster = 1; |
ebebbbe9 | 234 | goto checks; |
1da177e4 | 235 | } |
048c27fd HD |
236 | if (unlikely(--latency_ration < 0)) { |
237 | cond_resched(); | |
238 | latency_ration = LATENCY_LIMIT; | |
239 | } | |
7dfad418 | 240 | } |
ebebbbe9 HD |
241 | |
242 | offset = si->lowest_bit; | |
c60aa176 HD |
243 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
244 | ||
245 | /* Locate the first empty (unaligned) cluster */ | |
246 | for (; last_in_cluster < scan_base; offset++) { | |
247 | if (si->swap_map[offset]) | |
248 | last_in_cluster = offset + SWAPFILE_CLUSTER; | |
249 | else if (offset == last_in_cluster) { | |
250 | spin_lock(&swap_lock); | |
251 | offset -= SWAPFILE_CLUSTER - 1; | |
252 | si->cluster_next = offset; | |
253 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
254 | found_free_cluster = 1; | |
255 | goto checks; | |
256 | } | |
257 | if (unlikely(--latency_ration < 0)) { | |
258 | cond_resched(); | |
259 | latency_ration = LATENCY_LIMIT; | |
260 | } | |
261 | } | |
262 | ||
263 | offset = scan_base; | |
5d337b91 | 264 | spin_lock(&swap_lock); |
ebebbbe9 | 265 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
7992fde7 | 266 | si->lowest_alloc = 0; |
1da177e4 | 267 | } |
7dfad418 | 268 | |
ebebbbe9 HD |
269 | checks: |
270 | if (!(si->flags & SWP_WRITEOK)) | |
52b7efdb | 271 | goto no_page; |
7dfad418 HD |
272 | if (!si->highest_bit) |
273 | goto no_page; | |
ebebbbe9 | 274 | if (offset > si->highest_bit) |
c60aa176 | 275 | scan_base = offset = si->lowest_bit; |
ebebbbe9 HD |
276 | if (si->swap_map[offset]) |
277 | goto scan; | |
278 | ||
279 | if (offset == si->lowest_bit) | |
280 | si->lowest_bit++; | |
281 | if (offset == si->highest_bit) | |
282 | si->highest_bit--; | |
283 | si->inuse_pages++; | |
284 | if (si->inuse_pages == si->pages) { | |
285 | si->lowest_bit = si->max; | |
286 | si->highest_bit = 0; | |
1da177e4 | 287 | } |
ebebbbe9 HD |
288 | si->swap_map[offset] = 1; |
289 | si->cluster_next = offset + 1; | |
290 | si->flags -= SWP_SCANNING; | |
7992fde7 HD |
291 | |
292 | if (si->lowest_alloc) { | |
293 | /* | |
294 | * Only set when SWP_DISCARDABLE, and there's a scan | |
295 | * for a free cluster in progress or just completed. | |
296 | */ | |
297 | if (found_free_cluster) { | |
298 | /* | |
299 | * To optimize wear-levelling, discard the | |
300 | * old data of the cluster, taking care not to | |
301 | * discard any of its pages that have already | |
302 | * been allocated by racing tasks (offset has | |
303 | * already stepped over any at the beginning). | |
304 | */ | |
305 | if (offset < si->highest_alloc && | |
306 | si->lowest_alloc <= last_in_cluster) | |
307 | last_in_cluster = si->lowest_alloc - 1; | |
308 | si->flags |= SWP_DISCARDING; | |
309 | spin_unlock(&swap_lock); | |
310 | ||
311 | if (offset < last_in_cluster) | |
312 | discard_swap_cluster(si, offset, | |
313 | last_in_cluster - offset + 1); | |
314 | ||
315 | spin_lock(&swap_lock); | |
316 | si->lowest_alloc = 0; | |
317 | si->flags &= ~SWP_DISCARDING; | |
318 | ||
319 | smp_mb(); /* wake_up_bit advises this */ | |
320 | wake_up_bit(&si->flags, ilog2(SWP_DISCARDING)); | |
321 | ||
322 | } else if (si->flags & SWP_DISCARDING) { | |
323 | /* | |
324 | * Delay using pages allocated by racing tasks | |
325 | * until the whole discard has been issued. We | |
326 | * could defer that delay until swap_writepage, | |
327 | * but it's easier to keep this self-contained. | |
328 | */ | |
329 | spin_unlock(&swap_lock); | |
330 | wait_on_bit(&si->flags, ilog2(SWP_DISCARDING), | |
331 | wait_for_discard, TASK_UNINTERRUPTIBLE); | |
332 | spin_lock(&swap_lock); | |
333 | } else { | |
334 | /* | |
335 | * Note pages allocated by racing tasks while | |
336 | * scan for a free cluster is in progress, so | |
337 | * that its final discard can exclude them. | |
338 | */ | |
339 | if (offset < si->lowest_alloc) | |
340 | si->lowest_alloc = offset; | |
341 | if (offset > si->highest_alloc) | |
342 | si->highest_alloc = offset; | |
343 | } | |
344 | } | |
ebebbbe9 | 345 | return offset; |
7dfad418 | 346 | |
ebebbbe9 | 347 | scan: |
5d337b91 | 348 | spin_unlock(&swap_lock); |
7dfad418 | 349 | while (++offset <= si->highest_bit) { |
52b7efdb | 350 | if (!si->swap_map[offset]) { |
5d337b91 | 351 | spin_lock(&swap_lock); |
52b7efdb HD |
352 | goto checks; |
353 | } | |
048c27fd HD |
354 | if (unlikely(--latency_ration < 0)) { |
355 | cond_resched(); | |
356 | latency_ration = LATENCY_LIMIT; | |
357 | } | |
7dfad418 | 358 | } |
c60aa176 HD |
359 | offset = si->lowest_bit; |
360 | while (++offset < scan_base) { | |
361 | if (!si->swap_map[offset]) { | |
362 | spin_lock(&swap_lock); | |
363 | goto checks; | |
364 | } | |
365 | if (unlikely(--latency_ration < 0)) { | |
366 | cond_resched(); | |
367 | latency_ration = LATENCY_LIMIT; | |
368 | } | |
369 | } | |
5d337b91 | 370 | spin_lock(&swap_lock); |
7dfad418 HD |
371 | |
372 | no_page: | |
52b7efdb | 373 | si->flags -= SWP_SCANNING; |
1da177e4 LT |
374 | return 0; |
375 | } | |
376 | ||
377 | swp_entry_t get_swap_page(void) | |
378 | { | |
fb4f88dc HD |
379 | struct swap_info_struct *si; |
380 | pgoff_t offset; | |
381 | int type, next; | |
382 | int wrapped = 0; | |
1da177e4 | 383 | |
5d337b91 | 384 | spin_lock(&swap_lock); |
1da177e4 | 385 | if (nr_swap_pages <= 0) |
fb4f88dc HD |
386 | goto noswap; |
387 | nr_swap_pages--; | |
388 | ||
389 | for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) { | |
390 | si = swap_info + type; | |
391 | next = si->next; | |
392 | if (next < 0 || | |
393 | (!wrapped && si->prio != swap_info[next].prio)) { | |
394 | next = swap_list.head; | |
395 | wrapped++; | |
1da177e4 | 396 | } |
fb4f88dc HD |
397 | |
398 | if (!si->highest_bit) | |
399 | continue; | |
400 | if (!(si->flags & SWP_WRITEOK)) | |
401 | continue; | |
402 | ||
403 | swap_list.next = next; | |
fb4f88dc | 404 | offset = scan_swap_map(si); |
5d337b91 HD |
405 | if (offset) { |
406 | spin_unlock(&swap_lock); | |
fb4f88dc | 407 | return swp_entry(type, offset); |
5d337b91 | 408 | } |
fb4f88dc | 409 | next = swap_list.next; |
1da177e4 | 410 | } |
fb4f88dc HD |
411 | |
412 | nr_swap_pages++; | |
413 | noswap: | |
5d337b91 | 414 | spin_unlock(&swap_lock); |
fb4f88dc | 415 | return (swp_entry_t) {0}; |
1da177e4 LT |
416 | } |
417 | ||
3a291a20 RW |
418 | swp_entry_t get_swap_page_of_type(int type) |
419 | { | |
420 | struct swap_info_struct *si; | |
421 | pgoff_t offset; | |
422 | ||
423 | spin_lock(&swap_lock); | |
424 | si = swap_info + type; | |
425 | if (si->flags & SWP_WRITEOK) { | |
426 | nr_swap_pages--; | |
427 | offset = scan_swap_map(si); | |
428 | if (offset) { | |
429 | spin_unlock(&swap_lock); | |
430 | return swp_entry(type, offset); | |
431 | } | |
432 | nr_swap_pages++; | |
433 | } | |
434 | spin_unlock(&swap_lock); | |
435 | return (swp_entry_t) {0}; | |
436 | } | |
437 | ||
1da177e4 LT |
438 | static struct swap_info_struct * swap_info_get(swp_entry_t entry) |
439 | { | |
440 | struct swap_info_struct * p; | |
441 | unsigned long offset, type; | |
442 | ||
443 | if (!entry.val) | |
444 | goto out; | |
445 | type = swp_type(entry); | |
446 | if (type >= nr_swapfiles) | |
447 | goto bad_nofile; | |
448 | p = & swap_info[type]; | |
449 | if (!(p->flags & SWP_USED)) | |
450 | goto bad_device; | |
451 | offset = swp_offset(entry); | |
452 | if (offset >= p->max) | |
453 | goto bad_offset; | |
454 | if (!p->swap_map[offset]) | |
455 | goto bad_free; | |
5d337b91 | 456 | spin_lock(&swap_lock); |
1da177e4 LT |
457 | return p; |
458 | ||
459 | bad_free: | |
460 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val); | |
461 | goto out; | |
462 | bad_offset: | |
463 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val); | |
464 | goto out; | |
465 | bad_device: | |
466 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val); | |
467 | goto out; | |
468 | bad_nofile: | |
469 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val); | |
470 | out: | |
471 | return NULL; | |
886bb7e9 | 472 | } |
1da177e4 | 473 | |
8c7c6e34 | 474 | static int swap_entry_free(struct swap_info_struct *p, swp_entry_t ent) |
1da177e4 | 475 | { |
8c7c6e34 | 476 | unsigned long offset = swp_offset(ent); |
1da177e4 LT |
