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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/swapfile.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * Swap reorganised 29.12.95, Stephen Tweedie | |
6 | */ | |
7 | ||
1da177e4 LT |
8 | #include <linux/mm.h> |
9 | #include <linux/hugetlb.h> | |
10 | #include <linux/mman.h> | |
11 | #include <linux/slab.h> | |
12 | #include <linux/kernel_stat.h> | |
13 | #include <linux/swap.h> | |
14 | #include <linux/vmalloc.h> | |
15 | #include <linux/pagemap.h> | |
16 | #include <linux/namei.h> | |
17 | #include <linux/shm.h> | |
18 | #include <linux/blkdev.h> | |
20137a49 | 19 | #include <linux/random.h> |
1da177e4 LT |
20 | #include <linux/writeback.h> |
21 | #include <linux/proc_fs.h> | |
22 | #include <linux/seq_file.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/module.h> | |
25 | #include <linux/rmap.h> | |
26 | #include <linux/security.h> | |
27 | #include <linux/backing-dev.h> | |
fc0abb14 | 28 | #include <linux/mutex.h> |
c59ede7b | 29 | #include <linux/capability.h> |
1da177e4 | 30 | #include <linux/syscalls.h> |
8a9f3ccd | 31 | #include <linux/memcontrol.h> |
1da177e4 LT |
32 | |
33 | #include <asm/pgtable.h> | |
34 | #include <asm/tlbflush.h> | |
35 | #include <linux/swapops.h> | |
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 | 55 | |
355cfa73 KH |
56 | /* For reference count accounting in swap_map */ |
57 | /* enum for swap_map[] handling. internal use only */ | |
58 | enum { | |
59 | SWAP_MAP = 0, /* ops for reference from swap users */ | |
60 | SWAP_CACHE, /* ops for reference from swap cache */ | |
61 | }; | |
62 | ||
63 | static inline int swap_count(unsigned short ent) | |
64 | { | |
65 | return ent & SWAP_COUNT_MASK; | |
66 | } | |
67 | ||
68 | static inline bool swap_has_cache(unsigned short ent) | |
69 | { | |
70 | return !!(ent & SWAP_HAS_CACHE); | |
71 | } | |
72 | ||
73 | static inline unsigned short encode_swapmap(int count, bool has_cache) | |
74 | { | |
75 | unsigned short ret = count; | |
76 | ||
77 | if (has_cache) | |
78 | return SWAP_HAS_CACHE | ret; | |
79 | return ret; | |
80 | } | |
81 | ||
82 | ||
1da177e4 LT |
83 | /* |
84 | * We need this because the bdev->unplug_fn can sleep and we cannot | |
5d337b91 | 85 | * hold swap_lock while calling the unplug_fn. And swap_lock |
fc0abb14 | 86 | * cannot be turned into a mutex. |
1da177e4 LT |
87 | */ |
88 | static DECLARE_RWSEM(swap_unplug_sem); | |
89 | ||
1da177e4 LT |
90 | void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page) |
91 | { | |
92 | swp_entry_t entry; | |
93 | ||
94 | down_read(&swap_unplug_sem); | |
4c21e2f2 | 95 | entry.val = page_private(page); |
1da177e4 LT |
96 | if (PageSwapCache(page)) { |
97 | struct block_device *bdev = swap_info[swp_type(entry)].bdev; | |
98 | struct backing_dev_info *bdi; | |
99 | ||
100 | /* | |
101 | * If the page is removed from swapcache from under us (with a | |
102 | * racy try_to_unuse/swapoff) we need an additional reference | |
4c21e2f2 HD |
103 | * count to avoid reading garbage from page_private(page) above. |
104 | * If the WARN_ON triggers during a swapoff it maybe the race | |
1da177e4 LT |
105 | * condition and it's harmless. However if it triggers without |
106 | * swapoff it signals a problem. | |
107 | */ | |
108 | WARN_ON(page_count(page) <= 1); | |
109 | ||
110 | bdi = bdev->bd_inode->i_mapping->backing_dev_info; | |
ba32311e | 111 | blk_run_backing_dev(bdi, page); |
1da177e4 LT |
112 | } |
113 | up_read(&swap_unplug_sem); | |
114 | } | |
115 | ||
6a6ba831 HD |
116 | /* |
117 | * swapon tell device that all the old swap contents can be discarded, | |
118 | * to allow the swap device to optimize its wear-levelling. | |
119 | */ | |
120 | static int discard_swap(struct swap_info_struct *si) | |
121 | { | |
122 | struct swap_extent *se; | |
123 | int err = 0; | |
124 | ||
125 | list_for_each_entry(se, &si->extent_list, list) { | |
126 | sector_t start_block = se->start_block << (PAGE_SHIFT - 9); | |
858a2990 | 127 | sector_t nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); |
6a6ba831 HD |
128 | |
129 | if (se->start_page == 0) { | |
130 | /* Do not discard the swap header page! */ | |
131 | start_block += 1 << (PAGE_SHIFT - 9); | |
132 | nr_blocks -= 1 << (PAGE_SHIFT - 9); | |
133 | if (!nr_blocks) | |
134 | continue; | |
135 | } | |
136 | ||
137 | err = blkdev_issue_discard(si->bdev, start_block, | |
138 | nr_blocks, GFP_KERNEL); | |
139 | if (err) | |
140 | break; | |
141 | ||
142 | cond_resched(); | |
143 | } | |
144 | return err; /* That will often be -EOPNOTSUPP */ | |
145 | } | |
146 | ||
7992fde7 HD |
147 | /* |
148 | * swap allocation tell device that a cluster of swap can now be discarded, | |
149 | * to allow the swap device to optimize its wear-levelling. | |
150 | */ | |
151 | static void discard_swap_cluster(struct swap_info_struct *si, | |
152 | pgoff_t start_page, pgoff_t nr_pages) | |
153 | { | |
154 | struct swap_extent *se = si->curr_swap_extent; | |
155 | int found_extent = 0; | |
156 | ||
157 | while (nr_pages) { | |
158 | struct list_head *lh; | |
159 | ||
160 | if (se->start_page <= start_page && | |
161 | start_page < se->start_page + se->nr_pages) { | |
162 | pgoff_t offset = start_page - se->start_page; | |
163 | sector_t start_block = se->start_block + offset; | |
858a2990 | 164 | sector_t nr_blocks = se->nr_pages - offset; |
7992fde7 HD |
165 | |
166 | if (nr_blocks > nr_pages) | |
167 | nr_blocks = nr_pages; | |
168 | start_page += nr_blocks; | |
169 | nr_pages -= nr_blocks; | |
170 | ||
171 | if (!found_extent++) | |
172 | si->curr_swap_extent = se; | |
173 | ||
174 | start_block <<= PAGE_SHIFT - 9; | |
175 | nr_blocks <<= PAGE_SHIFT - 9; | |
176 | if (blkdev_issue_discard(si->bdev, start_block, | |
177 | nr_blocks, GFP_NOIO)) | |
178 | break; | |
179 | } | |
180 | ||
181 | lh = se->list.next; | |
182 | if (lh == &si->extent_list) | |
183 | lh = lh->next; | |
184 | se = list_entry(lh, struct swap_extent, list); | |
185 | } | |
186 | } | |
187 | ||
188 | static int wait_for_discard(void *word) | |
189 | { | |
190 | schedule(); | |
191 | return 0; | |
192 | } | |
193 | ||
048c27fd HD |
194 | #define SWAPFILE_CLUSTER 256 |
195 | #define LATENCY_LIMIT 256 | |
196 | ||
355cfa73 KH |
197 | static inline unsigned long scan_swap_map(struct swap_info_struct *si, |
198 | int cache) | |
1da177e4 | 199 | { |
ebebbbe9 | 200 | unsigned long offset; |
c60aa176 | 201 | unsigned long scan_base; |
7992fde7 | 202 | unsigned long last_in_cluster = 0; |
048c27fd | 203 | int latency_ration = LATENCY_LIMIT; |
7992fde7 | 204 | int found_free_cluster = 0; |
7dfad418 | 205 | |
886bb7e9 | 206 | /* |
7dfad418 HD |
207 | * We try to cluster swap pages by allocating them sequentially |
208 | * in swap. Once we've allocated SWAPFILE_CLUSTER pages this | |
209 | * way, however, we resort to first-free allocation, starting | |
210 | * a new cluster. This prevents us from scattering swap pages | |
211 | * all over the entire swap partition, so that we reduce | |
212 | * overall disk seek times between swap pages. -- sct | |
213 | * But we do now try to find an empty cluster. -Andrea | |
c60aa176 | 214 | * And we let swap pages go all over an SSD partition. Hugh |
7dfad418 HD |
215 | */ |
216 | ||
52b7efdb | 217 | si->flags += SWP_SCANNING; |
c60aa176 | 218 | scan_base = offset = si->cluster_next; |
ebebbbe9 HD |
219 | |
220 | if (unlikely(!si->cluster_nr--)) { | |
221 | if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { | |
222 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
223 | goto checks; | |
224 | } | |
7992fde7 HD |
225 | if (si->flags & SWP_DISCARDABLE) { |
226 | /* | |
227 | * Start range check on racing allocations, in case | |
228 | * they overlap the cluster we eventually decide on | |
229 | * (we scan without swap_lock to allow preemption). | |
230 | * It's hardly conceivable that cluster_nr could be | |
231 | * wrapped during our scan, but don't depend on it. | |
232 | */ | |
233 | if (si->lowest_alloc) | |
234 | goto checks; | |
235 | si->lowest_alloc = si->max; | |
236 | si->highest_alloc = 0; | |
237 | } | |
5d337b91 | 238 | spin_unlock(&swap_lock); |
7dfad418 | 239 | |
c60aa176 HD |
240 | /* |
241 | * If seek is expensive, start searching for new cluster from | |
242 | * start of partition, to minimize the span of allocated swap. | |
243 | * But if seek is cheap, search from our current position, so | |
244 | * that swap is allocated from all over the partition: if the | |
245 | * Flash Translation Layer only remaps within limited zones, | |
246 | * we don't want to wear out the first zone too quickly. | |
247 | */ | |
248 | if (!(si->flags & SWP_SOLIDSTATE)) | |
249 | scan_base = offset = si->lowest_bit; | |
7dfad418 HD |
250 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
251 | ||
252 | /* Locate the first empty (unaligned) cluster */ | |
253 | for (; last_in_cluster <= si->highest_bit; offset++) { | |
1da177e4 | 254 | if (si->swap_map[offset]) |
7dfad418 HD |
255 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
256 | else if (offset == last_in_cluster) { | |
5d337b91 | 257 | spin_lock(&swap_lock); |
ebebbbe9 HD |
258 | offset -= SWAPFILE_CLUSTER - 1; |
259 | si->cluster_next = offset; | |
260 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
7992fde7 | 261 | found_free_cluster = 1; |
ebebbbe9 | 262 | goto checks; |
1da177e4 | 263 | } |
048c27fd HD |
264 | if (unlikely(--latency_ration < 0)) { |
265 | cond_resched(); | |
266 | latency_ration = LATENCY_LIMIT; | |
267 | } | |
7dfad418 | 268 | } |
ebebbbe9 HD |
269 | |
270 | offset = si->lowest_bit; | |
c60aa176 HD |
271 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
272 | ||
273 | /* Locate the first empty (unaligned) cluster */ | |
274 | for (; last_in_cluster < scan_base; offset++) { | |
275 | if (si->swap_map[offset]) | |
276 | last_in_cluster = offset + SWAPFILE_CLUSTER; | |
277 | else if (offset == last_in_cluster) { | |
