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