477 | int count = p->swap_map[offset]; |
478 | ||
479 | if (count < SWAP_MAP_MAX) { | |
480 | count--; | |
481 | p->swap_map[offset] = count; | |
482 | if (!count) { | |
483 | if (offset < p->lowest_bit) | |
484 | p->lowest_bit = offset; | |
485 | if (offset > p->highest_bit) | |
486 | p->highest_bit = offset; | |
89d09a2c HD |
487 | if (p->prio > swap_info[swap_list.next].prio) |
488 | swap_list.next = p - swap_info; | |
1da177e4 LT |
489 | nr_swap_pages++; |
490 | p->inuse_pages--; | |
8c7c6e34 | 491 | mem_cgroup_uncharge_swap(ent); |
1da177e4 LT |
492 | } |
493 | } | |
494 | return count; | |
495 | } | |
496 | ||
497 | /* | |
498 | * Caller has made sure that the swapdevice corresponding to entry | |
499 | * is still around or has not been recycled. | |
500 | */ | |
501 | void swap_free(swp_entry_t entry) | |
502 | { | |
503 | struct swap_info_struct * p; | |
504 | ||
505 | p = swap_info_get(entry); | |
506 | if (p) { | |
8c7c6e34 | 507 | swap_entry_free(p, entry); |
5d337b91 | 508 | spin_unlock(&swap_lock); |
1da177e4 LT |
509 | } |
510 | } | |
511 | ||
512 | /* | |
c475a8ab | 513 | * How many references to page are currently swapped out? |
1da177e4 | 514 | */ |
c475a8ab | 515 | static inline int page_swapcount(struct page *page) |
1da177e4 | 516 | { |
c475a8ab HD |
517 | int count = 0; |
518 | struct swap_info_struct *p; | |
1da177e4 LT |
519 | swp_entry_t entry; |
520 | ||
4c21e2f2 | 521 | entry.val = page_private(page); |
1da177e4 LT |
522 | p = swap_info_get(entry); |
523 | if (p) { | |
c475a8ab HD |
524 | /* Subtract the 1 for the swap cache itself */ |
525 | count = p->swap_map[swp_offset(entry)] - 1; | |
5d337b91 | 526 | spin_unlock(&swap_lock); |
1da177e4 | 527 | } |
c475a8ab | 528 | return count; |
1da177e4 LT |
529 | } |
530 | ||
531 | /* | |
7b1fe597 HD |
532 | * We can write to an anon page without COW if there are no other references |
533 | * to it. And as a side-effect, free up its swap: because the old content | |
534 | * on disk will never be read, and seeking back there to write new content | |
535 | * later would only waste time away from clustering. | |
1da177e4 | 536 | */ |
7b1fe597 | 537 | int reuse_swap_page(struct page *page) |
1da177e4 | 538 | { |
c475a8ab HD |
539 | int count; |
540 | ||
51726b12 | 541 | VM_BUG_ON(!PageLocked(page)); |
c475a8ab | 542 | count = page_mapcount(page); |
7b1fe597 | 543 | if (count <= 1 && PageSwapCache(page)) { |
c475a8ab | 544 | count += page_swapcount(page); |
7b1fe597 HD |
545 | if (count == 1 && !PageWriteback(page)) { |
546 | delete_from_swap_cache(page); | |
547 | SetPageDirty(page); | |
548 | } | |
549 | } | |
c475a8ab | 550 | return count == 1; |
1da177e4 LT |
551 | } |
552 | ||
553 | /* | |
a2c43eed HD |
554 | * If swap is getting full, or if there are no more mappings of this page, |
555 | * then try_to_free_swap is called to free its swap space. | |
1da177e4 | 556 | */ |
a2c43eed | 557 | int try_to_free_swap(struct page *page) |
1da177e4 | 558 | { |
51726b12 | 559 | VM_BUG_ON(!PageLocked(page)); |
1da177e4 LT |
560 | |
561 | if (!PageSwapCache(page)) | |
562 | return 0; | |
563 | if (PageWriteback(page)) | |
564 | return 0; | |
a2c43eed | 565 | if (page_swapcount(page)) |
1da177e4 LT |
566 | return 0; |
567 | ||
a2c43eed HD |
568 | delete_from_swap_cache(page); |
569 | SetPageDirty(page); | |
570 | return 1; | |
68a22394 RR |
571 | } |
572 | ||
1da177e4 LT |
573 | /* |
574 | * Free the swap entry like above, but also try to | |
575 | * free the page cache entry if it is the last user. | |
576 | */ | |
2509ef26 | 577 | int free_swap_and_cache(swp_entry_t entry) |
1da177e4 | 578 | { |
2509ef26 | 579 | struct swap_info_struct *p; |
1da177e4 LT |
580 | struct page *page = NULL; |
581 | ||
0697212a | 582 | if (is_migration_entry(entry)) |
2509ef26 | 583 | return 1; |
0697212a | 584 | |
1da177e4 LT |
585 | p = swap_info_get(entry); |
586 | if (p) { | |
8c7c6e34 | 587 | if (swap_entry_free(p, entry) == 1) { |
93fac704 | 588 | page = find_get_page(&swapper_space, entry.val); |
8413ac9d | 589 | if (page && !trylock_page(page)) { |
93fac704 NP |
590 | page_cache_release(page); |
591 | page = NULL; | |
592 | } | |
593 | } | |
5d337b91 | 594 | spin_unlock(&swap_lock); |
1da177e4 LT |
595 | } |
596 | if (page) { | |
a2c43eed HD |
597 | /* |
598 | * Not mapped elsewhere, or swap space full? Free it! | |
599 | * Also recheck PageSwapCache now page is locked (above). | |
600 | */ | |
93fac704 | 601 | if (PageSwapCache(page) && !PageWriteback(page) && |
a2c43eed | 602 | (!page_mapped(page) || vm_swap_full())) { |
1da177e4 LT |
603 | delete_from_swap_cache(page); |
604 | SetPageDirty(page); | |
605 | } | |
606 | unlock_page(page); | |
607 | page_cache_release(page); | |
608 | } | |
2509ef26 | 609 | return p != NULL; |
1da177e4 LT |
610 | } |
611 | ||
b0cb1a19 | 612 | #ifdef CONFIG_HIBERNATION |
f577eb30 | 613 | /* |
915bae9e | 614 | * Find the swap type that corresponds to given device (if any). |
f577eb30 | 615 | * |
915bae9e RW |
616 | * @offset - number of the PAGE_SIZE-sized block of the device, starting |
617 | * from 0, in which the swap header is expected to be located. | |
618 | * | |
619 | * This is needed for the suspend to disk (aka swsusp). | |
f577eb30 | 620 | */ |
7bf23687 | 621 | int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) |
f577eb30 | 622 | { |
915bae9e | 623 | struct block_device *bdev = NULL; |
f577eb30 RW |
624 | int i; |
625 | ||
915bae9e RW |
626 | if (device) |
627 | bdev = bdget(device); | |
628 | ||
f577eb30 RW |
629 | spin_lock(&swap_lock); |
630 | for (i = 0; i < nr_swapfiles; i++) { | |
915bae9e | 631 | struct swap_info_struct *sis = swap_info + i; |
f577eb30 | 632 | |
915bae9e | 633 | if (!(sis->flags & SWP_WRITEOK)) |
f577eb30 | 634 | continue; |
b6b5bce3 | 635 | |
915bae9e | 636 | if (!bdev) { |
7bf23687 RW |
637 | if (bdev_p) |
638 | *bdev_p = sis->bdev; | |
639 | ||
6e1819d6 RW |
640 | spin_unlock(&swap_lock); |
641 | return i; | |
642 | } | |
915bae9e RW |
643 | if (bdev == sis->bdev) { |
644 | struct swap_extent *se; | |
645 | ||
646 | se = list_entry(sis->extent_list.next, | |
647 | struct swap_extent, list); | |
648 | if (se->start_block == offset) { | |
7bf23687 RW |
649 | if (bdev_p) |
650 | *bdev_p = sis->bdev; | |
651 | ||
915bae9e RW |
652 | spin_unlock(&swap_lock); |
653 | bdput(bdev); | |
654 | return i; | |
655 | } | |
f577eb30 RW |
656 | } |
657 | } | |
658 | spin_unlock(&swap_lock); | |
915bae9e RW |
659 | if (bdev) |
660 | bdput(bdev); | |
661 | ||
f577eb30 RW |
662 | return -ENODEV; |
663 | } | |
664 | ||
665 | /* | |
666 | * Return either the total number of swap pages of given type, or the number | |
667 | * of free pages of that type (depending on @free) | |
668 | * | |
669 | * This is needed for software suspend | |
670 | */ | |
671 | unsigned int count_swap_pages(int type, int free) | |
672 | { | |
673 | unsigned int n = 0; | |
674 | ||
675 | if (type < nr_swapfiles) { | |
676 | spin_lock(&swap_lock); | |
677 | if (swap_info[type].flags & SWP_WRITEOK) { | |
678 | n = swap_info[type].pages; | |
679 | if (free) | |
680 | n -= swap_info[type].inuse_pages; | |
681 | } | |
682 | spin_unlock(&swap_lock); | |
683 | } | |
684 | return n; | |
685 | } | |
686 | #endif | |
687 | ||
1da177e4 | 688 | /* |
72866f6f HD |
689 | * No need to decide whether this PTE shares the swap entry with others, |
690 | * just let do_wp_page work it out if a write is requested later - to | |
691 | * force COW, vm_page_prot omits write permission from any private vma. | |
1da177e4 | 692 | */ |
044d66c1 | 693 | static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
1da177e4 LT |
694 | unsigned long addr, swp_entry_t entry, struct page *page) |
695 | { | |
7a81b88c | 696 | struct mem_cgroup *ptr = NULL; |
044d66c1 HD |
697 | spinlock_t *ptl; |
698 | pte_t *pte; | |
699 | int ret = 1; | |
700 | ||
2c26fdd7 | 701 | if (mem_cgroup_try_charge_swapin(vma->vm_mm, page, GFP_KERNEL, &ptr)) |
044d66c1 HD |
702 | ret = -ENOMEM; |
703 | ||
704 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); | |
705 | if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) { | |
706 | if (ret > 0) | |
7a81b88c | 707 | mem_cgroup_cancel_charge_swapin(ptr); |
044d66c1 HD |