278 | spin_lock(&swap_lock); | |
279 | offset -= SWAPFILE_CLUSTER - 1; | |
280 | si->cluster_next = offset; | |
281 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
282 | found_free_cluster = 1; | |
283 | goto checks; | |
284 | } | |
285 | if (unlikely(--latency_ration < 0)) { | |
286 | cond_resched(); | |
287 | latency_ration = LATENCY_LIMIT; | |
288 | } | |
289 | } | |
290 | ||
291 | offset = scan_base; | |
5d337b91 | 292 | spin_lock(&swap_lock); |
ebebbbe9 | 293 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
7992fde7 | 294 | si->lowest_alloc = 0; |
1da177e4 | 295 | } |
7dfad418 | 296 | |
ebebbbe9 HD |
297 | checks: |
298 | if (!(si->flags & SWP_WRITEOK)) | |
52b7efdb | 299 | goto no_page; |
7dfad418 HD |
300 | if (!si->highest_bit) |
301 | goto no_page; | |
ebebbbe9 | 302 | if (offset > si->highest_bit) |
c60aa176 | 303 | scan_base = offset = si->lowest_bit; |
ebebbbe9 HD |
304 | if (si->swap_map[offset]) |
305 | goto scan; | |
306 | ||
307 | if (offset == si->lowest_bit) | |
308 | si->lowest_bit++; | |
309 | if (offset == si->highest_bit) | |
310 | si->highest_bit--; | |
311 | si->inuse_pages++; | |
312 | if (si->inuse_pages == si->pages) { | |
313 | si->lowest_bit = si->max; | |
314 | si->highest_bit = 0; | |
1da177e4 | 315 | } |
355cfa73 KH |
316 | if (cache == SWAP_CACHE) /* at usual swap-out via vmscan.c */ |
317 | si->swap_map[offset] = encode_swapmap(0, true); | |
318 | else /* at suspend */ | |
319 | si->swap_map[offset] = encode_swapmap(1, false); | |
ebebbbe9 HD |
320 | si->cluster_next = offset + 1; |
321 | si->flags -= SWP_SCANNING; | |
7992fde7 HD |
322 | |
323 | if (si->lowest_alloc) { | |
324 | /* | |
325 | * Only set when SWP_DISCARDABLE, and there's a scan | |
326 | * for a free cluster in progress or just completed. | |
327 | */ | |
328 | if (found_free_cluster) { | |
329 | /* | |
330 | * To optimize wear-levelling, discard the | |
331 | * old data of the cluster, taking care not to | |
332 | * discard any of its pages that have already | |
333 | * been allocated by racing tasks (offset has | |
334 | * already stepped over any at the beginning). | |
335 | */ | |
336 | if (offset < si->highest_alloc && | |
337 | si->lowest_alloc <= last_in_cluster) | |
338 | last_in_cluster = si->lowest_alloc - 1; | |
339 | si->flags |= SWP_DISCARDING; | |
340 | spin_unlock(&swap_lock); | |
341 | ||
342 | if (offset < last_in_cluster) | |
343 | discard_swap_cluster(si, offset, | |
344 | last_in_cluster - offset + 1); | |
345 | ||
346 | spin_lock(&swap_lock); | |
347 | si->lowest_alloc = 0; | |
348 | si->flags &= ~SWP_DISCARDING; | |
349 | ||
350 | smp_mb(); /* wake_up_bit advises this */ | |
351 | wake_up_bit(&si->flags, ilog2(SWP_DISCARDING)); | |
352 | ||
353 | } else if (si->flags & SWP_DISCARDING) { | |
354 | /* | |
355 | * Delay using pages allocated by racing tasks | |
356 | * until the whole discard has been issued. We | |
357 | * could defer that delay until swap_writepage, | |
358 | * but it's easier to keep this self-contained. | |
359 | */ | |
360 | spin_unlock(&swap_lock); | |
361 | wait_on_bit(&si->flags, ilog2(SWP_DISCARDING), | |
362 | wait_for_discard, TASK_UNINTERRUPTIBLE); | |
363 | spin_lock(&swap_lock); | |
364 | } else { | |
365 | /* | |
366 | * Note pages allocated by racing tasks while | |
367 | * scan for a free cluster is in progress, so | |
368 | * that its final discard can exclude them. | |
369 | */ | |
370 | if (offset < si->lowest_alloc) | |
371 | si->lowest_alloc = offset; | |
372 | if (offset > si->highest_alloc) | |
373 | si->highest_alloc = offset; | |
374 | } | |
375 | } | |
ebebbbe9 | 376 | return offset; |
7dfad418 | 377 | |
ebebbbe9 | 378 | scan: |
5d337b91 | 379 | spin_unlock(&swap_lock); |
7dfad418 | 380 | while (++offset <= si->highest_bit) { |
52b7efdb | 381 | if (!si->swap_map[offset]) { |
5d337b91 | 382 | spin_lock(&swap_lock); |
52b7efdb HD |
383 | goto checks; |
384 | } | |
048c27fd HD |
385 | if (unlikely(--latency_ration < 0)) { |
386 | cond_resched(); | |
387 | latency_ration = LATENCY_LIMIT; | |
388 | } | |
7dfad418 | 389 | } |
c60aa176 HD |
390 | offset = si->lowest_bit; |
391 | while (++offset < scan_base) { | |
392 | if (!si->swap_map[offset]) { | |
393 | spin_lock(&swap_lock); | |
394 | goto checks; | |
395 | } | |
396 | if (unlikely(--latency_ration < 0)) { | |
397 | cond_resched(); | |
398 | latency_ration = LATENCY_LIMIT; | |
399 | } | |
400 | } | |
5d337b91 | 401 | spin_lock(&swap_lock); |
7dfad418 HD |
402 | |
403 | no_page: | |
52b7efdb | 404 | si->flags -= SWP_SCANNING; |
1da177e4 LT |
405 | return 0; |
406 | } | |
407 | ||
408 | swp_entry_t get_swap_page(void) | |
409 | { | |
fb4f88dc HD |
410 | struct swap_info_struct *si; |
411 | pgoff_t offset; | |
412 | int type, next; | |
413 | int wrapped = 0; | |
1da177e4 | 414 | |
5d337b91 | 415 | spin_lock(&swap_lock); |
1da177e4 | 416 | if (nr_swap_pages <= 0) |
fb4f88dc HD |
417 | goto noswap; |
418 | nr_swap_pages--; | |
419 | ||
420 | for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) { | |
421 | si = swap_info + type; | |
422 | next = si->next; | |
423 | if (next < 0 || | |
424 | (!wrapped && si->prio != swap_info[next].prio)) { | |
425 | next = swap_list.head; | |
426 | wrapped++; | |
1da177e4 | 427 | } |
fb4f88dc HD |
428 | |
429 | if (!si->highest_bit) | |
430 | continue; | |
431 | if (!(si->flags & SWP_WRITEOK)) | |
432 | continue; | |
433 | ||
434 | swap_list.next = next; | |
355cfa73 KH |
435 | /* This is called for allocating swap entry for cache */ |
436 | offset = scan_swap_map(si, SWAP_CACHE); | |
5d337b91 HD |
437 | if (offset) { |
438 | spin_unlock(&swap_lock); | |
fb4f88dc | 439 | return swp_entry(type, offset); |
5d337b91 | 440 | } |
fb4f88dc | 441 | next = swap_list.next; |
1da177e4 | 442 | } |
fb4f88dc HD |
443 | |
444 | nr_swap_pages++; | |
445 | noswap: | |
5d337b91 | 446 | spin_unlock(&swap_lock); |
fb4f88dc | 447 | return (swp_entry_t) {0}; |
1da177e4 LT |
448 | } |
449 | ||
355cfa73 | 450 | /* The only caller of this function is now susupend routine */ |
3a291a20 RW |
451 | swp_entry_t get_swap_page_of_type(int type) |
452 | { | |
453 | struct swap_info_struct *si; | |
454 | pgoff_t offset; | |
455 | ||
456 | spin_lock(&swap_lock); | |
457 | si = swap_info + type; | |
458 | if (si->flags & SWP_WRITEOK) { | |
459 | nr_swap_pages--; | |
355cfa73 KH |
460 | /* This is called for allocating swap entry, not cache */ |
461 | offset = scan_swap_map(si, SWAP_MAP); | |
3a291a20 RW |
462 | if (offset) { |
463 | spin_unlock(&swap_lock); | |
464 | return swp_entry(type, offset); | |
465 | } | |
466 | nr_swap_pages++; | |
467 | } | |
468 | spin_unlock(&swap_lock); | |
469 | return (swp_entry_t) {0}; | |
470 | } | |
471 | ||
1da177e4 LT |
472 | static struct swap_info_struct * swap_info_get(swp_entry_t entry) |
473 | { | |
474 | struct swap_info_struct * p; | |
475 | unsigned long offset, type; | |
476 | ||
477 | if (!entry.val) | |
478 | goto out; | |
479 | type = swp_type(entry); | |
480 | if (type >= nr_swapfiles) | |
481 | goto bad_nofile; | |
482 | p = & swap_info[type]; | |
483 | if (!(p->flags & SWP_USED)) | |
484 | goto bad_device; | |
485 | offset = swp_offset(entry); | |
486 | if (offset >= p->max) | |
487 | goto bad_offset; | |
488 | if (!p->swap_map[offset]) | |
489 | goto bad_free; | |
5d337b91 | 490 | spin_lock(&swap_lock); |
1da177e4 LT |
491 | return p; |
492 | ||
493 | bad_free: | |
494 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val); | |
495 | goto out; | |
496 | bad_offset: | |
497 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val); | |
498 | goto out; | |
499 | bad_device: | |
500 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val); | |
501 | goto out; | |
502 | bad_nofile: | |
503 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val); | |
504 | out: | |
505 | return NULL; | |
886bb7e9 | 506 | } |
1da177e4 | 507 | |
355cfa73 KH |
508 | static int swap_entry_free(struct swap_info_struct *p, |
509 | swp_entry_t ent, int cache) | |
1da177e4 | 510 | { |
8c7c6e34 | 511 | unsigned long offset = swp_offset(ent); |
355cfa73 KH |
512 | int count = swap_count(p->swap_map[offset]); |
513 | bool has_cache; | |
514 | ||
515 | has_cache = swap_has_cache(p->swap_map[offset]); | |
516 | ||
517 | if (cache == SWAP_MAP) { /* dropping usage count of swap */ | |
518 | if (count < SWAP_MAP_MAX) { | |
519 | count--; | |
520 | p->swap_map[offset] = encode_swapmap(count, has_cache); | |
1da177e4 | 521 | } |
355cfa73 KH |
522 | } else { /* dropping swap cache flag */ |
523 | VM_BUG_ON(!has_cache); | |
524 | p->swap_map[offset] = encode_swapmap(count, false); | |
525 | ||
526 | } | |
527 | /* return code. */ | |
528 | count = p->swap_map[offset]; | |
529 | /* free if no reference */ | |
530 | if (!count) { | |
531 | if (offset < p->lowest_bit) | |
532 | p->lowest_bit = offset; | |
533 | if (offset > p->highest_bit) | |
534 | p->highest_bit = offset; | |
535 | if (p->prio > swap_info[swap_list.next].prio) | |
536 | swap_list.next = p - swap_info; | |
537 | nr_swap_pages++; | |
538 | p->inuse_pages--; | |
539 | mem_cgroup_uncharge_swap(ent); | |
1da177e4 LT |
540 | } |
541 | return count; | |
542 | } | |
543 | ||
544 | /* | |
545 | * Caller has made sure that the swapdevice corresponding to entry | |
546 | * is still around or has not been recycled. | |
547 | */ | |
548 | void swap_free(swp_entry_t entry) | |
549 | { | |
550 | struct swap_info_struct * p; | |
551 | ||
552 | p = swap_info_get(entry); | |
553 | if (p) { | |
355cfa73 | 554 | swap_entry_free(p, entry, SWAP_MAP); |
5d337b91 | 555 | spin_unlock(&swap_lock); |
1da177e4 LT |
556 | } |
557 | } | |
558 | ||
cb4b86ba KH |
559 | /* |
560 | * Called after dropping swapcache to decrease refcnt to swap entries. | |
561 | */ | |
562 | void swapcache_free(swp_entry_t entry, struct page *page) | |
563 | { | |
355cfa73 KH |
564 | struct swap_info_struct *p; |
565 | ||
cb4b86ba KH |
566 | if (page) |