708 | ret = 0; |
709 | goto out; | |
710 | } | |
8a9f3ccd | 711 | |
4294621f | 712 | inc_mm_counter(vma->vm_mm, anon_rss); |
1da177e4 LT |
713 | get_page(page); |
714 | set_pte_at(vma->vm_mm, addr, pte, | |
715 | pte_mkold(mk_pte(page, vma->vm_page_prot))); | |
716 | page_add_anon_rmap(page, vma, addr); | |
7a81b88c | 717 | mem_cgroup_commit_charge_swapin(page, ptr); |
1da177e4 LT |
718 | swap_free(entry); |
719 | /* | |
720 | * Move the page to the active list so it is not | |
721 | * immediately swapped out again after swapon. | |
722 | */ | |
723 | activate_page(page); | |
044d66c1 HD |
724 | out: |
725 | pte_unmap_unlock(pte, ptl); | |
726 | return ret; | |
1da177e4 LT |
727 | } |
728 | ||
729 | static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, | |
730 | unsigned long addr, unsigned long end, | |
731 | swp_entry_t entry, struct page *page) | |
732 | { | |
1da177e4 | 733 | pte_t swp_pte = swp_entry_to_pte(entry); |
705e87c0 | 734 | pte_t *pte; |
8a9f3ccd | 735 | int ret = 0; |
1da177e4 | 736 | |
044d66c1 HD |
737 | /* |
738 | * We don't actually need pte lock while scanning for swp_pte: since | |
739 | * we hold page lock and mmap_sem, swp_pte cannot be inserted into the | |
740 | * page table while we're scanning; though it could get zapped, and on | |
741 | * some architectures (e.g. x86_32 with PAE) we might catch a glimpse | |
742 | * of unmatched parts which look like swp_pte, so unuse_pte must | |
743 | * recheck under pte lock. Scanning without pte lock lets it be | |
744 | * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE. | |
745 | */ | |
746 | pte = pte_offset_map(pmd, addr); | |
1da177e4 LT |
747 | do { |
748 | /* | |
749 | * swapoff spends a _lot_ of time in this loop! | |
750 | * Test inline before going to call unuse_pte. | |
751 | */ | |
752 | if (unlikely(pte_same(*pte, swp_pte))) { | |
044d66c1 HD |
753 | pte_unmap(pte); |
754 | ret = unuse_pte(vma, pmd, addr, entry, page); | |
755 | if (ret) | |
756 | goto out; | |
757 | pte = pte_offset_map(pmd, addr); | |
1da177e4 LT |
758 | } |
759 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
044d66c1 HD |
760 | pte_unmap(pte - 1); |
761 | out: | |
8a9f3ccd | 762 | return ret; |
1da177e4 LT |
763 | } |
764 | ||
765 | static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, | |
766 | unsigned long addr, unsigned long end, | |
767 | swp_entry_t entry, struct page *page) | |
768 | { | |
769 | pmd_t *pmd; | |
770 | unsigned long next; | |
8a9f3ccd | 771 | int ret; |
1da177e4 LT |
772 | |
773 | pmd = pmd_offset(pud, addr); | |
774 | do { | |
775 | next = pmd_addr_end(addr, end); | |
776 | if (pmd_none_or_clear_bad(pmd)) | |
777 | continue; | |
8a9f3ccd BS |
778 | ret = unuse_pte_range(vma, pmd, addr, next, entry, page); |
779 | if (ret) | |
780 | return ret; | |
1da177e4 LT |
781 | } while (pmd++, addr = next, addr != end); |
782 | return 0; | |
783 | } | |
784 | ||
785 | static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd, | |
786 | unsigned long addr, unsigned long end, | |
787 | swp_entry_t entry, struct page *page) | |
788 | { | |
789 | pud_t *pud; | |
790 | unsigned long next; | |
8a9f3ccd | 791 | int ret; |
1da177e4 LT |
792 | |
793 | pud = pud_offset(pgd, addr); | |
794 | do { | |
795 | next = pud_addr_end(addr, end); | |
796 | if (pud_none_or_clear_bad(pud)) | |
797 | continue; | |
8a9f3ccd BS |
798 | ret = unuse_pmd_range(vma, pud, addr, next, entry, page); |
799 | if (ret) | |
800 | return ret; | |
1da177e4 LT |
801 | } while (pud++, addr = next, addr != end); |
802 | return 0; | |
803 | } | |
804 | ||
805 | static int unuse_vma(struct vm_area_struct *vma, | |
806 | swp_entry_t entry, struct page *page) | |
807 | { | |
808 | pgd_t *pgd; | |
809 | unsigned long addr, end, next; | |
8a9f3ccd | 810 | int ret; |
1da177e4 LT |
811 | |
812 | if (page->mapping) { | |
813 | addr = page_address_in_vma(page, vma); | |
814 | if (addr == -EFAULT) | |
815 | return 0; | |
816 | else | |
817 | end = addr + PAGE_SIZE; | |
818 | } else { | |
819 | addr = vma->vm_start; | |
820 | end = vma->vm_end; | |
821 | } | |
822 | ||
823 | pgd = pgd_offset(vma->vm_mm, addr); | |
824 | do { | |
825 | next = pgd_addr_end(addr, end); | |
826 | if (pgd_none_or_clear_bad(pgd)) | |
827 | continue; | |
8a9f3ccd BS |
828 | ret = unuse_pud_range(vma, pgd, addr, next, entry, page); |
829 | if (ret) | |
830 | return ret; | |
1da177e4 LT |
831 | } while (pgd++, addr = next, addr != end); |
832 | return 0; | |
833 | } | |
834 | ||
835 | static int unuse_mm(struct mm_struct *mm, | |
836 | swp_entry_t entry, struct page *page) | |
837 | { | |
838 | struct vm_area_struct *vma; | |
8a9f3ccd | 839 | int ret = 0; |
1da177e4 LT |
840 | |
841 | if (!down_read_trylock(&mm->mmap_sem)) { | |
842 | /* | |
7d03431c FLVC |
843 | * Activate page so shrink_inactive_list is unlikely to unmap |
844 | * its ptes while lock is dropped, so swapoff can make progress. | |
1da177e4 | 845 | */ |
c475a8ab | 846 | activate_page(page); |
1da177e4 LT |
847 | unlock_page(page); |
848 | down_read(&mm->mmap_sem); | |
849 | lock_page(page); | |
850 | } | |
1da177e4 | 851 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
8a9f3ccd | 852 | if (vma->anon_vma && (ret = unuse_vma(vma, entry, page))) |
1da177e4 LT |
853 | break; |
854 | } | |
1da177e4 | 855 | up_read(&mm->mmap_sem); |
8a9f3ccd | 856 | return (ret < 0)? ret: 0; |
1da177e4 LT |
857 | } |
858 | ||
859 | /* | |
860 | * Scan swap_map from current position to next entry still in use. | |
861 | * Recycle to start on reaching the end, returning 0 when empty. | |
862 | */ | |
6eb396dc HD |
863 | static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
864 | unsigned int prev) | |
1da177e4 | 865 | { |
6eb396dc HD |
866 | unsigned int max = si->max; |
867 | unsigned int i = prev; | |
1da177e4 LT |
868 | int count; |
869 | ||
870 | /* | |
5d337b91 | 871 | * No need for swap_lock here: we're just looking |
1da177e4 LT |
872 | * for whether an entry is in use, not modifying it; false |
873 | * hits are okay, and sys_swapoff() has already prevented new | |
5d337b91 | 874 | * allocations from this area (while holding swap_lock). |
1da177e4 LT |
875 | */ |
876 | for (;;) { | |
877 | if (++i >= max) { | |
878 | if (!prev) { | |
879 | i = 0; | |
880 | break; | |
881 | } | |
882 | /* | |
883 | * No entries in use at top of swap_map, | |
884 | * loop back to start and recheck there. | |
885 | */ | |
886 | max = prev + 1; | |
887 | prev = 0; | |
888 | i = 1; | |
889 | } | |
890 | count = si->swap_map[i]; | |
891 | if (count && count != SWAP_MAP_BAD) | |
892 | break; | |
893 | } | |
894 | return i; | |
895 | } | |
896 | ||
897 | /* | |
898 | * We completely avoid races by reading each swap page in advance, | |
899 | * and then search for the process using it. All the necessary | |
900 | * page table adjustments can then be made atomically. | |
901 | */ | |
902 | static int try_to_unuse(unsigned int type) | |
903 | { | |
904 | struct swap_info_struct * si = &swap_info[type]; | |
905 | struct mm_struct *start_mm; | |
906 | unsigned short *swap_map; | |
907 | unsigned short swcount; | |
908 | struct page *page; | |
909 | swp_entry_t entry; | |
6eb396dc | 910 | unsigned int i = 0; |
1da177e4 LT |
911 | int retval = 0; |
912 | int reset_overflow = 0; | |
913 | int shmem; | |
914 | ||
915 | /* | |
916 | * When searching mms for an entry, a good strategy is to | |
917 | * start at the first mm we freed the previous entry from | |
918 | * (though actually we don't notice whether we or coincidence | |
919 | * freed the entry). Initialize this start_mm with a hold. | |
920 | * | |
921 | * A simpler strategy would be to start at the last mm we | |
922 | * freed the previous entry from; but that would take less | |
923 | * advantage of mmlist ordering, which clusters forked mms | |
924 | * together, child after parent. If we race with dup_mmap(), we | |
925 | * prefer to resolve parent before child, lest we miss entries | |
926 | * duplicated after we scanned child: using last mm would invert | |
927 | * that. Though it's only a serious concern when an overflowed | |
928 | * swap count is reset from SWAP_MAP_MAX, preventing a rescan. | |
929 | */ | |
930 | start_mm = &init_mm; | |