567 | mem_cgroup_uncharge_swapcache(page, entry); | |
355cfa73 KH |
568 | p = swap_info_get(entry); |
569 | if (p) { | |
570 | swap_entry_free(p, entry, SWAP_CACHE); | |
571 | spin_unlock(&swap_lock); | |
572 | } | |
573 | return; | |
cb4b86ba KH |
574 | } |
575 | ||
1da177e4 | 576 | /* |
c475a8ab | 577 | * How many references to page are currently swapped out? |
1da177e4 | 578 | */ |
c475a8ab | 579 | static inline int page_swapcount(struct page *page) |
1da177e4 | 580 | { |
c475a8ab HD |
581 | int count = 0; |
582 | struct swap_info_struct *p; | |
1da177e4 LT |
583 | swp_entry_t entry; |
584 | ||
4c21e2f2 | 585 | entry.val = page_private(page); |
1da177e4 LT |
586 | p = swap_info_get(entry); |
587 | if (p) { | |
355cfa73 | 588 | count = swap_count(p->swap_map[swp_offset(entry)]); |
5d337b91 | 589 | spin_unlock(&swap_lock); |
1da177e4 | 590 | } |
c475a8ab | 591 | return count; |
1da177e4 LT |
592 | } |
593 | ||
594 | /* | |
7b1fe597 HD |
595 | * We can write to an anon page without COW if there are no other references |
596 | * to it. And as a side-effect, free up its swap: because the old content | |
597 | * on disk will never be read, and seeking back there to write new content | |
598 | * later would only waste time away from clustering. | |
1da177e4 | 599 | */ |
7b1fe597 | 600 | int reuse_swap_page(struct page *page) |
1da177e4 | 601 | { |
c475a8ab HD |
602 | int count; |
603 | ||
51726b12 | 604 | VM_BUG_ON(!PageLocked(page)); |
c475a8ab | 605 | count = page_mapcount(page); |
7b1fe597 | 606 | if (count <= 1 && PageSwapCache(page)) { |
c475a8ab | 607 | count += page_swapcount(page); |
7b1fe597 HD |
608 | if (count == 1 && !PageWriteback(page)) { |
609 | delete_from_swap_cache(page); | |
610 | SetPageDirty(page); | |
611 | } | |
612 | } | |
c475a8ab | 613 | return count == 1; |
1da177e4 LT |
614 | } |
615 | ||
616 | /* | |
a2c43eed HD |
617 | * If swap is getting full, or if there are no more mappings of this page, |
618 | * then try_to_free_swap is called to free its swap space. | |
1da177e4 | 619 | */ |
a2c43eed | 620 | int try_to_free_swap(struct page *page) |
1da177e4 | 621 | { |
51726b12 | 622 | VM_BUG_ON(!PageLocked(page)); |
1da177e4 LT |
623 | |
624 | if (!PageSwapCache(page)) | |
625 | return 0; | |
626 | if (PageWriteback(page)) | |
627 | return 0; | |
a2c43eed | 628 | if (page_swapcount(page)) |
1da177e4 LT |
629 | return 0; |
630 | ||
a2c43eed HD |
631 | delete_from_swap_cache(page); |
632 | SetPageDirty(page); | |
633 | return 1; | |
68a22394 RR |
634 | } |
635 | ||
1da177e4 LT |
636 | /* |
637 | * Free the swap entry like above, but also try to | |
638 | * free the page cache entry if it is the last user. | |
639 | */ | |
2509ef26 | 640 | int free_swap_and_cache(swp_entry_t entry) |
1da177e4 | 641 | { |
2509ef26 | 642 | struct swap_info_struct *p; |
1da177e4 LT |
643 | struct page *page = NULL; |
644 | ||
0697212a | 645 | if (is_migration_entry(entry)) |
2509ef26 | 646 | return 1; |
0697212a | 647 | |
1da177e4 LT |
648 | p = swap_info_get(entry); |
649 | if (p) { | |
355cfa73 | 650 | if (swap_entry_free(p, entry, SWAP_MAP) == SWAP_HAS_CACHE) { |
93fac704 | 651 | page = find_get_page(&swapper_space, entry.val); |
8413ac9d | 652 | if (page && !trylock_page(page)) { |
93fac704 NP |
653 | page_cache_release(page); |
654 | page = NULL; | |
655 | } | |
656 | } | |
5d337b91 | 657 | spin_unlock(&swap_lock); |
1da177e4 LT |
658 | } |
659 | if (page) { | |
a2c43eed HD |
660 | /* |
661 | * Not mapped elsewhere, or swap space full? Free it! | |
662 | * Also recheck PageSwapCache now page is locked (above). | |
663 | */ | |
93fac704 | 664 | if (PageSwapCache(page) && !PageWriteback(page) && |
a2c43eed | 665 | (!page_mapped(page) || vm_swap_full())) { |
1da177e4 LT |
666 | delete_from_swap_cache(page); |
667 | SetPageDirty(page); | |
668 | } | |
669 | unlock_page(page); | |
670 | page_cache_release(page); | |
671 | } | |
2509ef26 | 672 | return p != NULL; |
1da177e4 LT |
673 | } |
674 | ||
b0cb1a19 | 675 | #ifdef CONFIG_HIBERNATION |
f577eb30 | 676 | /* |
915bae9e | 677 | * Find the swap type that corresponds to given device (if any). |
f577eb30 | 678 | * |
915bae9e RW |
679 | * @offset - number of the PAGE_SIZE-sized block of the device, starting |
680 | * from 0, in which the swap header is expected to be located. | |
681 | * | |
682 | * This is needed for the suspend to disk (aka swsusp). | |
f577eb30 | 683 | */ |
7bf23687 | 684 | int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) |
f577eb30 | 685 | { |
915bae9e | 686 | struct block_device *bdev = NULL; |
f577eb30 RW |
687 | int i; |
688 | ||
915bae9e RW |
689 | if (device) |
690 | bdev = bdget(device); | |
691 | ||
f577eb30 RW |
692 | spin_lock(&swap_lock); |
693 | for (i = 0; i < nr_swapfiles; i++) { | |
915bae9e | 694 | struct swap_info_struct *sis = swap_info + i; |
f577eb30 | 695 | |
915bae9e | 696 | if (!(sis->flags & SWP_WRITEOK)) |
f577eb30 | 697 | continue; |
b6b5bce3 | 698 | |
915bae9e | 699 | if (!bdev) { |
7bf23687 | 700 | if (bdev_p) |
a1bb7d61 | 701 | *bdev_p = bdget(sis->bdev->bd_dev); |
7bf23687 | 702 | |
6e1819d6 RW |
703 | spin_unlock(&swap_lock); |
704 | return i; | |
705 | } | |
915bae9e RW |
706 | if (bdev == sis->bdev) { |
707 | struct swap_extent *se; | |
708 | ||
709 | se = list_entry(sis->extent_list.next, | |
710 | struct swap_extent, list); | |
711 | if (se->start_block == offset) { | |
7bf23687 | 712 | if (bdev_p) |
a1bb7d61 | 713 | *bdev_p = bdget(sis->bdev->bd_dev); |
7bf23687 | 714 | |
915bae9e RW |
715 | spin_unlock(&swap_lock); |
716 | bdput(bdev); | |
717 | return i; | |
718 | } | |
f577eb30 RW |
719 | } |
720 | } | |
721 | spin_unlock(&swap_lock); | |
915bae9e RW |
722 | if (bdev) |
723 | bdput(bdev); | |
724 | ||
f577eb30 RW |
725 | return -ENODEV; |
726 | } | |
727 | ||
728 | /* | |
729 | * Return either the total number of swap pages of given type, or the number | |
730 | * of free pages of that type (depending on @free) | |
731 | * | |
732 | * This is needed for software suspend | |
733 | */ | |
734 | unsigned int count_swap_pages(int type, int free) | |
735 | { | |
736 | unsigned int n = 0; | |
737 | ||
738 | if (type < nr_swapfiles) { | |
739 | spin_lock(&swap_lock); | |
740 | if (swap_info[type].flags & SWP_WRITEOK) { | |
741 | n = swap_info[type].pages; | |
742 | if (free) | |
743 | n -= swap_info[type].inuse_pages; | |
744 | } | |
745 | spin_unlock(&swap_lock); | |
746 | } | |
747 | return n; | |
748 | } | |
749 | #endif | |
750 | ||
1da177e4 | 751 | /* |
72866f6f HD |
752 | * No need to decide whether this PTE shares the swap entry with others, |
753 | * just let do_wp_page work it out if a write is requested later - to | |
754 | * force COW, vm_page_prot omits write permission from any private vma. | |
1da177e4 | 755 | */ |
044d66c1 | 756 | static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
1da177e4 LT |
757 | unsigned long addr, swp_entry_t entry, struct page *page) |
758 | { | |
7a81b88c | 759 | struct mem_cgroup *ptr = NULL; |
044d66c1 HD |
760 | spinlock_t *ptl; |
761 | pte_t *pte; | |
762 | int ret = 1; | |
763 | ||
85d9fc89 | 764 | if (mem_cgroup_try_charge_swapin(vma->vm_mm, page, GFP_KERNEL, &ptr)) { |
044d66c1 | 765 | ret = -ENOMEM; |
85d9fc89 KH |
766 | goto out_nolock; |
767 | } | |
044d66c1 HD |
768 | |
769 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); | |
770 | if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) { | |
771 | if (ret > 0) | |
7a81b88c | 772 | mem_cgroup_cancel_charge_swapin(ptr); |
044d66c1 HD |
773 | ret = 0; |
774 | goto out; | |
775 | } | |
8a9f3ccd | 776 | |
4294621f | 777 | inc_mm_counter(vma->vm_mm, anon_rss); |
1da177e4 LT |
778 | get_page(page); |
779 | set_pte_at(vma->vm_mm, addr, pte, | |
780 | pte_mkold(mk_pte(page, vma->vm_page_prot))); | |
781 | page_add_anon_rmap(page, vma, addr); | |
7a81b88c | 782 | mem_cgroup_commit_charge_swapin(page, ptr); |
1da177e4 LT |
783 | swap_free(entry); |
784 | /* | |
785 | * Move the page to the active list so it is not | |
786 | * immediately swapped out again after swapon. | |
787 | */ | |
788 | activate_page(page); | |
044d66c1 HD |
789 | out: |
790 | pte_unmap_unlock(pte, ptl); | |
85d9fc89 | 791 | out_nolock: |
044d66c1 | 792 | return ret; |
1da177e4 LT |
793 | } |
794 | ||
795 | static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, | |
796 | unsigned long addr, unsigned long end, | |
797 | swp_entry_t entry, struct page *page) | |
798 | { | |
1da177e4 | 799 | pte_t swp_pte = swp_entry_to_pte(entry); |
705e87c0 | 800 | pte_t *pte; |
8a9f3ccd | 801 | int ret = 0; |
1da177e4 | 802 | |
044d66c1 HD |
803 | /* |
804 | * We don't actually need pte lock while scanning for swp_pte: since | |
805 | * we hold page lock and mmap_sem, swp_pte cannot be inserted into the | |
806 | * page table while we're scanning; though it could get zapped, and on | |
807 | * some architectures (e.g. x86_32 with PAE) we might catch a glimpse | |
808 | * of unmatched parts which look like swp_pte, so unuse_pte must | |
809 | * recheck under pte lock. Scanning without pte lock lets it be | |
810 | * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE. | |
811 | */ | |
812 | pte = pte_offset_map(pmd, addr); | |
1da177e4 LT |
813 | do { |
814 | /* | |
815 | * swapoff spends a _lot_ of time in this loop! | |
816 | * Test inline before going to call unuse_pte. | |
817 | */ | |
818 | if (unlikely(pte_same(*pte, swp_pte))) { | |
044d66c1 HD |
819 | pte_unmap(pte); |
820 | ret = unuse_pte(vma, pmd, addr, entry, page); | |
821 | if (ret) | |
822 | goto out; | |
823 | pte = pte_offset_map(pmd, addr); | |
1da177e4 LT |
824 | } |
825 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
044d66c1 HD |
826 | pte_unmap(pte - 1); |
827 | out: | |
8a9f3ccd | 828 | return ret; |
1da177e4 LT |
829 | } |
830 | ||
831 | static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, | |
832 | unsigned long addr, unsigned long end, | |
833 | swp_entry_t entry, struct page *page) | |