931 | atomic_inc(&init_mm.mm_users); | |
932 | ||
933 | /* | |
934 | * Keep on scanning until all entries have gone. Usually, | |
935 | * one pass through swap_map is enough, but not necessarily: | |
936 | * there are races when an instance of an entry might be missed. | |
937 | */ | |
938 | while ((i = find_next_to_unuse(si, i)) != 0) { | |
939 | if (signal_pending(current)) { | |
940 | retval = -EINTR; | |
941 | break; | |
942 | } | |
943 | ||
886bb7e9 | 944 | /* |
1da177e4 LT |
945 | * Get a page for the entry, using the existing swap |
946 | * cache page if there is one. Otherwise, get a clean | |
886bb7e9 | 947 | * page and read the swap into it. |
1da177e4 LT |
948 | */ |
949 | swap_map = &si->swap_map[i]; | |
950 | entry = swp_entry(type, i); | |
02098fea HD |
951 | page = read_swap_cache_async(entry, |
952 | GFP_HIGHUSER_MOVABLE, NULL, 0); | |
1da177e4 LT |
953 | if (!page) { |
954 | /* | |
955 | * Either swap_duplicate() failed because entry | |
956 | * has been freed independently, and will not be | |
957 | * reused since sys_swapoff() already disabled | |
958 | * allocation from here, or alloc_page() failed. | |
959 | */ | |
960 | if (!*swap_map) | |
961 | continue; | |
962 | retval = -ENOMEM; | |
963 | break; | |
964 | } | |
965 | ||
966 | /* | |
967 | * Don't hold on to start_mm if it looks like exiting. | |
968 | */ | |
969 | if (atomic_read(&start_mm->mm_users) == 1) { | |
970 | mmput(start_mm); | |
971 | start_mm = &init_mm; | |
972 | atomic_inc(&init_mm.mm_users); | |
973 | } | |
974 | ||
975 | /* | |
976 | * Wait for and lock page. When do_swap_page races with | |
977 | * try_to_unuse, do_swap_page can handle the fault much | |
978 | * faster than try_to_unuse can locate the entry. This | |
979 | * apparently redundant "wait_on_page_locked" lets try_to_unuse | |
980 | * defer to do_swap_page in such a case - in some tests, | |
981 | * do_swap_page and try_to_unuse repeatedly compete. | |
982 | */ | |
983 | wait_on_page_locked(page); | |
984 | wait_on_page_writeback(page); | |
985 | lock_page(page); | |
986 | wait_on_page_writeback(page); | |
987 | ||
988 | /* | |
989 | * Remove all references to entry. | |
990 | * Whenever we reach init_mm, there's no address space | |
991 | * to search, but use it as a reminder to search shmem. | |
992 | */ | |
993 | shmem = 0; | |
994 | swcount = *swap_map; | |
995 | if (swcount > 1) { | |
996 | if (start_mm == &init_mm) | |
997 | shmem = shmem_unuse(entry, page); | |
998 | else | |
999 | retval = unuse_mm(start_mm, entry, page); | |
1000 | } | |
1001 | if (*swap_map > 1) { | |
1002 | int set_start_mm = (*swap_map >= swcount); | |
1003 | struct list_head *p = &start_mm->mmlist; | |
1004 | struct mm_struct *new_start_mm = start_mm; | |
1005 | struct mm_struct *prev_mm = start_mm; | |
1006 | struct mm_struct *mm; | |
1007 | ||
1008 | atomic_inc(&new_start_mm->mm_users); | |
1009 | atomic_inc(&prev_mm->mm_users); | |
1010 | spin_lock(&mmlist_lock); | |
2e0e26c7 | 1011 | while (*swap_map > 1 && !retval && !shmem && |
1da177e4 LT |
1012 | (p = p->next) != &start_mm->mmlist) { |
1013 | mm = list_entry(p, struct mm_struct, mmlist); | |
70af7c5c | 1014 | if (!atomic_inc_not_zero(&mm->mm_users)) |
1da177e4 | 1015 | continue; |
1da177e4 LT |
1016 | spin_unlock(&mmlist_lock); |
1017 | mmput(prev_mm); | |
1018 | prev_mm = mm; | |
1019 | ||
1020 | cond_resched(); | |
1021 | ||
1022 | swcount = *swap_map; | |
1023 | if (swcount <= 1) | |
1024 | ; | |
1025 | else if (mm == &init_mm) { | |
1026 | set_start_mm = 1; | |
1027 | shmem = shmem_unuse(entry, page); | |
1028 | } else | |
1029 | retval = unuse_mm(mm, entry, page); | |
1030 | if (set_start_mm && *swap_map < swcount) { | |
1031 | mmput(new_start_mm); | |
1032 | atomic_inc(&mm->mm_users); | |
1033 | new_start_mm = mm; | |
1034 | set_start_mm = 0; | |
1035 | } | |
1036 | spin_lock(&mmlist_lock); | |
1037 | } | |
1038 | spin_unlock(&mmlist_lock); | |
1039 | mmput(prev_mm); | |
1040 | mmput(start_mm); | |
1041 | start_mm = new_start_mm; | |
1042 | } | |
2e0e26c7 HD |
1043 | if (shmem) { |
1044 | /* page has already been unlocked and released */ | |
1045 | if (shmem > 0) | |
1046 | continue; | |
1047 | retval = shmem; | |
1048 | break; | |
1049 | } | |
1da177e4 LT |
1050 | if (retval) { |
1051 | unlock_page(page); | |
1052 | page_cache_release(page); | |
1053 | break; | |
1054 | } | |
1055 | ||
1056 | /* | |
1057 | * How could swap count reach 0x7fff when the maximum | |
1058 | * pid is 0x7fff, and there's no way to repeat a swap | |
1059 | * page within an mm (except in shmem, where it's the | |
1060 | * shared object which takes the reference count)? | |
1061 | * We believe SWAP_MAP_MAX cannot occur in Linux 2.4. | |
1062 | * | |
1063 | * If that's wrong, then we should worry more about | |
1064 | * exit_mmap() and do_munmap() cases described above: | |
1065 | * we might be resetting SWAP_MAP_MAX too early here. | |
1066 | * We know "Undead"s can happen, they're okay, so don't | |
1067 | * report them; but do report if we reset SWAP_MAP_MAX. | |
1068 | */ | |
1069 | if (*swap_map == SWAP_MAP_MAX) { | |
5d337b91 | 1070 | spin_lock(&swap_lock); |
1da177e4 | 1071 | *swap_map = 1; |
5d337b91 | 1072 | spin_unlock(&swap_lock); |
1da177e4 LT |
1073 | reset_overflow = 1; |
1074 | } | |
1075 | ||
1076 | /* | |
1077 | * If a reference remains (rare), we would like to leave | |
1078 | * the page in the swap cache; but try_to_unmap could | |
1079 | * then re-duplicate the entry once we drop page lock, | |
1080 | * so we might loop indefinitely; also, that page could | |
1081 | * not be swapped out to other storage meanwhile. So: | |
1082 | * delete from cache even if there's another reference, | |
1083 | * after ensuring that the data has been saved to disk - | |
1084 | * since if the reference remains (rarer), it will be | |
1085 | * read from disk into another page. Splitting into two | |
1086 | * pages would be incorrect if swap supported "shared | |
1087 | * private" pages, but they are handled by tmpfs files. | |
1da177e4 LT |
1088 | */ |
1089 | if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) { | |
1090 | struct writeback_control wbc = { | |
1091 | .sync_mode = WB_SYNC_NONE, | |
1092 | }; | |
1093 | ||
1094 | swap_writepage(page, &wbc); | |
1095 | lock_page(page); | |
1096 | wait_on_page_writeback(page); | |
1097 | } | |
68bdc8d6 HD |
1098 | |
1099 | /* | |
1100 | * It is conceivable that a racing task removed this page from | |
1101 | * swap cache just before we acquired the page lock at the top, | |
1102 | * or while we dropped it in unuse_mm(). The page might even | |
1103 | * be back in swap cache on another swap area: that we must not | |
1104 | * delete, since it may not have been written out to swap yet. | |
1105 | */ | |
1106 | if (PageSwapCache(page) && | |
1107 | likely(page_private(page) == entry.val)) | |
2e0e26c7 | 1108 | delete_from_swap_cache(page); |
1da177e4 LT |
1109 | |
1110 | /* | |
1111 | * So we could skip searching mms once swap count went | |
1112 | * to 1, we did not mark any present ptes as dirty: must | |
2706a1b8 | 1113 | * mark page dirty so shrink_page_list will preserve it. |
1da177e4 LT |
1114 | */ |
1115 | SetPageDirty(page); | |
1116 | unlock_page(page); | |
1117 | page_cache_release(page); | |
1118 | ||
1119 | /* | |
1120 | * Make sure that we aren't completely killing | |
1121 | * interactive performance. | |
1122 | */ | |
1123 | cond_resched(); | |
1124 | } | |
1125 | ||
1126 | mmput(start_mm); | |
1127 | if (reset_overflow) { | |
1128 | printk(KERN_WARNING "swapoff: cleared swap entry overflow\n"); | |
1129 | swap_overflow = 0; | |
1130 | } | |
1131 | return retval; | |
1132 | } | |
1133 | ||
1134 | /* | |
5d337b91 HD |
1135 | * After a successful try_to_unuse, if no swap is now in use, we know |
1136 | * we can empty the mmlist. swap_lock must be held on entry and exit. | |
1137 | * Note that mmlist_lock nests inside swap_lock, and an mm must be | |
1da177e4 LT |
1138 | * added to the mmlist just after page_duplicate - before would be racy. |
1139 | */ | |
1140 | static void drain_mmlist(void) | |
1141 | { | |
1142 | struct list_head *p, *next; | |
1143 | unsigned int i; | |
1144 | ||