834 | { | |
835 | pmd_t *pmd; | |
836 | unsigned long next; | |
8a9f3ccd | 837 | int ret; |
1da177e4 LT |
838 | |
839 | pmd = pmd_offset(pud, addr); | |
840 | do { | |
841 | next = pmd_addr_end(addr, end); | |
842 | if (pmd_none_or_clear_bad(pmd)) | |
843 | continue; | |
8a9f3ccd BS |
844 | ret = unuse_pte_range(vma, pmd, addr, next, entry, page); |
845 | if (ret) | |
846 | return ret; | |
1da177e4 LT |
847 | } while (pmd++, addr = next, addr != end); |
848 | return 0; | |
849 | } | |
850 | ||
851 | static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd, | |
852 | unsigned long addr, unsigned long end, | |
853 | swp_entry_t entry, struct page *page) | |
854 | { | |
855 | pud_t *pud; | |
856 | unsigned long next; | |
8a9f3ccd | 857 | int ret; |
1da177e4 LT |
858 | |
859 | pud = pud_offset(pgd, addr); | |
860 | do { | |
861 | next = pud_addr_end(addr, end); | |
862 | if (pud_none_or_clear_bad(pud)) | |
863 | continue; | |
8a9f3ccd BS |
864 | ret = unuse_pmd_range(vma, pud, addr, next, entry, page); |
865 | if (ret) | |
866 | return ret; | |
1da177e4 LT |
867 | } while (pud++, addr = next, addr != end); |
868 | return 0; | |
869 | } | |
870 | ||
871 | static int unuse_vma(struct vm_area_struct *vma, | |
872 | swp_entry_t entry, struct page *page) | |
873 | { | |
874 | pgd_t *pgd; | |
875 | unsigned long addr, end, next; | |
8a9f3ccd | 876 | int ret; |
1da177e4 LT |
877 | |
878 | if (page->mapping) { | |
879 | addr = page_address_in_vma(page, vma); | |
880 | if (addr == -EFAULT) | |
881 | return 0; | |
882 | else | |
883 | end = addr + PAGE_SIZE; | |
884 | } else { | |
885 | addr = vma->vm_start; | |
886 | end = vma->vm_end; | |
887 | } | |
888 | ||
889 | pgd = pgd_offset(vma->vm_mm, addr); | |
890 | do { | |
891 | next = pgd_addr_end(addr, end); | |
892 | if (pgd_none_or_clear_bad(pgd)) | |
893 | continue; | |
8a9f3ccd BS |
894 | ret = unuse_pud_range(vma, pgd, addr, next, entry, page); |
895 | if (ret) | |
896 | return ret; | |
1da177e4 LT |
897 | } while (pgd++, addr = next, addr != end); |
898 | return 0; | |
899 | } | |
900 | ||
901 | static int unuse_mm(struct mm_struct *mm, | |
902 | swp_entry_t entry, struct page *page) | |
903 | { | |
904 | struct vm_area_struct *vma; | |
8a9f3ccd | 905 | int ret = 0; |
1da177e4 LT |
906 | |
907 | if (!down_read_trylock(&mm->mmap_sem)) { | |
908 | /* | |
7d03431c FLVC |
909 | * Activate page so shrink_inactive_list is unlikely to unmap |
910 | * its ptes while lock is dropped, so swapoff can make progress. | |
1da177e4 | 911 | */ |
c475a8ab | 912 | activate_page(page); |
1da177e4 LT |
913 | unlock_page(page); |
914 | down_read(&mm->mmap_sem); | |
915 | lock_page(page); | |
916 | } | |
1da177e4 | 917 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
8a9f3ccd | 918 | if (vma->anon_vma && (ret = unuse_vma(vma, entry, page))) |
1da177e4 LT |
919 | break; |
920 | } | |
1da177e4 | 921 | up_read(&mm->mmap_sem); |
8a9f3ccd | 922 | return (ret < 0)? ret: 0; |
1da177e4 LT |
923 | } |
924 | ||
925 | /* | |
926 | * Scan swap_map from current position to next entry still in use. | |
927 | * Recycle to start on reaching the end, returning 0 when empty. | |
928 | */ | |
6eb396dc HD |
929 | static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
930 | unsigned int prev) | |
1da177e4 | 931 | { |
6eb396dc HD |
932 | unsigned int max = si->max; |
933 | unsigned int i = prev; | |
1da177e4 LT |
934 | int count; |
935 | ||
936 | /* | |
5d337b91 | 937 | * No need for swap_lock here: we're just looking |
1da177e4 LT |
938 | * for whether an entry is in use, not modifying it; false |
939 | * hits are okay, and sys_swapoff() has already prevented new | |
5d337b91 | 940 | * allocations from this area (while holding swap_lock). |
1da177e4 LT |
941 | */ |
942 | for (;;) { | |
943 | if (++i >= max) { | |
944 | if (!prev) { | |
945 | i = 0; | |
946 | break; | |
947 | } | |
948 | /* | |
949 | * No entries in use at top of swap_map, | |
950 | * loop back to start and recheck there. | |
951 | */ | |
952 | max = prev + 1; | |
953 | prev = 0; | |
954 | i = 1; | |
955 | } | |
956 | count = si->swap_map[i]; | |
355cfa73 | 957 | if (count && swap_count(count) != SWAP_MAP_BAD) |
1da177e4 LT |
958 | break; |
959 | } | |
960 | return i; | |
961 | } | |
962 | ||
963 | /* | |
964 | * We completely avoid races by reading each swap page in advance, | |
965 | * and then search for the process using it. All the necessary | |
966 | * page table adjustments can then be made atomically. | |
967 | */ | |
968 | static int try_to_unuse(unsigned int type) | |
969 | { | |
970 | struct swap_info_struct * si = &swap_info[type]; | |
971 | struct mm_struct *start_mm; | |
972 | unsigned short *swap_map; | |
973 | unsigned short swcount; | |
974 | struct page *page; | |
975 | swp_entry_t entry; | |
6eb396dc | 976 | unsigned int i = 0; |
1da177e4 LT |
977 | int retval = 0; |
978 | int reset_overflow = 0; | |
979 | int shmem; | |
980 | ||
981 | /* | |
982 | * When searching mms for an entry, a good strategy is to | |
983 | * start at the first mm we freed the previous entry from | |
984 | * (though actually we don't notice whether we or coincidence | |
985 | * freed the entry). Initialize this start_mm with a hold. | |
986 | * | |
987 | * A simpler strategy would be to start at the last mm we | |
988 | * freed the previous entry from; but that would take less | |
989 | * advantage of mmlist ordering, which clusters forked mms | |
990 | * together, child after parent. If we race with dup_mmap(), we | |
991 | * prefer to resolve parent before child, lest we miss entries | |
992 | * duplicated after we scanned child: using last mm would invert | |
993 | * that. Though it's only a serious concern when an overflowed | |
994 | * swap count is reset from SWAP_MAP_MAX, preventing a rescan. | |
995 | */ | |
996 | start_mm = &init_mm; | |
997 | atomic_inc(&init_mm.mm_users); | |
998 | ||
999 | /* | |
1000 | * Keep on scanning until all entries have gone. Usually, | |
1001 | * one pass through swap_map is enough, but not necessarily: | |
1002 | * there are races when an instance of an entry might be missed. | |
1003 | */ | |
1004 | while ((i = find_next_to_unuse(si, i)) != 0) { | |
1005 | if (signal_pending(current)) { | |
1006 | retval = -EINTR; | |
1007 | break; | |
1008 | } | |
1009 | ||
886bb7e9 | 1010 | /* |
1da177e4 LT |
1011 | * Get a page for the entry, using the existing swap |
1012 | * cache page if there is one. Otherwise, get a clean | |
886bb7e9 | 1013 | * page and read the swap into it. |
1da177e4 LT |
1014 | */ |
1015 | swap_map = &si->swap_map[i]; | |
1016 | entry = swp_entry(type, i); | |
02098fea HD |
1017 | page = read_swap_cache_async(entry, |
1018 | GFP_HIGHUSER_MOVABLE, NULL, 0); | |
1da177e4 LT |
1019 | if (!page) { |
1020 | /* | |
1021 | * Either swap_duplicate() failed because entry | |
1022 | * has been freed independently, and will not be | |
1023 | * reused since sys_swapoff() already disabled | |
1024 | * allocation from here, or alloc_page() failed. | |
1025 | */ | |
1026 | if (!*swap_map) | |
1027 | continue; | |
1028 | retval = -ENOMEM; | |
1029 | break; | |
1030 | } | |
1031 | ||
1032 | /* | |
1033 | * Don't hold on to start_mm if it looks like exiting. | |
1034 | */ | |
1035 | if (atomic_read(&start_mm->mm_users) == 1) { | |
1036 | mmput(start_mm); | |
1037 | start_mm = &init_mm; | |
1038 | atomic_inc(&init_mm.mm_users); | |
1039 | } | |
1040 | ||
1041 | /* | |
1042 | * Wait for and lock page. When do_swap_page races with | |
1043 | * try_to_unuse, do_swap_page can handle the fault much | |
1044 | * faster than try_to_unuse can locate the entry. This | |
1045 | * apparently redundant "wait_on_page_locked" lets try_to_unuse | |
1046 | * defer to do_swap_page in such a case - in some tests, | |
1047 | * do_swap_page and try_to_unuse repeatedly compete. | |
1048 | */ | |
1049 | wait_on_page_locked(page); | |
1050 | wait_on_page_writeback(page); | |
1051 | lock_page(page); | |
1052 | wait_on_page_writeback(page); | |
1053 | ||
1054 | /* | |
1055 | * Remove all references to entry. | |
1056 | * Whenever we reach init_mm, there's no address space | |
1057 | * to search, but use it as a reminder to search shmem. | |
1058 | */ | |
1059 | shmem = 0; | |
1060 | swcount = *swap_map; | |
355cfa73 | 1061 | if (swap_count(swcount)) { |
1da177e4 LT |
1062 | if (start_mm == &init_mm) |
1063 | shmem = shmem_unuse(entry, page); | |
1064 | else | |
1065 | retval = unuse_mm(start_mm, entry, page); | |
1066 | } | |
355cfa73 | 1067 | if (swap_count(*swap_map)) { |
1da177e4 LT |
1068 | int set_start_mm = (*swap_map >= swcount); |
1069 | struct list_head *p = &start_mm->mmlist; | |
1070 | struct mm_struct *new_start_mm = start_mm; | |
1071 | struct mm_struct *prev_mm = start_mm; | |
1072 | struct mm_struct *mm; | |
1073 | ||
1074 | atomic_inc(&new_start_mm->mm_users); | |
1075 | atomic_inc(&prev_mm->mm_users); | |
1076 | spin_lock(&mmlist_lock); | |
355cfa73 | 1077 | while (swap_count(*swap_map) && !retval && !shmem && |
1da177e4 LT |
1078 | (p = p->next) != &start_mm->mmlist) { |
1079 | mm = list_entry(p, struct mm_struct, mmlist); | |
70af7c5c | 1080 | if (!atomic_inc_not_zero(&mm->mm_users)) |
1da177e4 | 1081 | continue; |
1da177e4 LT |
1082 | spin_unlock(&mmlist_lock); |
1083 | mmput(prev_mm); | |
1084 | prev_mm = mm; | |
1085 | ||
1086 | cond_resched(); | |
1087 | ||
1088 | swcount = *swap_map; | |
355cfa73 | 1089 | if (!swap_count(swcount)) /* any usage ? */ |
1da177e4 LT |
1090 | ; |
1091 | else if (mm == &init_mm) { | |
1092 | set_start_mm = 1; | |
1093 | shmem = shmem_unuse(entry, page); | |
1094 | } else | |
1095 | retval = unuse_mm(mm, entry, page); | |
355cfa73 KH |
1096 | |
1097 | if (set_start_mm && | |
1098 | swap_count(*swap_map) < swcount) { | |
1da177e4 LT |
1099 | mmput(new_start_mm); |
1100 | atomic_inc(&mm->mm_users); | |
1101 | new_start_mm = mm; | |
1102 | set_start_mm = 0; | |
1103 | } | |