1145 | for (i = 0; i < nr_swapfiles; i++) | |
1146 | if (swap_info[i].inuse_pages) | |
1147 | return; | |
1148 | spin_lock(&mmlist_lock); | |
1149 | list_for_each_safe(p, next, &init_mm.mmlist) | |
1150 | list_del_init(p); | |
1151 | spin_unlock(&mmlist_lock); | |
1152 | } | |
1153 | ||
1154 | /* | |
1155 | * Use this swapdev's extent info to locate the (PAGE_SIZE) block which | |
1156 | * corresponds to page offset `offset'. | |
1157 | */ | |
1158 | sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset) | |
1159 | { | |
1160 | struct swap_extent *se = sis->curr_swap_extent; | |
1161 | struct swap_extent *start_se = se; | |
1162 | ||
1163 | for ( ; ; ) { | |
1164 | struct list_head *lh; | |
1165 | ||
1166 | if (se->start_page <= offset && | |
1167 | offset < (se->start_page + se->nr_pages)) { | |
1168 | return se->start_block + (offset - se->start_page); | |
1169 | } | |
11d31886 | 1170 | lh = se->list.next; |
1da177e4 | 1171 | if (lh == &sis->extent_list) |
11d31886 | 1172 | lh = lh->next; |
1da177e4 LT |
1173 | se = list_entry(lh, struct swap_extent, list); |
1174 | sis->curr_swap_extent = se; | |
1175 | BUG_ON(se == start_se); /* It *must* be present */ | |
1176 | } | |
1177 | } | |
1178 | ||
b0cb1a19 | 1179 | #ifdef CONFIG_HIBERNATION |
3aef83e0 RW |
1180 | /* |
1181 | * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev | |
1182 | * corresponding to given index in swap_info (swap type). | |
1183 | */ | |
1184 | sector_t swapdev_block(int swap_type, pgoff_t offset) | |
1185 | { | |
1186 | struct swap_info_struct *sis; | |
1187 | ||
1188 | if (swap_type >= nr_swapfiles) | |
1189 | return 0; | |
1190 | ||
1191 | sis = swap_info + swap_type; | |
1192 | return (sis->flags & SWP_WRITEOK) ? map_swap_page(sis, offset) : 0; | |
1193 | } | |
b0cb1a19 | 1194 | #endif /* CONFIG_HIBERNATION */ |
3aef83e0 | 1195 | |
1da177e4 LT |
1196 | /* |
1197 | * Free all of a swapdev's extent information | |
1198 | */ | |
1199 | static void destroy_swap_extents(struct swap_info_struct *sis) | |
1200 | { | |
1201 | while (!list_empty(&sis->extent_list)) { | |
1202 | struct swap_extent *se; | |
1203 | ||
1204 | se = list_entry(sis->extent_list.next, | |
1205 | struct swap_extent, list); | |
1206 | list_del(&se->list); | |
1207 | kfree(se); | |
1208 | } | |
1da177e4 LT |
1209 | } |
1210 | ||
1211 | /* | |
1212 | * Add a block range (and the corresponding page range) into this swapdev's | |
11d31886 | 1213 | * extent list. The extent list is kept sorted in page order. |
1da177e4 | 1214 | * |
11d31886 | 1215 | * This function rather assumes that it is called in ascending page order. |
1da177e4 LT |
1216 | */ |
1217 | static int | |
1218 | add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, | |
1219 | unsigned long nr_pages, sector_t start_block) | |
1220 | { | |
1221 | struct swap_extent *se; | |
1222 | struct swap_extent *new_se; | |
1223 | struct list_head *lh; | |
1224 | ||
11d31886 HD |
1225 | lh = sis->extent_list.prev; /* The highest page extent */ |
1226 | if (lh != &sis->extent_list) { | |
1da177e4 | 1227 | se = list_entry(lh, struct swap_extent, list); |
11d31886 HD |
1228 | BUG_ON(se->start_page + se->nr_pages != start_page); |
1229 | if (se->start_block + se->nr_pages == start_block) { | |
1da177e4 LT |
1230 | /* Merge it */ |
1231 | se->nr_pages += nr_pages; | |
1232 | return 0; | |
1233 | } | |
1da177e4 LT |
1234 | } |
1235 | ||
1236 | /* | |
1237 | * No merge. Insert a new extent, preserving ordering. | |
1238 | */ | |
1239 | new_se = kmalloc(sizeof(*se), GFP_KERNEL); | |
1240 | if (new_se == NULL) | |
1241 | return -ENOMEM; | |
1242 | new_se->start_page = start_page; | |
1243 | new_se->nr_pages = nr_pages; | |
1244 | new_se->start_block = start_block; | |
1245 | ||
11d31886 | 1246 | list_add_tail(&new_se->list, &sis->extent_list); |
53092a74 | 1247 | return 1; |
1da177e4 LT |
1248 | } |
1249 | ||
1250 | /* | |
1251 | * A `swap extent' is a simple thing which maps a contiguous range of pages | |
1252 | * onto a contiguous range of disk blocks. An ordered list of swap extents | |
1253 | * is built at swapon time and is then used at swap_writepage/swap_readpage | |
1254 | * time for locating where on disk a page belongs. | |
1255 | * | |
1256 | * If the swapfile is an S_ISBLK block device, a single extent is installed. | |
1257 | * This is done so that the main operating code can treat S_ISBLK and S_ISREG | |
1258 | * swap files identically. | |
1259 | * | |
1260 | * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap | |
1261 | * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK | |
1262 | * swapfiles are handled *identically* after swapon time. | |
1263 | * | |
1264 | * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks | |
1265 | * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If | |
1266 | * some stray blocks are found which do not fall within the PAGE_SIZE alignment | |
1267 | * requirements, they are simply tossed out - we will never use those blocks | |
1268 | * for swapping. | |
1269 | * | |
b0d9bcd4 | 1270 | * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This |
1da177e4 LT |
1271 | * prevents root from shooting her foot off by ftruncating an in-use swapfile, |
1272 | * which will scribble on the fs. | |
1273 | * | |
1274 | * The amount of disk space which a single swap extent represents varies. | |
1275 | * Typically it is in the 1-4 megabyte range. So we can have hundreds of | |
1276 | * extents in the list. To avoid much list walking, we cache the previous | |
1277 | * search location in `curr_swap_extent', and start new searches from there. | |
1278 | * This is extremely effective. The average number of iterations in | |
1279 | * map_swap_page() has been measured at about 0.3 per page. - akpm. | |
1280 | */ | |
53092a74 | 1281 | static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
1da177e4 LT |
1282 | { |
1283 | struct inode *inode; | |
1284 | unsigned blocks_per_page; | |
1285 | unsigned long page_no; | |
1286 | unsigned blkbits; | |
1287 | sector_t probe_block; | |
1288 | sector_t last_block; | |
53092a74 HD |
1289 | sector_t lowest_block = -1; |
1290 | sector_t highest_block = 0; | |
1291 | int nr_extents = 0; | |
1da177e4 LT |
1292 | int ret; |
1293 | ||
1294 | inode = sis->swap_file->f_mapping->host; | |
1295 | if (S_ISBLK(inode->i_mode)) { | |
1296 | ret = add_swap_extent(sis, 0, sis->max, 0); | |
53092a74 | 1297 | *span = sis->pages; |
1da177e4 LT |
1298 | goto done; |
1299 | } | |
1300 | ||
1301 | blkbits = inode->i_blkbits; | |
1302 | blocks_per_page = PAGE_SIZE >> blkbits; | |
1303 | ||
1304 | /* | |
1305 | * Map all the blocks into the extent list. This code doesn't try | |
1306 | * to be very smart. | |
1307 | */ | |
1308 | probe_block = 0; | |
1309 | page_no = 0; | |
1310 | last_block = i_size_read(inode) >> blkbits; | |
1311 | while ((probe_block + blocks_per_page) <= last_block && | |
1312 | page_no < sis->max) { | |
1313 | unsigned block_in_page; | |
1314 | sector_t first_block; | |
1315 | ||
1316 | first_block = bmap(inode, probe_block); | |
1317 | if (first_block == 0) | |
1318 | goto bad_bmap; | |
1319 | ||
1320 | /* | |
1321 | * It must be PAGE_SIZE aligned on-disk | |
1322 | */ | |
1323 | if (first_block & (blocks_per_page - 1)) { | |
1324 | probe_block++; | |
1325 | goto reprobe; | |
1326 | } | |
1327 | ||
1328 | for (block_in_page = 1; block_in_page < blocks_per_page; | |
1329 | block_in_page++) { | |
1330 | sector_t block; | |
1331 | ||
1332 | block = bmap(inode, probe_block + block_in_page); | |
1333 | if (block == 0) | |
1334 | goto bad_bmap; | |
1335 | if (block != first_block + block_in_page) { | |
1336 | /* Discontiguity */ | |
1337 | probe_block++; | |
1338 | goto reprobe; | |
1339 | } | |
1340 | } | |
1341 | ||
53092a74 HD |
1342 | first_block >>= (PAGE_SHIFT - blkbits); |
1343 | if (page_no) { /* exclude the header page */ | |
1344 | if (first_block < lowest_block) | |
1345 | lowest_block = first_block; | |
1346 | if (first_block > highest_block) | |
1347 | highest_block = first_block; | |
1348 | } | |
1349 | ||
1da177e4 LT |
1350 | /* |
1351 | * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks | |
1352 | */ | |
53092a74 HD |
1353 | ret = add_swap_extent(sis, page_no, 1, first_block); |