1104 | spin_lock(&mmlist_lock); | |
1105 | } | |
1106 | spin_unlock(&mmlist_lock); | |
1107 | mmput(prev_mm); | |
1108 | mmput(start_mm); | |
1109 | start_mm = new_start_mm; | |
1110 | } | |
2e0e26c7 HD |
1111 | if (shmem) { |
1112 | /* page has already been unlocked and released */ | |
1113 | if (shmem > 0) | |
1114 | continue; | |
1115 | retval = shmem; | |
1116 | break; | |
1117 | } | |
1da177e4 LT |
1118 | if (retval) { |
1119 | unlock_page(page); | |
1120 | page_cache_release(page); | |
1121 | break; | |
1122 | } | |
1123 | ||
1124 | /* | |
355cfa73 KH |
1125 | * How could swap count reach 0x7ffe ? |
1126 | * There's no way to repeat a swap page within an mm | |
1127 | * (except in shmem, where it's the shared object which takes | |
1128 | * the reference count)? | |
1129 | * We believe SWAP_MAP_MAX cannot occur.(if occur, unsigned | |
1130 | * short is too small....) | |
1da177e4 LT |
1131 | * If that's wrong, then we should worry more about |
1132 | * exit_mmap() and do_munmap() cases described above: | |
1133 | * we might be resetting SWAP_MAP_MAX too early here. | |
1134 | * We know "Undead"s can happen, they're okay, so don't | |
1135 | * report them; but do report if we reset SWAP_MAP_MAX. | |
1136 | */ | |
355cfa73 KH |
1137 | /* We might release the lock_page() in unuse_mm(). */ |
1138 | if (!PageSwapCache(page) || page_private(page) != entry.val) | |
1139 | goto retry; | |
1140 | ||
1141 | if (swap_count(*swap_map) == SWAP_MAP_MAX) { | |
5d337b91 | 1142 | spin_lock(&swap_lock); |
355cfa73 | 1143 | *swap_map = encode_swapmap(0, true); |
5d337b91 | 1144 | spin_unlock(&swap_lock); |
1da177e4 LT |
1145 | reset_overflow = 1; |
1146 | } | |
1147 | ||
1148 | /* | |
1149 | * If a reference remains (rare), we would like to leave | |
1150 | * the page in the swap cache; but try_to_unmap could | |
1151 | * then re-duplicate the entry once we drop page lock, | |
1152 | * so we might loop indefinitely; also, that page could | |
1153 | * not be swapped out to other storage meanwhile. So: | |
1154 | * delete from cache even if there's another reference, | |
1155 | * after ensuring that the data has been saved to disk - | |
1156 | * since if the reference remains (rarer), it will be | |
1157 | * read from disk into another page. Splitting into two | |
1158 | * pages would be incorrect if swap supported "shared | |
1159 | * private" pages, but they are handled by tmpfs files. | |
1da177e4 | 1160 | */ |
355cfa73 KH |
1161 | if (swap_count(*swap_map) && |
1162 | PageDirty(page) && PageSwapCache(page)) { | |
1da177e4 LT |
1163 | struct writeback_control wbc = { |
1164 | .sync_mode = WB_SYNC_NONE, | |
1165 | }; | |
1166 | ||
1167 | swap_writepage(page, &wbc); | |
1168 | lock_page(page); | |
1169 | wait_on_page_writeback(page); | |
1170 | } | |
68bdc8d6 HD |
1171 | |
1172 | /* | |
1173 | * It is conceivable that a racing task removed this page from | |
1174 | * swap cache just before we acquired the page lock at the top, | |
1175 | * or while we dropped it in unuse_mm(). The page might even | |
1176 | * be back in swap cache on another swap area: that we must not | |
1177 | * delete, since it may not have been written out to swap yet. | |
1178 | */ | |
1179 | if (PageSwapCache(page) && | |
1180 | likely(page_private(page) == entry.val)) | |
2e0e26c7 | 1181 | delete_from_swap_cache(page); |
1da177e4 LT |
1182 | |
1183 | /* | |
1184 | * So we could skip searching mms once swap count went | |
1185 | * to 1, we did not mark any present ptes as dirty: must | |
2706a1b8 | 1186 | * mark page dirty so shrink_page_list will preserve it. |
1da177e4 LT |
1187 | */ |
1188 | SetPageDirty(page); | |
355cfa73 | 1189 | retry: |
1da177e4 LT |
1190 | unlock_page(page); |
1191 | page_cache_release(page); | |
1192 | ||
1193 | /* | |
1194 | * Make sure that we aren't completely killing | |
1195 | * interactive performance. | |
1196 | */ | |
1197 | cond_resched(); | |
1198 | } | |
1199 | ||
1200 | mmput(start_mm); | |
1201 | if (reset_overflow) { | |
1202 | printk(KERN_WARNING "swapoff: cleared swap entry overflow\n"); | |
1203 | swap_overflow = 0; | |
1204 | } | |
1205 | return retval; | |
1206 | } | |
1207 | ||
1208 | /* | |
5d337b91 HD |
1209 | * After a successful try_to_unuse, if no swap is now in use, we know |
1210 | * we can empty the mmlist. swap_lock must be held on entry and exit. | |
1211 | * Note that mmlist_lock nests inside swap_lock, and an mm must be | |
1da177e4 LT |
1212 | * added to the mmlist just after page_duplicate - before would be racy. |
1213 | */ | |
1214 | static void drain_mmlist(void) | |
1215 | { | |
1216 | struct list_head *p, *next; | |
1217 | unsigned int i; | |
1218 | ||
1219 | for (i = 0; i < nr_swapfiles; i++) | |
1220 | if (swap_info[i].inuse_pages) | |
1221 | return; | |
1222 | spin_lock(&mmlist_lock); | |
1223 | list_for_each_safe(p, next, &init_mm.mmlist) | |
1224 | list_del_init(p); | |
1225 | spin_unlock(&mmlist_lock); | |
1226 | } | |
1227 | ||
1228 | /* | |
1229 | * Use this swapdev's extent info to locate the (PAGE_SIZE) block which | |
1230 | * corresponds to page offset `offset'. | |
1231 | */ | |
1232 | sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset) | |
1233 | { | |
1234 | struct swap_extent *se = sis->curr_swap_extent; | |
1235 | struct swap_extent *start_se = se; | |
1236 | ||
1237 | for ( ; ; ) { | |
1238 | struct list_head *lh; | |
1239 | ||
1240 | if (se->start_page <= offset && | |
1241 | offset < (se->start_page + se->nr_pages)) { | |
1242 | return se->start_block + (offset - se->start_page); | |
1243 | } | |
11d31886 | 1244 | lh = se->list.next; |
1da177e4 | 1245 | if (lh == &sis->extent_list) |
11d31886 | 1246 | lh = lh->next; |
1da177e4 LT |
1247 | se = list_entry(lh, struct swap_extent, list); |
1248 | sis->curr_swap_extent = se; | |
1249 | BUG_ON(se == start_se); /* It *must* be present */ | |
1250 | } | |
1251 | } | |
1252 | ||
b0cb1a19 | 1253 | #ifdef CONFIG_HIBERNATION |
3aef83e0 RW |
1254 | /* |
1255 | * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev | |
1256 | * corresponding to given index in swap_info (swap type). | |
1257 | */ | |
1258 | sector_t swapdev_block(int swap_type, pgoff_t offset) | |
1259 | { | |
1260 | struct swap_info_struct *sis; | |
1261 | ||
1262 | if (swap_type >= nr_swapfiles) | |
1263 | return 0; | |
1264 | ||
1265 | sis = swap_info + swap_type; | |
1266 | return (sis->flags & SWP_WRITEOK) ? map_swap_page(sis, offset) : 0; | |
1267 | } | |
b0cb1a19 | 1268 | #endif /* CONFIG_HIBERNATION */ |
3aef83e0 | 1269 | |
1da177e4 LT |
1270 | /* |
1271 | * Free all of a swapdev's extent information | |
1272 | */ | |
1273 | static void destroy_swap_extents(struct swap_info_struct *sis) | |
1274 | { | |
1275 | while (!list_empty(&sis->extent_list)) { | |
1276 | struct swap_extent *se; | |
1277 | ||
1278 | se = list_entry(sis->extent_list.next, | |
1279 | struct swap_extent, list); | |
1280 | list_del(&se->list); | |
1281 | kfree(se); | |
1282 | } | |
1da177e4 LT |
1283 | } |
1284 | ||
1285 | /* | |
1286 | * Add a block range (and the corresponding page range) into this swapdev's | |
11d31886 | 1287 | * extent list. The extent list is kept sorted in page order. |
1da177e4 | 1288 | * |
11d31886 | 1289 | * This function rather assumes that it is called in ascending page order. |
1da177e4 LT |
1290 | */ |
1291 | static int | |
1292 | add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, | |
1293 | unsigned long nr_pages, sector_t start_block) | |
1294 | { | |
1295 | struct swap_extent *se; | |
1296 | struct swap_extent *new_se; | |
1297 | struct list_head *lh; | |
1298 | ||
11d31886 HD |
1299 | lh = sis->extent_list.prev; /* The highest page extent */ |
1300 | if (lh != &sis->extent_list) { | |
1da177e4 | 1301 | se = list_entry(lh, struct swap_extent, list); |
11d31886 HD |
1302 | BUG_ON(se->start_page + se->nr_pages != start_page); |
1303 | if (se->start_block + se->nr_pages == start_block) { | |
1da177e4 LT |
1304 | /* Merge it */ |
1305 | se->nr_pages += nr_pages; | |
1306 | return 0; | |
1307 | } | |
1da177e4 LT |
1308 | } |
1309 | ||
1310 | /* | |
1311 | * No merge. Insert a new extent, preserving ordering. | |
1312 | */ | |
1313 | new_se = kmalloc(sizeof(*se), GFP_KERNEL); | |
1314 | if (new_se == NULL) | |
1315 | return -ENOMEM; | |
1316 | new_se->start_page = start_page; | |
1317 | new_se->nr_pages = nr_pages; | |
1318 | new_se->start_block = start_block; | |
1319 | ||
11d31886 | 1320 | list_add_tail(&new_se->list, &sis->extent_list); |
53092a74 | 1321 | return 1; |
1da177e4 LT |
1322 | } |
1323 | ||
1324 | /* | |
1325 | * A `swap extent' is a simple thing which maps a contiguous range of pages | |
1326 | * onto a contiguous range of disk blocks. An ordered list of swap extents | |
1327 | * is built at swapon time and is then used at swap_writepage/swap_readpage | |
1328 | * time for locating where on disk a page belongs. | |
1329 | * | |
1330 | * If the swapfile is an S_ISBLK block device, a single extent is installed. | |
1331 | * This is done so that the main operating code can treat S_ISBLK and S_ISREG | |
1332 | * swap files identically. | |
1333 | * | |
1334 | * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap | |
1335 | * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK | |
1336 | * swapfiles are handled *identically* after swapon time. | |
1337 | * | |
1338 | * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks | |
1339 | * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If | |
1340 | * some stray blocks are found which do not fall within the PAGE_SIZE alignment | |
1341 | * requirements, they are simply tossed out - we will never use those blocks | |
1342 | * for swapping. | |
1343 | * | |
b0d9bcd4 | 1344 | * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This |
1da177e4 LT |
1345 | * prevents root from shooting her foot off by ftruncating an in-use swapfile, |
1346 | * which will scribble on the fs. | |
1347 | * | |