1354 | if (ret < 0) | |
1da177e4 | 1355 | goto out; |
53092a74 | 1356 | nr_extents += ret; |
1da177e4 LT |
1357 | page_no++; |
1358 | probe_block += blocks_per_page; | |
1359 | reprobe: | |
1360 | continue; | |
1361 | } | |
53092a74 HD |
1362 | ret = nr_extents; |
1363 | *span = 1 + highest_block - lowest_block; | |
1da177e4 | 1364 | if (page_no == 0) |
e2244ec2 | 1365 | page_no = 1; /* force Empty message */ |
1da177e4 | 1366 | sis->max = page_no; |
e2244ec2 | 1367 | sis->pages = page_no - 1; |
1da177e4 LT |
1368 | sis->highest_bit = page_no - 1; |
1369 | done: | |
1370 | sis->curr_swap_extent = list_entry(sis->extent_list.prev, | |
1371 | struct swap_extent, list); | |
1372 | goto out; | |
1373 | bad_bmap: | |
1374 | printk(KERN_ERR "swapon: swapfile has holes\n"); | |
1375 | ret = -EINVAL; | |
1376 | out: | |
1377 | return ret; | |
1378 | } | |
1379 | ||
c4ea37c2 | 1380 | SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) |
1da177e4 LT |
1381 | { |
1382 | struct swap_info_struct * p = NULL; | |
1383 | unsigned short *swap_map; | |
1384 | struct file *swap_file, *victim; | |
1385 | struct address_space *mapping; | |
1386 | struct inode *inode; | |
1387 | char * pathname; | |
1388 | int i, type, prev; | |
1389 | int err; | |
886bb7e9 | 1390 | |
1da177e4 LT |
1391 | if (!capable(CAP_SYS_ADMIN)) |
1392 | return -EPERM; | |
1393 | ||
1394 | pathname = getname(specialfile); | |
1395 | err = PTR_ERR(pathname); | |
1396 | if (IS_ERR(pathname)) | |
1397 | goto out; | |
1398 | ||
1399 | victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0); | |
1400 | putname(pathname); | |
1401 | err = PTR_ERR(victim); | |
1402 | if (IS_ERR(victim)) | |
1403 | goto out; | |
1404 | ||
1405 | mapping = victim->f_mapping; | |
1406 | prev = -1; | |
5d337b91 | 1407 | spin_lock(&swap_lock); |
1da177e4 LT |
1408 | for (type = swap_list.head; type >= 0; type = swap_info[type].next) { |
1409 | p = swap_info + type; | |
22c6f8fd | 1410 | if (p->flags & SWP_WRITEOK) { |
1da177e4 LT |
1411 | if (p->swap_file->f_mapping == mapping) |
1412 | break; | |
1413 | } | |
1414 | prev = type; | |
1415 | } | |
1416 | if (type < 0) { | |
1417 | err = -EINVAL; | |
5d337b91 | 1418 | spin_unlock(&swap_lock); |
1da177e4 LT |
1419 | goto out_dput; |
1420 | } | |
1421 | if (!security_vm_enough_memory(p->pages)) | |
1422 | vm_unacct_memory(p->pages); | |
1423 | else { | |
1424 | err = -ENOMEM; | |
5d337b91 | 1425 | spin_unlock(&swap_lock); |
1da177e4 LT |
1426 | goto out_dput; |
1427 | } | |
1428 | if (prev < 0) { | |
1429 | swap_list.head = p->next; | |
1430 | } else { | |
1431 | swap_info[prev].next = p->next; | |
1432 | } | |
1433 | if (type == swap_list.next) { | |
1434 | /* just pick something that's safe... */ | |
1435 | swap_list.next = swap_list.head; | |
1436 | } | |
78ecba08 HD |
1437 | if (p->prio < 0) { |
1438 | for (i = p->next; i >= 0; i = swap_info[i].next) | |
1439 | swap_info[i].prio = p->prio--; | |
1440 | least_priority++; | |
1441 | } | |
1da177e4 LT |
1442 | nr_swap_pages -= p->pages; |
1443 | total_swap_pages -= p->pages; | |
1444 | p->flags &= ~SWP_WRITEOK; | |
5d337b91 | 1445 | spin_unlock(&swap_lock); |
fb4f88dc | 1446 | |
1da177e4 LT |
1447 | current->flags |= PF_SWAPOFF; |
1448 | err = try_to_unuse(type); | |
1449 | current->flags &= ~PF_SWAPOFF; | |
1450 | ||
1da177e4 LT |
1451 | if (err) { |
1452 | /* re-insert swap space back into swap_list */ | |
5d337b91 | 1453 | spin_lock(&swap_lock); |
78ecba08 HD |
1454 | if (p->prio < 0) |
1455 | p->prio = --least_priority; | |
1456 | prev = -1; | |
1457 | for (i = swap_list.head; i >= 0; i = swap_info[i].next) { | |
1da177e4 LT |
1458 | if (p->prio >= swap_info[i].prio) |
1459 | break; | |
78ecba08 HD |
1460 | prev = i; |
1461 | } | |
1da177e4 LT |
1462 | p->next = i; |
1463 | if (prev < 0) | |
1464 | swap_list.head = swap_list.next = p - swap_info; | |
1465 | else | |
1466 | swap_info[prev].next = p - swap_info; | |
1467 | nr_swap_pages += p->pages; | |
1468 | total_swap_pages += p->pages; | |
1469 | p->flags |= SWP_WRITEOK; | |
5d337b91 | 1470 | spin_unlock(&swap_lock); |
1da177e4 LT |
1471 | goto out_dput; |
1472 | } | |
52b7efdb HD |
1473 | |
1474 | /* wait for any unplug function to finish */ | |
1475 | down_write(&swap_unplug_sem); | |
1476 | up_write(&swap_unplug_sem); | |
1477 | ||
5d337b91 | 1478 | destroy_swap_extents(p); |
fc0abb14 | 1479 | mutex_lock(&swapon_mutex); |
5d337b91 HD |
1480 | spin_lock(&swap_lock); |
1481 | drain_mmlist(); | |
1482 | ||
52b7efdb | 1483 | /* wait for anyone still in scan_swap_map */ |
52b7efdb HD |
1484 | p->highest_bit = 0; /* cuts scans short */ |
1485 | while (p->flags >= SWP_SCANNING) { | |
5d337b91 | 1486 | spin_unlock(&swap_lock); |
13e4b57f | 1487 | schedule_timeout_uninterruptible(1); |
5d337b91 | 1488 | spin_lock(&swap_lock); |
52b7efdb | 1489 | } |
52b7efdb | 1490 | |
1da177e4 LT |
1491 | swap_file = p->swap_file; |
1492 | p->swap_file = NULL; | |
1493 | p->max = 0; | |
1494 | swap_map = p->swap_map; | |
1495 | p->swap_map = NULL; | |
1496 | p->flags = 0; | |
5d337b91 | 1497 | spin_unlock(&swap_lock); |
fc0abb14 | 1498 | mutex_unlock(&swapon_mutex); |
1da177e4 | 1499 | vfree(swap_map); |
27a7faa0 KH |
1500 | /* Destroy swap account informatin */ |
1501 | swap_cgroup_swapoff(type); | |
1502 | ||
1da177e4 LT |
1503 | inode = mapping->host; |
1504 | if (S_ISBLK(inode->i_mode)) { | |
1505 | struct block_device *bdev = I_BDEV(inode); | |
1506 | set_blocksize(bdev, p->old_block_size); | |
1507 | bd_release(bdev); | |
1508 | } else { | |
1b1dcc1b | 1509 | mutex_lock(&inode->i_mutex); |
1da177e4 | 1510 | inode->i_flags &= ~S_SWAPFILE; |
1b1dcc1b | 1511 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
1512 | } |
1513 | filp_close(swap_file, NULL); | |
1514 | err = 0; | |
1515 | ||
1516 | out_dput: | |
1517 | filp_close(victim, NULL); | |
1518 | out: | |
1519 | return err; | |
1520 | } | |
1521 | ||
1522 | #ifdef CONFIG_PROC_FS | |
1523 | /* iterator */ | |
1524 | static void *swap_start(struct seq_file *swap, loff_t *pos) | |
1525 | { | |
1526 | struct swap_info_struct *ptr = swap_info; | |
1527 | int i; | |
1528 | loff_t l = *pos; | |
1529 | ||
fc0abb14 | 1530 | mutex_lock(&swapon_mutex); |
1da177e4 | 1531 | |
881e4aab SS |
1532 | if (!l) |
1533 | return SEQ_START_TOKEN; | |
1534 | ||
1da177e4 LT |
1535 | for (i = 0; i < nr_swapfiles; i++, ptr++) { |
1536 | if (!(ptr->flags & SWP_USED) || !ptr->swap_map) | |
1537 | continue; | |
881e4aab | 1538 | if (!--l) |
1da177e4 LT |
1539 | return ptr; |
1540 | } | |
1541 | ||
1542 | return NULL; | |
1543 | } | |
1544 | ||
1545 | static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) | |
1546 | { | |
881e4aab | 1547 | struct swap_info_struct *ptr; |
1da177e4 LT |
1548 | struct swap_info_struct *endptr = swap_info + nr_swapfiles; |
1549 | ||
881e4aab SS |
1550 | if (v == SEQ_START_TOKEN) |
1551 | ptr = swap_info; | |
1552 | else { | |
1553 | ptr = v; | |
1554 | ptr++; | |
1555 | } | |
1556 | ||
1557 | for (; ptr < endptr; ptr++) { | |
1da177e4 LT |
1558 | if (!(ptr->flags & SWP_USED) || !ptr->swap_map) |
1559 | continue; | |
1560 | ++*pos; | |
1561 | return ptr; | |
1562 | } | |
1563 | ||
1564 | return NULL; | |
1565 | } | |
1566 | ||
1567 | static void swap_stop(struct seq_file *swap, void *v) | |
1568 | { | |
fc0abb14 | 1569 | mutex_unlock(&swapon_mutex); |
1da177e4 LT |
1570 | } |
1571 | ||
1572 | static int swap_show(struct seq_file *swap, void *v) | |
1573 | { | |
1574 | struct swap_info_struct *ptr = v; | |
1575 | struct file *file; | |
1576 | int len; | |
1577 | ||
881e4aab SS |
1578 | if (ptr == SEQ_START_TOKEN) { |
1579 | seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n"); | |
1580 | return 0; | |
1581 | } | |
1da177e4 LT |
1582 | |
1583 | file = ptr->swap_file; | |
c32c2f63 | 1584 | len = seq_path(swap, &file->f_path, " \t\n\\"); |
6eb396dc | 1585 | seq_printf(swap, "%*s%s\t%u\t%u\t%d\n", |
886bb7e9 HD |
1586 | len < 40 ? 40 - len : 1, " ", |
1587 | S_ISBLK(file->f_path.dentry->d_inode->i_mode) ? | |
1da177e4 | 1588 | "partition" : "file\t", |
886bb7e9 HD |
1589 | ptr->pages << (PAGE_SHIFT - 10), |
1590 | ptr->inuse_pages << (PAGE_SHIFT - 10), | |
1591 | ptr->prio); | |
1da177e4 LT |
1592 | return 0; |
1593 | } | |
1594 | ||
15ad7cdc | 1595 | static const struct seq_operations swaps_op = { |
1da177e4 LT |
1596 | .start = swap_start, |
1597 | .next = swap_next, | |
1598 | .stop = swap_stop, | |
1599 | .show = swap_show | |
1600 | }; | |
1601 | ||
1602 | static int swaps_open(struct inode *inode, struct file *file) | |
1603 | { | |
1604 | return seq_open(file, &swaps_op); | |
1605 | } | |
1606 | ||
15ad7cdc | 1607 | static const struct file_operations proc_swaps_operations = { |
1da177e4 LT |
1608 | .open = swaps_open, |
1609 | .read = seq_read, | |
1610 | .llseek = seq_lseek, | |
1611 | .release = seq_release, | |
1612 | }; | |
1613 | ||
1614 | static int __init procswaps_init(void) | |
1615 | { | |
3d71f86f | 1616 | proc_create("swaps", 0, NULL, &proc_swaps_operations); |
1da177e4 LT |
1617 | return 0; |
1618 | } | |
1619 | __initcall(procswaps_init); | |
1620 | #endif /* CONFIG_PROC_FS */ | |
1621 | ||
1796316a JB |
1622 | #ifdef MAX_SWAPFILES_CHECK |
1623 | static int __init max_swapfiles_check(void) | |
1624 | { | |
1625 | MAX_SWAPFILES_CHECK(); | |
1626 | return 0; | |
1627 | } | |
1628 | late_initcall(max_swapfiles_check); | |
1629 | #endif | |
1630 | ||
1da177e4 LT |
1631 | /* |
1632 | * Written 01/25/92 by Simmule Turner, heavily changed by Linus. | |
1633 | * | |
1634 | * The swapon system call | |
1635 | */ | |
c4ea37c2 | 1636 | SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) |
1da177e4 LT |
1637 | { |
1638 | struct swap_info_struct * p; | |
1639 | char *name = NULL; | |
1640 | struct block_device *bdev = NULL; | |
1641 | struct file *swap_file = NULL; | |
1642 | struct address_space *mapping; | |
1643 | unsigned int type; | |
1644 | int i, prev; | |
1645 | int error; | |
1da177e4 | 1646 | union swap_header *swap_header = NULL; |
6eb396dc HD |
1647 | unsigned int nr_good_pages = 0; |
1648 | int nr_extents = 0; | |
53092a74 | 1649 | sector_t span; |
1da177e4 | 1650 | unsigned long maxpages = 1; |
73fd8748 | 1651 | unsigned long swapfilepages; |
78ecba08 | 1652 | unsigned short *swap_map = NULL; |
1da177e4 LT |
1653 | struct page *page = NULL; |
1654 | struct inode *inode = NULL; | |
1655 | int did_down = 0; | |
1656 | ||
1657 | if (!capable(CAP_SYS_ADMIN)) | |
1658 | return -EPERM; | |
5d337b91 | 1659 | spin_lock(&swap_lock); |
1da177e4 LT |
1660 | p = swap_info; |
1661 | for (type = 0 ; type < nr_swapfiles ; type++,p++) | |
1662 | if (!(p->flags & SWP_USED)) | |
1663 | break; | |
1664 | error = -EPERM; | |
0697212a | 1665 | if (type >= MAX_SWAPFILES) { |
5d337b91 | 1666 | spin_unlock(&swap_lock); |
1da177e4 LT |
1667 | goto out; |
1668 | } | |
1669 | if (type >= nr_swapfiles) | |
1670 | nr_swapfiles = type+1; | |
78ecba08 | 1671 | memset(p, 0, sizeof(*p)); |
1da177e4 LT |
1672 | INIT_LIST_HEAD(&p->extent_list); |
1673 | p->flags = SWP_USED; | |
1da177e4 | 1674 | p->next = -1; |
5d337b91 | 1675 | spin_unlock(&swap_lock); |
1da177e4 LT |
1676 | name = getname(specialfile); |
1677 | error = PTR_ERR(name); | |
1678 | if (IS_ERR(name)) { | |
1679 | name = NULL; | |
1680 | goto bad_swap_2; | |
1681 | } | |
1682 | swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0); | |
1683 | error = PTR_ERR(swap_file); | |
1684 | if (IS_ERR(swap_file)) { | |
1685 | swap_file = NULL; | |
1686 | goto bad_swap_2; | |
1687 | } | |
1688 | ||
1689 | p->swap_file = swap_file; | |
1690 | mapping = swap_file->f_mapping; | |
1691 | inode = mapping->host; | |
1692 | ||
1693 | error = -EBUSY; | |
1694 | for (i = 0; i < nr_swapfiles; i++) { | |
1695 | struct swap_info_struct *q = &swap_info[i]; | |
1696 | ||
1697 | if (i == type || !q->swap_file) | |
1698 | continue; | |
1699 | if (mapping == q->swap_file->f_mapping) | |
1700 | goto bad_swap; | |
1701 | } | |
1702 | ||
1703 | error = -EINVAL; | |
1704 | if (S_ISBLK(inode->i_mode)) { | |
1705 | bdev = I_BDEV(inode); | |
1706 | error = bd_claim(bdev, sys_swapon); | |
1707 | if (error < 0) { | |
1708 | bdev = NULL; | |
f7b3a435 | 1709 | error = -EINVAL; |
1da177e4 LT |
1710 | goto bad_swap; |
1711 | } | |
1712 | p->old_block_size = block_size(bdev); | |
1713 | error = set_blocksize(bdev, PAGE_SIZE); | |
1714 | if (error < 0) | |
1715 | goto bad_swap; | |
1716 | p->bdev = bdev; | |
1717 | } else if (S_ISREG(inode->i_mode)) { | |
1718 | p->bdev = inode->i_sb->s_bdev; | |
1b1dcc1b | 1719 | mutex_lock(&inode->i_mutex); |
1da177e4 LT |
1720 | did_down = 1; |
1721 | if (IS_SWAPFILE(inode)) { | |
1722 | error = -EBUSY; | |
1723 | goto bad_swap; | |
1724 | } | |
1725 | } else { | |
1726 | goto bad_swap; | |
1727 | } | |
1728 | ||
73fd8748 | 1729 | swapfilepages = i_size_read(inode) >> PAGE_SHIFT; |
1da177e4 LT |
1730 | |
1731 | /* | |
1732 | * Read the swap header. | |
1733 | */ | |
1734 | if (!mapping->a_ops->readpage) { | |
1735 | error = -EINVAL; | |
1736 | goto bad_swap; | |
1737 | } | |
090d2b18 | 1738 | page = read_mapping_page(mapping, 0, swap_file); |
1da177e4 LT |
1739 | if (IS_ERR(page)) { |
1740 | error = PTR_ERR(page); | |
1741 | goto bad_swap; | |
1742 | } | |
81e33971 | 1743 | swap_header = kmap(page); |
1da177e4 | 1744 | |
81e33971 | 1745 | if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) { |
e97a3111 | 1746 | printk(KERN_ERR "Unable to find swap-space signature\n"); |
1da177e4 LT |
1747 | error = -EINVAL; |
1748 | goto bad_swap; | |
1749 | } | |
886bb7e9 | 1750 | |
81e33971 HD |
1751 | /* swap partition endianess hack... */ |
1752 | if (swab32(swap_header->info.version) == 1) { | |
1753 | swab32s(&swap_header->info.version); | |
1754 | swab32s(&swap_header->info.last_page); | |
1755 | swab32s(&swap_header->info.nr_badpages); | |
1756 | for (i = 0; i < swap_header->info.nr_badpages; i++) | |
1757 | swab32s(&swap_header->info.badpages[i]); | |
1758 | } | |
1759 | /* Check the swap header's sub-version */ | |
1760 | if (swap_header->info.version != 1) { | |
1761 | printk(KERN_WARNING | |
1762 | "Unable to handle swap header version %d\n", | |
1763 | swap_header->info.version); | |
1da177e4 LT |
1764 | error = -EINVAL; |
1765 | goto bad_swap; | |
81e33971 | 1766 | } |
1da177e4 | 1767 | |
81e33971 HD |
1768 | p->lowest_bit = 1; |
1769 | p->cluster_next = 1; | |
52b7efdb | 1770 | |
81e33971 HD |
1771 | /* |
1772 | * Find out how many pages are allowed for a single swap | |
1773 | * device. There are two limiting factors: 1) the number of | |
1774 | * bits for the swap offset in the swp_entry_t type and | |
1775 | * 2) the number of bits in the a swap pte as defined by | |
1776 | * the different architectures. In order to find the | |
1777 | * largest possible bit mask a swap entry with swap type 0 | |
1778 | * and swap offset ~0UL is created, encoded to a swap pte, | |
1779 | * decoded to a swp_entry_t again and finally the swap | |
1780 | * offset is extracted. This will mask all the bits from | |
1781 | * the initial ~0UL mask that can't be encoded in either | |
1782 | * the swp_entry_t or the architecture definition of a | |
1783 | * swap pte. | |
1784 | */ | |
1785 | maxpages = swp_offset(pte_to_swp_entry( | |
1786 | swp_entry_to_pte(swp_entry(0, ~0UL)))) - 1; | |
1787 | if (maxpages > swap_header->info.last_page) | |
1788 | maxpages = swap_header->info.last_page; | |
1789 | p->highest_bit = maxpages - 1; | |
1da177e4 | 1790 | |
81e33971 HD |
1791 | error = -EINVAL; |
1792 | if (!maxpages) | |
1793 | goto bad_swap; | |
1794 | if (swapfilepages && maxpages > swapfilepages) { | |
1795 | printk(KERN_WARNING | |
1796 | "Swap area shorter than signature indicates\n"); | |
1797 | goto bad_swap; | |
1798 | } | |
1799 | if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) | |
1800 | goto bad_swap; | |
1801 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) | |
1802 | goto bad_swap; | |
cd105df4 | 1803 | |
81e33971 HD |
1804 | /* OK, set up the swap map and apply the bad block list */ |
1805 | swap_map = vmalloc(maxpages * sizeof(short)); | |
1806 | if (!swap_map) { | |
1807 | error = -ENOMEM; | |
1808 | goto bad_swap; | |
1809 | } | |
1da177e4 | 1810 | |
81e33971 HD |
1811 | memset(swap_map, 0, maxpages * sizeof(short)); |
1812 | for (i = 0; i < swap_header->info.nr_badpages; i++) { | |
1813 | int page_nr = swap_header->info.badpages[i]; | |