1348 | * The amount of disk space which a single swap extent represents varies. | |
1349 | * Typically it is in the 1-4 megabyte range. So we can have hundreds of | |
1350 | * extents in the list. To avoid much list walking, we cache the previous | |
1351 | * search location in `curr_swap_extent', and start new searches from there. | |
1352 | * This is extremely effective. The average number of iterations in | |
1353 | * map_swap_page() has been measured at about 0.3 per page. - akpm. | |
1354 | */ | |
53092a74 | 1355 | static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
1da177e4 LT |
1356 | { |
1357 | struct inode *inode; | |
1358 | unsigned blocks_per_page; | |
1359 | unsigned long page_no; | |
1360 | unsigned blkbits; | |
1361 | sector_t probe_block; | |
1362 | sector_t last_block; | |
53092a74 HD |
1363 | sector_t lowest_block = -1; |
1364 | sector_t highest_block = 0; | |
1365 | int nr_extents = 0; | |
1da177e4 LT |
1366 | int ret; |
1367 | ||
1368 | inode = sis->swap_file->f_mapping->host; | |
1369 | if (S_ISBLK(inode->i_mode)) { | |
1370 | ret = add_swap_extent(sis, 0, sis->max, 0); | |
53092a74 | 1371 | *span = sis->pages; |
1da177e4 LT |
1372 | goto done; |
1373 | } | |
1374 | ||
1375 | blkbits = inode->i_blkbits; | |
1376 | blocks_per_page = PAGE_SIZE >> blkbits; | |
1377 | ||
1378 | /* | |
1379 | * Map all the blocks into the extent list. This code doesn't try | |
1380 | * to be very smart. | |
1381 | */ | |
1382 | probe_block = 0; | |
1383 | page_no = 0; | |
1384 | last_block = i_size_read(inode) >> blkbits; | |
1385 | while ((probe_block + blocks_per_page) <= last_block && | |
1386 | page_no < sis->max) { | |
1387 | unsigned block_in_page; | |
1388 | sector_t first_block; | |
1389 | ||
1390 | first_block = bmap(inode, probe_block); | |
1391 | if (first_block == 0) | |
1392 | goto bad_bmap; | |
1393 | ||
1394 | /* | |
1395 | * It must be PAGE_SIZE aligned on-disk | |
1396 | */ | |
1397 | if (first_block & (blocks_per_page - 1)) { | |
1398 | probe_block++; | |
1399 | goto reprobe; | |
1400 | } | |
1401 | ||
1402 | for (block_in_page = 1; block_in_page < blocks_per_page; | |
1403 | block_in_page++) { | |
1404 | sector_t block; | |
1405 | ||
1406 | block = bmap(inode, probe_block + block_in_page); | |
1407 | if (block == 0) | |
1408 | goto bad_bmap; | |
1409 | if (block != first_block + block_in_page) { | |
1410 | /* Discontiguity */ | |
1411 | probe_block++; | |
1412 | goto reprobe; | |
1413 | } | |
1414 | } | |
1415 | ||
53092a74 HD |
1416 | first_block >>= (PAGE_SHIFT - blkbits); |
1417 | if (page_no) { /* exclude the header page */ | |
1418 | if (first_block < lowest_block) | |
1419 | lowest_block = first_block; | |
1420 | if (first_block > highest_block) | |
1421 | highest_block = first_block; | |
1422 | } | |
1423 | ||
1da177e4 LT |
1424 | /* |
1425 | * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks | |
1426 | */ | |
53092a74 HD |
1427 | ret = add_swap_extent(sis, page_no, 1, first_block); |
1428 | if (ret < 0) | |
1da177e4 | 1429 | goto out; |
53092a74 | 1430 | nr_extents += ret; |
1da177e4 LT |
1431 | page_no++; |
1432 | probe_block += blocks_per_page; | |
1433 | reprobe: | |
1434 | continue; | |
1435 | } | |
53092a74 HD |
1436 | ret = nr_extents; |
1437 | *span = 1 + highest_block - lowest_block; | |
1da177e4 | 1438 | if (page_no == 0) |
e2244ec2 | 1439 | page_no = 1; /* force Empty message */ |
1da177e4 | 1440 | sis->max = page_no; |
e2244ec2 | 1441 | sis->pages = page_no - 1; |
1da177e4 LT |
1442 | sis->highest_bit = page_no - 1; |
1443 | done: | |
1444 | sis->curr_swap_extent = list_entry(sis->extent_list.prev, | |
1445 | struct swap_extent, list); | |
1446 | goto out; | |
1447 | bad_bmap: | |
1448 | printk(KERN_ERR "swapon: swapfile has holes\n"); | |
1449 | ret = -EINVAL; | |
1450 | out: | |
1451 | return ret; | |
1452 | } | |
1453 | ||
c4ea37c2 | 1454 | SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) |
1da177e4 LT |
1455 | { |
1456 | struct swap_info_struct * p = NULL; | |
1457 | unsigned short *swap_map; | |
1458 | struct file *swap_file, *victim; | |
1459 | struct address_space *mapping; | |
1460 | struct inode *inode; | |
1461 | char * pathname; | |
1462 | int i, type, prev; | |
1463 | int err; | |
886bb7e9 | 1464 | |
1da177e4 LT |
1465 | if (!capable(CAP_SYS_ADMIN)) |
1466 | return -EPERM; | |
1467 | ||
1468 | pathname = getname(specialfile); | |
1469 | err = PTR_ERR(pathname); | |
1470 | if (IS_ERR(pathname)) | |
1471 | goto out; | |
1472 | ||
1473 | victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0); | |
1474 | putname(pathname); | |
1475 | err = PTR_ERR(victim); | |
1476 | if (IS_ERR(victim)) | |
1477 | goto out; | |
1478 | ||
1479 | mapping = victim->f_mapping; | |
1480 | prev = -1; | |
5d337b91 | 1481 | spin_lock(&swap_lock); |
1da177e4 LT |
1482 | for (type = swap_list.head; type >= 0; type = swap_info[type].next) { |
1483 | p = swap_info + type; | |
22c6f8fd | 1484 | if (p->flags & SWP_WRITEOK) { |
1da177e4 LT |
1485 | if (p->swap_file->f_mapping == mapping) |
1486 | break; | |
1487 | } | |
1488 | prev = type; | |
1489 | } | |
1490 | if (type < 0) { | |
1491 | err = -EINVAL; | |
5d337b91 | 1492 | spin_unlock(&swap_lock); |
1da177e4 LT |
1493 | goto out_dput; |
1494 | } | |
1495 | if (!security_vm_enough_memory(p->pages)) | |
1496 | vm_unacct_memory(p->pages); | |
1497 | else { | |
1498 | err = -ENOMEM; | |
5d337b91 | 1499 | spin_unlock(&swap_lock); |
1da177e4 LT |
1500 | goto out_dput; |
1501 | } | |
1502 | if (prev < 0) { | |
1503 | swap_list.head = p->next; | |
1504 | } else { | |
1505 | swap_info[prev].next = p->next; | |
1506 | } | |
1507 | if (type == swap_list.next) { | |
1508 | /* just pick something that's safe... */ | |
1509 | swap_list.next = swap_list.head; | |
1510 | } | |
78ecba08 HD |
1511 | if (p->prio < 0) { |
1512 | for (i = p->next; i >= 0; i = swap_info[i].next) | |
1513 | swap_info[i].prio = p->prio--; | |
1514 | least_priority++; | |
1515 | } | |
1da177e4 LT |
1516 | nr_swap_pages -= p->pages; |
1517 | total_swap_pages -= p->pages; | |
1518 | p->flags &= ~SWP_WRITEOK; | |
5d337b91 | 1519 | spin_unlock(&swap_lock); |
fb4f88dc | 1520 | |
1da177e4 LT |
1521 | current->flags |= PF_SWAPOFF; |
1522 | err = try_to_unuse(type); | |
1523 | current->flags &= ~PF_SWAPOFF; | |
1524 | ||
1da177e4 LT |
1525 | if (err) { |
1526 | /* re-insert swap space back into swap_list */ | |
5d337b91 | 1527 | spin_lock(&swap_lock); |
78ecba08 HD |
1528 | if (p->prio < 0) |
1529 | p->prio = --least_priority; | |
1530 | prev = -1; | |
1531 | for (i = swap_list.head; i >= 0; i = swap_info[i].next) { | |
1da177e4 LT |
1532 | if (p->prio >= swap_info[i].prio) |
1533 | break; | |
78ecba08 HD |
1534 | prev = i; |
1535 | } | |
1da177e4 LT |
1536 | p->next = i; |
1537 | if (prev < 0) | |
1538 | swap_list.head = swap_list.next = p - swap_info; | |
1539 | else | |
1540 | swap_info[prev].next = p - swap_info; | |
1541 | nr_swap_pages += p->pages; | |
1542 | total_swap_pages += p->pages; | |
1543 | p->flags |= SWP_WRITEOK; | |
5d337b91 | 1544 | spin_unlock(&swap_lock); |
1da177e4 LT |
1545 | goto out_dput; |
1546 | } | |
52b7efdb HD |
1547 | |
1548 | /* wait for any unplug function to finish */ | |
1549 | down_write(&swap_unplug_sem); | |
1550 | up_write(&swap_unplug_sem); | |
1551 | ||
5d337b91 | 1552 | destroy_swap_extents(p); |
fc0abb14 | 1553 | mutex_lock(&swapon_mutex); |
5d337b91 HD |
1554 | spin_lock(&swap_lock); |
1555 | drain_mmlist(); | |
1556 | ||
52b7efdb | 1557 | /* wait for anyone still in scan_swap_map */ |
52b7efdb HD |
1558 | p->highest_bit = 0; /* cuts scans short */ |
1559 | while (p->flags >= SWP_SCANNING) { | |
5d337b91 | 1560 | spin_unlock(&swap_lock); |
13e4b57f | 1561 | schedule_timeout_uninterruptible(1); |
5d337b91 | 1562 | spin_lock(&swap_lock); |
52b7efdb | 1563 | } |
52b7efdb | 1564 | |
1da177e4 LT |
1565 | swap_file = p->swap_file; |
1566 | p->swap_file = NULL; | |
1567 | p->max = 0; | |
1568 | swap_map = p->swap_map; | |
1569 | p->swap_map = NULL; | |
1570 | p->flags = 0; | |
5d337b91 | 1571 | spin_unlock(&swap_lock); |
fc0abb14 | 1572 | mutex_unlock(&swapon_mutex); |
1da177e4 | 1573 | vfree(swap_map); |
27a7faa0 KH |
1574 | /* Destroy swap account informatin */ |
1575 | swap_cgroup_swapoff(type); | |
1576 | ||
1da177e4 LT |
1577 | inode = mapping->host; |
1578 | if (S_ISBLK(inode->i_mode)) { | |
1579 | struct block_device *bdev = I_BDEV(inode); | |
1580 | set_blocksize(bdev, p->old_block_size); | |
1581 | bd_release(bdev); | |
1582 | } else { | |
1b1dcc1b | 1583 | mutex_lock(&inode->i_mutex); |
1da177e4 | 1584 | inode->i_flags &= ~S_SWAPFILE; |
1b1dcc1b | 1585 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
1586 | } |
1587 | filp_close(swap_file, NULL); | |
1588 | err = 0; | |
1589 | ||
1590 | out_dput: | |
1591 | filp_close(victim, NULL); | |
1592 | out: | |
1593 | return err; | |
1594 | } | |
1595 | ||
1596 | #ifdef CONFIG_PROC_FS | |
1597 | /* iterator */ | |
1598 | static void *swap_start(struct seq_file *swap, loff_t *pos) | |
1599 | { | |
1600 | struct swap_info_struct *ptr = swap_info; | |
1601 | int i; | |
1602 | loff_t l = *pos; | |
1603 | ||
fc0abb14 | 1604 | mutex_lock(&swapon_mutex); |
1da177e4 | 1605 | |
881e4aab SS |
1606 | if (!l) |
1607 | return SEQ_START_TOKEN; | |
1608 | ||
1da177e4 LT |
1609 | for (i = 0; i < nr_swapfiles; i++, ptr++) { |
1610 | if (!(ptr->flags & SWP_USED) || !ptr->swap_map) | |
1611 | continue; | |
881e4aab | 1612 | if (!--l) |
1da177e4 LT |
1613 | return ptr; |
1614 | } | |
1615 | ||
1616 | return NULL; | |
1617 | } | |
1618 | ||
1619 | static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) | |
1620 | { | |
881e4aab | 1621 | struct swap_info_struct *ptr; |
1da177e4 LT |
1622 | struct swap_info_struct *endptr = swap_info + nr_swapfiles; |
1623 | ||
881e4aab SS |
1624 | if (v == SEQ_START_TOKEN) |
1625 | ptr = swap_info; | |
1626 | else { | |
1627 | ptr = v; | |
1628 | ptr++; | |
1629 | } | |
1630 | ||