1814 | if (page_nr <= 0 || page_nr >= swap_header->info.last_page) { | |
1815 | error = -EINVAL; | |
1da177e4 | 1816 | goto bad_swap; |
81e33971 HD |
1817 | } |
1818 | swap_map[page_nr] = SWAP_MAP_BAD; | |
1da177e4 | 1819 | } |
27a7faa0 KH |
1820 | |
1821 | error = swap_cgroup_swapon(type, maxpages); | |
1822 | if (error) | |
1823 | goto bad_swap; | |
1824 | ||
81e33971 HD |
1825 | nr_good_pages = swap_header->info.last_page - |
1826 | swap_header->info.nr_badpages - | |
1827 | 1 /* header page */; | |
e2244ec2 | 1828 | |
e2244ec2 | 1829 | if (nr_good_pages) { |
78ecba08 | 1830 | swap_map[0] = SWAP_MAP_BAD; |
e2244ec2 HD |
1831 | p->max = maxpages; |
1832 | p->pages = nr_good_pages; | |
53092a74 HD |
1833 | nr_extents = setup_swap_extents(p, &span); |
1834 | if (nr_extents < 0) { | |
1835 | error = nr_extents; | |
e2244ec2 | 1836 | goto bad_swap; |
53092a74 | 1837 | } |
e2244ec2 HD |
1838 | nr_good_pages = p->pages; |
1839 | } | |
1da177e4 LT |
1840 | if (!nr_good_pages) { |
1841 | printk(KERN_WARNING "Empty swap-file\n"); | |
1842 | error = -EINVAL; | |
1843 | goto bad_swap; | |
1844 | } | |
1da177e4 | 1845 | |
20137a49 HD |
1846 | if (blk_queue_nonrot(bdev_get_queue(p->bdev))) { |
1847 | p->flags |= SWP_SOLIDSTATE; | |
20137a49 HD |
1848 | p->cluster_next = 1 + (random32() % p->highest_bit); |
1849 | } | |
6a6ba831 HD |
1850 | if (discard_swap(p) == 0) |
1851 | p->flags |= SWP_DISCARDABLE; | |
1852 | ||
fc0abb14 | 1853 | mutex_lock(&swapon_mutex); |
5d337b91 | 1854 | spin_lock(&swap_lock); |
78ecba08 HD |
1855 | if (swap_flags & SWAP_FLAG_PREFER) |
1856 | p->prio = | |
1857 | (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; | |
1858 | else | |
1859 | p->prio = --least_priority; | |
1860 | p->swap_map = swap_map; | |
22c6f8fd | 1861 | p->flags |= SWP_WRITEOK; |
1da177e4 LT |
1862 | nr_swap_pages += nr_good_pages; |
1863 | total_swap_pages += nr_good_pages; | |
53092a74 | 1864 | |
6eb396dc | 1865 | printk(KERN_INFO "Adding %uk swap on %s. " |
20137a49 | 1866 | "Priority:%d extents:%d across:%lluk %s%s\n", |
53092a74 | 1867 | nr_good_pages<<(PAGE_SHIFT-10), name, p->prio, |
6a6ba831 | 1868 | nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), |
20137a49 HD |
1869 | (p->flags & SWP_SOLIDSTATE) ? "SS" : "", |
1870 | (p->flags & SWP_DISCARDABLE) ? "D" : ""); | |
1da177e4 LT |
1871 | |
1872 | /* insert swap space into swap_list: */ | |
1873 | prev = -1; | |
1874 | for (i = swap_list.head; i >= 0; i = swap_info[i].next) { | |
1875 | if (p->prio >= swap_info[i].prio) { | |
1876 | break; | |
1877 | } | |
1878 | prev = i; | |
1879 | } | |
1880 | p->next = i; | |
1881 | if (prev < 0) { | |
1882 | swap_list.head = swap_list.next = p - swap_info; | |
1883 | } else { | |
1884 | swap_info[prev].next = p - swap_info; | |
1885 | } | |
5d337b91 | 1886 | spin_unlock(&swap_lock); |
fc0abb14 | 1887 | mutex_unlock(&swapon_mutex); |
1da177e4 LT |
1888 | error = 0; |
1889 | goto out; | |
1890 | bad_swap: | |
1891 | if (bdev) { | |
1892 | set_blocksize(bdev, p->old_block_size); | |
1893 | bd_release(bdev); | |
1894 | } | |
4cd3bb10 | 1895 | destroy_swap_extents(p); |
27a7faa0 | 1896 | swap_cgroup_swapoff(type); |
1da177e4 | 1897 | bad_swap_2: |
5d337b91 | 1898 | spin_lock(&swap_lock); |
1da177e4 | 1899 | p->swap_file = NULL; |
1da177e4 | 1900 | p->flags = 0; |
5d337b91 | 1901 | spin_unlock(&swap_lock); |
1da177e4 LT |
1902 | vfree(swap_map); |
1903 | if (swap_file) | |
1904 | filp_close(swap_file, NULL); | |
1905 | out: | |
1906 | if (page && !IS_ERR(page)) { | |
1907 | kunmap(page); | |
1908 | page_cache_release(page); | |
1909 | } | |
1910 | if (name) | |
1911 | putname(name); | |
1912 | if (did_down) { | |
1913 | if (!error) | |
1914 | inode->i_flags |= S_SWAPFILE; | |
1b1dcc1b | 1915 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
1916 | } |
1917 | return error; | |
1918 | } | |
1919 | ||
1920 | void si_swapinfo(struct sysinfo *val) | |
1921 | { | |
1922 | unsigned int i; | |
1923 | unsigned long nr_to_be_unused = 0; | |
1924 | ||
5d337b91 | 1925 | spin_lock(&swap_lock); |
1da177e4 LT |
1926 | for (i = 0; i < nr_swapfiles; i++) { |
1927 | if (!(swap_info[i].flags & SWP_USED) || | |
1928 | (swap_info[i].flags & SWP_WRITEOK)) | |
1929 | continue; | |
1930 | nr_to_be_unused += swap_info[i].inuse_pages; | |
1931 | } | |
1932 | val->freeswap = nr_swap_pages + nr_to_be_unused; | |
1933 | val->totalswap = total_swap_pages + nr_to_be_unused; | |
5d337b91 | 1934 | spin_unlock(&swap_lock); |
1da177e4 LT |
1935 | } |
1936 | ||
1937 | /* | |
1938 | * Verify that a swap entry is valid and increment its swap map count. | |
1939 | * | |
1940 | * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as | |
1941 | * "permanent", but will be reclaimed by the next swapoff. | |
1942 | */ | |
1943 | int swap_duplicate(swp_entry_t entry) | |
1944 | { | |
1945 | struct swap_info_struct * p; | |
1946 | unsigned long offset, type; | |
1947 | int result = 0; | |
1948 | ||
0697212a CL |
1949 | if (is_migration_entry(entry)) |
1950 | return 1; | |
1951 | ||
1da177e4 LT |
1952 | type = swp_type(entry); |
1953 | if (type >= nr_swapfiles) | |
1954 | goto bad_file; | |
1955 | p = type + swap_info; | |
1956 | offset = swp_offset(entry); | |
1957 | ||
5d337b91 | 1958 | spin_lock(&swap_lock); |
1da177e4 LT |
1959 | if (offset < p->max && p->swap_map[offset]) { |
1960 | if (p->swap_map[offset] < SWAP_MAP_MAX - 1) { | |
1961 | p->swap_map[offset]++; | |
1962 | result = 1; | |
1963 | } else if (p->swap_map[offset] <= SWAP_MAP_MAX) { | |
1964 | if (swap_overflow++ < 5) | |
1965 | printk(KERN_WARNING "swap_dup: swap entry overflow\n"); | |
1966 | p->swap_map[offset] = SWAP_MAP_MAX; | |
1967 | result = 1; | |
1968 | } | |
1969 | } | |
5d337b91 | 1970 | spin_unlock(&swap_lock); |
1da177e4 LT |
1971 | out: |
1972 | return result; | |
1973 | ||
1974 | bad_file: | |
1975 | printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val); | |
1976 | goto out; | |
1977 | } | |
1978 | ||
1979 | struct swap_info_struct * | |
1980 | get_swap_info_struct(unsigned type) | |
1981 | { | |
1982 | return &swap_info[type]; | |
1983 | } | |
1984 | ||
1985 | /* | |
5d337b91 | 1986 | * swap_lock prevents swap_map being freed. Don't grab an extra |
1da177e4 LT |
1987 | * reference on the swaphandle, it doesn't matter if it becomes unused. |
1988 | */ | |
1989 | int valid_swaphandles(swp_entry_t entry, unsigned long *offset) | |
1990 | { | |
8952898b | 1991 | struct swap_info_struct *si; |
3f9e7949 | 1992 | int our_page_cluster = page_cluster; |
8952898b HD |
1993 | pgoff_t target, toff; |
1994 | pgoff_t base, end; | |
1995 | int nr_pages = 0; | |
1da177e4 | 1996 | |
3f9e7949 | 1997 | if (!our_page_cluster) /* no readahead */ |
1da177e4 | 1998 | return 0; |
8952898b HD |
1999 | |
2000 | si = &swap_info[swp_type(entry)]; | |
2001 | target = swp_offset(entry); | |
2002 | base = (target >> our_page_cluster) << our_page_cluster; | |
2003 | end = base + (1 << our_page_cluster); | |
2004 | if (!base) /* first page is swap header */ | |
2005 | base++; | |
1da177e4 | 2006 | |
5d337b91 | 2007 | spin_lock(&swap_lock); |
8952898b HD |
2008 | if (end > si->max) /* don't go beyond end of map */ |
2009 | end = si->max; | |
2010 | ||
2011 | /* Count contiguous allocated slots above our target */ | |
2012 | for (toff = target; ++toff < end; nr_pages++) { | |
2013 | /* Don't read in free or bad pages */ | |
2014 | if (!si->swap_map[toff]) | |
2015 | break; | |
2016 | if (si->swap_map[toff] == SWAP_MAP_BAD) | |
1da177e4 | 2017 | break; |
8952898b HD |
2018 | } |
2019 | /* Count contiguous allocated slots below our target */ | |
2020 | for (toff = target; --toff >= base; nr_pages++) { | |
1da177e4 | 2021 | /* Don't read in free or bad pages */ |
8952898b | 2022 | if (!si->swap_map[toff]) |
1da177e4 | 2023 | break; |
8952898b | 2024 | if (si->swap_map[toff] == SWAP_MAP_BAD) |
1da177e4 | 2025 | break; |
8952898b | 2026 | } |
5d337b91 | 2027 | spin_unlock(&swap_lock); |
8952898b HD |
2028 | |
2029 | /* | |
2030 | * Indicate starting offset, and return number of pages to get: | |
2031 | * if only 1, say 0, since there's then no readahead to be done. | |
2032 | */ | |
2033 | *offset = ++toff; | |
2034 | return nr_pages? ++nr_pages: 0; | |
1da177e4 | 2035 | } |