1631 | for (; ptr < endptr; ptr++) { | |
1da177e4 LT |
1632 | if (!(ptr->flags & SWP_USED) || !ptr->swap_map) |
1633 | continue; | |
1634 | ++*pos; | |
1635 | return ptr; | |
1636 | } | |
1637 | ||
1638 | return NULL; | |
1639 | } | |
1640 | ||
1641 | static void swap_stop(struct seq_file *swap, void *v) | |
1642 | { | |
fc0abb14 | 1643 | mutex_unlock(&swapon_mutex); |
1da177e4 LT |
1644 | } |
1645 | ||
1646 | static int swap_show(struct seq_file *swap, void *v) | |
1647 | { | |
1648 | struct swap_info_struct *ptr = v; | |
1649 | struct file *file; | |
1650 | int len; | |
1651 | ||
881e4aab SS |
1652 | if (ptr == SEQ_START_TOKEN) { |
1653 | seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n"); | |
1654 | return 0; | |
1655 | } | |
1da177e4 LT |
1656 | |
1657 | file = ptr->swap_file; | |
c32c2f63 | 1658 | len = seq_path(swap, &file->f_path, " \t\n\\"); |
6eb396dc | 1659 | seq_printf(swap, "%*s%s\t%u\t%u\t%d\n", |
886bb7e9 HD |
1660 | len < 40 ? 40 - len : 1, " ", |
1661 | S_ISBLK(file->f_path.dentry->d_inode->i_mode) ? | |
1da177e4 | 1662 | "partition" : "file\t", |
886bb7e9 HD |
1663 | ptr->pages << (PAGE_SHIFT - 10), |
1664 | ptr->inuse_pages << (PAGE_SHIFT - 10), | |
1665 | ptr->prio); | |
1da177e4 LT |
1666 | return 0; |
1667 | } | |
1668 | ||
15ad7cdc | 1669 | static const struct seq_operations swaps_op = { |
1da177e4 LT |
1670 | .start = swap_start, |
1671 | .next = swap_next, | |
1672 | .stop = swap_stop, | |
1673 | .show = swap_show | |
1674 | }; | |
1675 | ||
1676 | static int swaps_open(struct inode *inode, struct file *file) | |
1677 | { | |
1678 | return seq_open(file, &swaps_op); | |
1679 | } | |
1680 | ||
15ad7cdc | 1681 | static const struct file_operations proc_swaps_operations = { |
1da177e4 LT |
1682 | .open = swaps_open, |
1683 | .read = seq_read, | |
1684 | .llseek = seq_lseek, | |
1685 | .release = seq_release, | |
1686 | }; | |
1687 | ||
1688 | static int __init procswaps_init(void) | |
1689 | { | |
3d71f86f | 1690 | proc_create("swaps", 0, NULL, &proc_swaps_operations); |
1da177e4 LT |
1691 | return 0; |
1692 | } | |
1693 | __initcall(procswaps_init); | |
1694 | #endif /* CONFIG_PROC_FS */ | |
1695 | ||
1796316a JB |
1696 | #ifdef MAX_SWAPFILES_CHECK |
1697 | static int __init max_swapfiles_check(void) | |
1698 | { | |
1699 | MAX_SWAPFILES_CHECK(); | |
1700 | return 0; | |
1701 | } | |
1702 | late_initcall(max_swapfiles_check); | |
1703 | #endif | |
1704 | ||
1da177e4 LT |
1705 | /* |
1706 | * Written 01/25/92 by Simmule Turner, heavily changed by Linus. | |
1707 | * | |
1708 | * The swapon system call | |
1709 | */ | |
c4ea37c2 | 1710 | SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) |
1da177e4 LT |
1711 | { |
1712 | struct swap_info_struct * p; | |
1713 | char *name = NULL; | |
1714 | struct block_device *bdev = NULL; | |
1715 | struct file *swap_file = NULL; | |
1716 | struct address_space *mapping; | |
1717 | unsigned int type; | |
1718 | int i, prev; | |
1719 | int error; | |
1da177e4 | 1720 | union swap_header *swap_header = NULL; |
6eb396dc HD |
1721 | unsigned int nr_good_pages = 0; |
1722 | int nr_extents = 0; | |
53092a74 | 1723 | sector_t span; |
1da177e4 | 1724 | unsigned long maxpages = 1; |
73fd8748 | 1725 | unsigned long swapfilepages; |
78ecba08 | 1726 | unsigned short *swap_map = NULL; |
1da177e4 LT |
1727 | struct page *page = NULL; |
1728 | struct inode *inode = NULL; | |
1729 | int did_down = 0; | |
1730 | ||
1731 | if (!capable(CAP_SYS_ADMIN)) | |
1732 | return -EPERM; | |
5d337b91 | 1733 | spin_lock(&swap_lock); |
1da177e4 LT |
1734 | p = swap_info; |
1735 | for (type = 0 ; type < nr_swapfiles ; type++,p++) | |
1736 | if (!(p->flags & SWP_USED)) | |
1737 | break; | |
1738 | error = -EPERM; | |
0697212a | 1739 | if (type >= MAX_SWAPFILES) { |
5d337b91 | 1740 | spin_unlock(&swap_lock); |
1da177e4 LT |
1741 | goto out; |
1742 | } | |
1743 | if (type >= nr_swapfiles) | |
1744 | nr_swapfiles = type+1; | |
78ecba08 | 1745 | memset(p, 0, sizeof(*p)); |
1da177e4 LT |
1746 | INIT_LIST_HEAD(&p->extent_list); |
1747 | p->flags = SWP_USED; | |
1da177e4 | 1748 | p->next = -1; |
5d337b91 | 1749 | spin_unlock(&swap_lock); |
1da177e4 LT |
1750 | name = getname(specialfile); |
1751 | error = PTR_ERR(name); | |
1752 | if (IS_ERR(name)) { | |
1753 | name = NULL; | |
1754 | goto bad_swap_2; | |
1755 | } | |
1756 | swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0); | |
1757 | error = PTR_ERR(swap_file); | |
1758 | if (IS_ERR(swap_file)) { | |
1759 | swap_file = NULL; | |
1760 | goto bad_swap_2; | |
1761 | } | |
1762 | ||
1763 | p->swap_file = swap_file; | |
1764 | mapping = swap_file->f_mapping; | |
1765 | inode = mapping->host; | |
1766 | ||
1767 | error = -EBUSY; | |
1768 | for (i = 0; i < nr_swapfiles; i++) { | |
1769 | struct swap_info_struct *q = &swap_info[i]; | |
1770 | ||
1771 | if (i == type || !q->swap_file) | |
1772 | continue; | |
1773 | if (mapping == q->swap_file->f_mapping) | |
1774 | goto bad_swap; | |
1775 | } | |
1776 | ||
1777 | error = -EINVAL; | |
1778 | if (S_ISBLK(inode->i_mode)) { | |
1779 | bdev = I_BDEV(inode); | |
1780 | error = bd_claim(bdev, sys_swapon); | |
1781 | if (error < 0) { | |
1782 | bdev = NULL; | |
f7b3a435 | 1783 | error = -EINVAL; |
1da177e4 LT |
1784 | goto bad_swap; |
1785 | } | |
1786 | p->old_block_size = block_size(bdev); | |
1787 | error = set_blocksize(bdev, PAGE_SIZE); | |
1788 | if (error < 0) | |
1789 | goto bad_swap; | |
1790 | p->bdev = bdev; | |
1791 | } else if (S_ISREG(inode->i_mode)) { | |
1792 | p->bdev = inode->i_sb->s_bdev; | |
1b1dcc1b | 1793 | mutex_lock(&inode->i_mutex); |
1da177e4 LT |
1794 | did_down = 1; |
1795 | if (IS_SWAPFILE(inode)) { | |
1796 | error = -EBUSY; | |
1797 | goto bad_swap; | |
1798 | } | |
1799 | } else { | |
1800 | goto bad_swap; | |
1801 | } | |
1802 | ||
73fd8748 | 1803 | swapfilepages = i_size_read(inode) >> PAGE_SHIFT; |
1da177e4 LT |
1804 | |
1805 | /* | |
1806 | * Read the swap header. | |
1807 | */ | |
1808 | if (!mapping->a_ops->readpage) { | |
1809 | error = -EINVAL; | |
1810 | goto bad_swap; | |
1811 | } | |
090d2b18 | 1812 | page = read_mapping_page(mapping, 0, swap_file); |
1da177e4 LT |
1813 | if (IS_ERR(page)) { |
1814 | error = PTR_ERR(page); | |
1815 | goto bad_swap; | |
1816 | } | |
81e33971 | 1817 | swap_header = kmap(page); |
1da177e4 | 1818 | |
81e33971 | 1819 | if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) { |
e97a3111 | 1820 | printk(KERN_ERR "Unable to find swap-space signature\n"); |
1da177e4 LT |
1821 | error = -EINVAL; |
1822 | goto bad_swap; | |
1823 | } | |
886bb7e9 | 1824 | |
81e33971 HD |
1825 | /* swap partition endianess hack... */ |
1826 | if (swab32(swap_header->info.version) == 1) { | |
1827 | swab32s(&swap_header->info.version); | |
1828 | swab32s(&swap_header->info.last_page); | |
1829 | swab32s(&swap_header->info.nr_badpages); | |
1830 | for (i = 0; i < swap_header->info.nr_badpages; i++) | |
1831 | swab32s(&swap_header->info.badpages[i]); | |
1832 | } | |
1833 | /* Check the swap header's sub-version */ | |
1834 | if (swap_header->info.version != 1) { | |
1835 | printk(KERN_WARNING | |
1836 | "Unable to handle swap header version %d\n", | |
1837 | swap_header->info.version); | |
1da177e4 LT |
1838 | error = -EINVAL; |
1839 | goto bad_swap; | |
81e33971 | 1840 | } |
1da177e4 | 1841 | |
81e33971 HD |
1842 | p->lowest_bit = 1; |
1843 | p->cluster_next = 1; | |
52b7efdb | 1844 | |
81e33971 HD |
1845 | /* |
1846 | * Find out how many pages are allowed for a single swap | |
1847 | * device. There are two limiting factors: 1) the number of | |
1848 | * bits for the swap offset in the swp_entry_t type and | |
1849 | * 2) the number of bits in the a swap pte as defined by | |
1850 | * the different architectures. In order to find the | |
1851 | * largest possible bit mask a swap entry with swap type 0 | |
1852 | * and swap offset ~0UL is created, encoded to a swap pte, | |
1853 | * decoded to a swp_entry_t again and finally the swap | |
1854 | * offset is extracted. This will mask all the bits from | |
1855 | * the initial ~0UL mask that can't be encoded in either | |
1856 | * the swp_entry_t or the architecture definition of a | |
1857 | * swap pte. | |
1858 | */ | |
1859 | maxpages = swp_offset(pte_to_swp_entry( | |
1860 | swp_entry_to_pte(swp_entry(0, ~0UL)))) - 1; | |
1861 | if (maxpages > swap_header->info.last_page) | |
1862 | maxpages = swap_header->info.last_page; | |
1863 | p->highest_bit = maxpages - 1; | |
1da177e4 | 1864 | |
81e33971 HD |
1865 | error = -EINVAL; |
1866 | if (!maxpages) | |
1867 | goto bad_swap; | |
1868 | if (swapfilepages && maxpages > swapfilepages) { | |
1869 | printk(KERN_WARNING | |
1870 | "Swap area shorter than signature indicates\n"); | |
1871 | goto bad_swap; | |
1872 | } | |
1873 | if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) | |
1874 | goto bad_swap; | |
1875 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) | |
1876 | goto bad_swap; | |
cd105df4 | 1877 | |
81e33971 HD |
1878 | /* OK, set up the swap map and apply the bad block list */ |
1879 | swap_map = vmalloc(maxpages * sizeof(short)); | |
1880 | if (!swap_map) { | |
1881 | error = -ENOMEM; | |
1882 | goto bad_swap; | |
1883 | } | |
1da177e4 | 1884 | |
81e33971 HD |
1885 | memset(swap_map, 0, maxpages * sizeof(short)); |
1886 | for (i = 0; i < swap_header->info.nr_badpages; i++) { | |
1887 | int page_nr = swap_header->info.badpages[i]; | |
1888 | if (page_nr <= 0 || page_nr >= swap_header->info.last_page) { | |
1889 | error = -EINVAL; | |
1da177e4 | 1890 | goto bad_swap; |
81e33971 HD |
1891 | } |
1892 | swap_map[page_nr] = SWAP_MAP_BAD; | |
1da177e4 | 1893 | } |
27a7faa0 KH |
1894 | |
1895 | error = swap_cgroup_swapon(type, maxpages); | |
1896 | if (error) | |
1897 | goto bad_swap; | |
1898 | ||
81e33971 HD |
1899 | nr_good_pages = swap_header->info.last_page - |
1900 | swap_header->info.nr_badpages - | |
1901 | 1 /* header page */; | |
e2244ec2 | 1902 | |
e2244ec2 | 1903 | if (nr_good_pages) { |
78ecba08 | 1904 | swap_map[0] = SWAP_MAP_BAD; |
e2244ec2 HD |
1905 | p->max = maxpages; |
1906 | p->pages = nr_good_pages; | |
53092a74 HD |
1907 | nr_extents = setup_swap_extents(p, &span); |
1908 | if (nr_extents < 0) { | |
1909 | error = nr_extents; | |
e2244ec2 | 1910 | goto bad_swap; |
53092a74 | 1911 | } |
e2244ec2 HD |
1912 | nr_good_pages = p->pages; |
1913 | } | |
1da177e4 LT |
1914 | if (!nr_good_pages) { |
1915 | printk(KERN_WARNING "Empty swap-file\n"); | |
1916 | error = -EINVAL; | |
1917 | goto bad_swap; | |
1918 | } | |
1da177e4 | 1919 | |
20137a49 HD |
1920 | if (blk_queue_nonrot(bdev_get_queue(p->bdev))) { |
1921 | p->flags |= SWP_SOLIDSTATE; | |
20137a49 HD |
1922 | p->cluster_next = 1 + (random32() % p->highest_bit); |
1923 | } | |
6a6ba831 HD |
1924 | if (discard_swap(p) == 0) |
1925 | p->flags |= SWP_DISCARDABLE; | |
1926 | ||
fc0abb14 | 1927 | mutex_lock(&swapon_mutex); |
5d337b91 | 1928 | spin_lock(&swap_lock); |
78ecba08 HD |
1929 | if (swap_flags & SWAP_FLAG_PREFER) |
1930 | p->prio = | |
1931 | (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; | |
1932 | else | |
1933 | p->prio = --least_priority; | |
1934 | p->swap_map = swap_map; | |
22c6f8fd | 1935 | p->flags |= SWP_WRITEOK; |
1da177e4 LT |
1936 | nr_swap_pages += nr_good_pages; |
1937 | total_swap_pages += nr_good_pages; | |
53092a74 | 1938 | |
6eb396dc | 1939 | printk(KERN_INFO "Adding %uk swap on %s. " |
20137a49 | 1940 | "Priority:%d extents:%d across:%lluk %s%s\n", |
53092a74 | 1941 | nr_good_pages<<(PAGE_SHIFT-10), name, p->prio, |
6a6ba831 | 1942 | nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), |
20137a49 HD |
1943 | (p->flags & SWP_SOLIDSTATE) ? "SS" : "", |
1944 | (p->flags & SWP_DISCARDABLE) ? "D" : ""); | |
1da177e4 LT |
1945 | |
1946 | /* insert swap space into swap_list: */ | |
1947 | prev = -1; | |
1948 | for (i = swap_list.head; i >= 0; i = swap_info[i].next) { | |
1949 | if (p->prio >= swap_info[i].prio) { | |
1950 | break; | |
1951 | } | |
1952 | prev = i; | |
1953 | } | |
1954 | p->next = i; | |
1955 | if (prev < 0) { | |
1956 | swap_list.head = swap_list.next = p - swap_info; | |
1957 | } else { | |
1958 | swap_info[prev].next = p - swap_info; | |
1959 | } | |
5d337b91 | 1960 | spin_unlock(&swap_lock); |
fc0abb14 | 1961 | mutex_unlock(&swapon_mutex); |
1da177e4 LT |
1962 | error = 0; |
1963 | goto out; | |
1964 | bad_swap: | |
1965 | if (bdev) { | |
1966 | set_blocksize(bdev, p->old_block_size); | |
1967 | bd_release(bdev); | |
1968 | } | |
4cd3bb10 | 1969 | destroy_swap_extents(p); |
27a7faa0 | 1970 | swap_cgroup_swapoff(type); |
1da177e4 | 1971 | bad_swap_2: |
5d337b91 | 1972 | spin_lock(&swap_lock); |
1da177e4 | 1973 | p->swap_file = NULL; |
1da177e4 | 1974 | p->flags = 0; |
5d337b91 | 1975 | spin_unlock(&swap_lock); |
1da177e4 LT |
1976 | vfree(swap_map); |
1977 | if (swap_file) | |
1978 | filp_close(swap_file, NULL); | |
1979 | out: | |
1980 | if (page && !IS_ERR(page)) { | |
1981 | kunmap(page); | |
1982 | page_cache_release(page); | |
1983 | } | |
1984 | if (name) | |
1985 | putname(name); | |
1986 | if (did_down) { | |
1987 | if (!error) | |
1988 | inode->i_flags |= S_SWAPFILE; | |
1b1dcc1b | 1989 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
1990 | } |
1991 | return error; | |
1992 | } | |
1993 | ||
1994 | void si_swapinfo(struct sysinfo *val) | |
1995 | { | |
1996 | unsigned int i; | |
1997 | unsigned long nr_to_be_unused = 0; | |
1998 | ||
5d337b91 | 1999 | spin_lock(&swap_lock); |
1da177e4 LT |
2000 | for (i = 0; i < nr_swapfiles; i++) { |
2001 | if (!(swap_info[i].flags & SWP_USED) || | |
2002 | (swap_info[i].flags & SWP_WRITEOK)) | |
2003 | continue; | |
2004 | nr_to_be_unused += swap_info[i].inuse_pages; | |
2005 | } | |
2006 | val->freeswap = nr_swap_pages + nr_to_be_unused; | |
2007 | val->totalswap = total_swap_pages + nr_to_be_unused; | |
5d337b91 | 2008 | spin_unlock(&swap_lock); |
1da177e4 LT |
2009 | } |
2010 | ||
2011 | /* | |
2012 | * Verify that a swap entry is valid and increment its swap map count. | |
2013 | * | |
2014 | * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as | |
2015 | * "permanent", but will be reclaimed by the next swapoff. | |
355cfa73 KH |
2016 | * Returns error code in following case. |
2017 | * - success -> 0 | |
2018 | * - swp_entry is invalid -> EINVAL | |
2019 | * - swp_entry is migration entry -> EINVAL | |
2020 | * - swap-cache reference is requested but there is already one. -> EEXIST | |
2021 | * - swap-cache reference is requested but the entry is not used. -> ENOENT | |
1da177e4 | 2022 | */ |
355cfa73 | 2023 | static int __swap_duplicate(swp_entry_t entry, bool cache) |
1da177e4 LT |
2024 | { |
2025 | struct swap_info_struct * p; | |
2026 | unsigned long offset, type; | |
355cfa73 KH |
2027 | int result = -EINVAL; |
2028 | int count; | |
2029 | bool has_cache; | |
1da177e4 | 2030 | |
0697212a | 2031 | if (is_migration_entry(entry)) |
355cfa73 | 2032 | return -EINVAL; |
0697212a | 2033 | |
1da177e4 LT |
2034 | type = swp_type(entry); |
2035 | if (type >= nr_swapfiles) | |
2036 | goto bad_file; | |
2037 | p = type + swap_info; | |
2038 | offset = swp_offset(entry); | |
2039 | ||
5d337b91 | 2040 | spin_lock(&swap_lock); |
355cfa73 KH |
2041 | |
2042 | if (unlikely(offset >= p->max)) | |
2043 | goto unlock_out; | |
2044 | ||
2045 | count = swap_count(p->swap_map[offset]); | |
2046 | has_cache = swap_has_cache(p->swap_map[offset]); | |
2047 | ||
2048 | if (cache == SWAP_CACHE) { /* called for swapcache/swapin-readahead */ | |
2049 | ||
2050 | /* set SWAP_HAS_CACHE if there is no cache and entry is used */ | |
2051 | if (!has_cache && count) { | |
2052 | p->swap_map[offset] = encode_swapmap(count, true); | |
2053 | result = 0; | |
2054 | } else if (has_cache) /* someone added cache */ | |
2055 | result = -EEXIST; | |
2056 | else if (!count) /* no users */ | |
2057 | result = -ENOENT; | |
2058 | ||
2059 | } else if (count || has_cache) { | |
2060 | if (count < SWAP_MAP_MAX - 1) { | |
2061 | p->swap_map[offset] = encode_swapmap(count + 1, | |
2062 | has_cache); | |
2063 | result = 0; | |
2064 | } else if (count <= SWAP_MAP_MAX) { | |
1da177e4 | 2065 | if (swap_overflow++ < 5) |
355cfa73 KH |
2066 | printk(KERN_WARNING |
2067 | "swap_dup: swap entry overflow\n"); | |
2068 | p->swap_map[offset] = encode_swapmap(SWAP_MAP_MAX, | |
2069 | has_cache); | |
2070 | result = 0; | |
1da177e4 | 2071 | } |
355cfa73 KH |
2072 | } else |
2073 | result = -ENOENT; /* unused swap entry */ | |
2074 | unlock_out: | |
5d337b91 | 2075 | spin_unlock(&swap_lock); |
1da177e4 LT |
2076 | out: |
2077 | return result; | |
2078 | ||
2079 | bad_file: | |
2080 | printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val); | |
2081 | goto out; | |
2082 | } | |
355cfa73 KH |
2083 | /* |
2084 | * increase reference count of swap entry by 1. | |
2085 | */ | |
2086 | void swap_duplicate(swp_entry_t entry) | |
2087 | { | |
2088 | __swap_duplicate(entry, SWAP_MAP); | |
2089 | } | |
1da177e4 | 2090 | |
cb4b86ba | 2091 | /* |
355cfa73 KH |
2092 | * @entry: swap entry for which we allocate swap cache. |
2093 | * | |
cb4b86ba | 2094 | * Called when allocating swap cache for exising swap entry, |
355cfa73 KH |
2095 | * This can return error codes. Returns 0 at success. |
2096 | * -EBUSY means there is a swap cache. | |
2097 | * Note: return code is different from swap_duplicate(). | |
cb4b86ba KH |
2098 | */ |
2099 | int swapcache_prepare(swp_entry_t entry) | |
2100 | { | |
355cfa73 | 2101 | return __swap_duplicate(entry, SWAP_CACHE); |
cb4b86ba KH |
2102 | } |
2103 | ||
2104 | ||
1da177e4 LT |
2105 | struct swap_info_struct * |
2106 | get_swap_info_struct(unsigned type) | |
2107 | { | |
2108 | return &swap_info[type]; | |
2109 | } | |
2110 | ||
2111 | /* | |
5d337b91 | 2112 | * swap_lock prevents swap_map being freed. Don't grab an extra |
1da177e4 LT |
2113 | * reference on the swaphandle, it doesn't matter if it becomes unused. |
2114 | */ | |
2115 | int valid_swaphandles(swp_entry_t entry, unsigned long *offset) | |
2116 | { | |
8952898b | 2117 | struct swap_info_struct *si; |
3f9e7949 | 2118 | int our_page_cluster = page_cluster; |
8952898b HD |
2119 | pgoff_t target, toff; |
2120 | pgoff_t base, end; | |
2121 | int nr_pages = 0; | |
1da177e4 | 2122 | |
3f9e7949 | 2123 | if (!our_page_cluster) /* no readahead */ |
1da177e4 | 2124 | return 0; |
8952898b HD |
2125 | |
2126 | si = &swap_info[swp_type(entry)]; | |
2127 | target = swp_offset(entry); | |
2128 | base = (target >> our_page_cluster) << our_page_cluster; | |
2129 | end = base + (1 << our_page_cluster); | |
2130 | if (!base) /* first page is swap header */ | |
2131 | base++; | |
1da177e4 | 2132 | |
5d337b91 | 2133 | spin_lock(&swap_lock); |
8952898b HD |
2134 | if (end > si->max) /* don't go beyond end of map */ |
2135 | end = si->max; | |
2136 | ||
2137 | /* Count contiguous allocated slots above our target */ | |
2138 | for (toff = target; ++toff < end; nr_pages++) { | |
2139 | /* Don't read in free or bad pages */ | |
2140 | if (!si->swap_map[toff]) | |
2141 | break; | |
355cfa73 | 2142 | if (swap_count(si->swap_map[toff]) == SWAP_MAP_BAD) |
1da177e4 | 2143 | break; |
8952898b HD |
2144 | } |
2145 | /* Count contiguous allocated slots below our target */ | |
2146 | for (toff = target; --toff >= base; nr_pages++) { | |
1da177e4 | 2147 | /* Don't read in free or bad pages */ |
8952898b | 2148 | if (!si->swap_map[toff]) |
1da177e4 | 2149 | break; |
355cfa73 | 2150 | if (swap_count(si->swap_map[toff]) == SWAP_MAP_BAD) |
1da177e4 | 2151 | break; |
8952898b | 2152 | } |
5d337b91 | 2153 | spin_unlock(&swap_lock); |
8952898b HD |
2154 | |
2155 | /* | |
2156 | * Indicate starting offset, and return number of pages to get: | |
2157 | * if only 1, say 0, since there's then no readahead to be done. | |
2158 | */ | |
2159 | *offset = ++toff; | |
2160 | return nr_pages? ++nr_pages: 0; | |
1da177e4 | 2161 | } |