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 | ||
8 | #include <linux/config.h> | |
9 | #include <linux/mm.h> | |
10 | #include <linux/hugetlb.h> | |
11 | #include <linux/mman.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/kernel_stat.h> | |
14 | #include <linux/swap.h> | |
15 | #include <linux/vmalloc.h> | |
16 | #include <linux/pagemap.h> | |
17 | #include <linux/namei.h> | |
18 | #include <linux/shm.h> | |
19 | #include <linux/blkdev.h> | |
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> | |
c59ede7b | 28 | #include <linux/capability.h> |
1da177e4 LT |
29 | #include <linux/syscalls.h> |
30 | ||
31 | #include <asm/pgtable.h> | |
32 | #include <asm/tlbflush.h> | |
33 | #include <linux/swapops.h> | |
34 | ||
5d337b91 | 35 | DEFINE_SPINLOCK(swap_lock); |
1da177e4 LT |
36 | unsigned int nr_swapfiles; |
37 | long total_swap_pages; | |
38 | static int swap_overflow; | |
39 | ||
1da177e4 LT |
40 | static const char Bad_file[] = "Bad swap file entry "; |
41 | static const char Unused_file[] = "Unused swap file entry "; | |
42 | static const char Bad_offset[] = "Bad swap offset entry "; | |
43 | static const char Unused_offset[] = "Unused swap offset entry "; | |
44 | ||
45 | struct swap_list_t swap_list = {-1, -1}; | |
46 | ||
47 | struct swap_info_struct swap_info[MAX_SWAPFILES]; | |
48 | ||
49 | static DECLARE_MUTEX(swapon_sem); | |
50 | ||
51 | /* | |
52 | * We need this because the bdev->unplug_fn can sleep and we cannot | |
5d337b91 | 53 | * hold swap_lock while calling the unplug_fn. And swap_lock |
1da177e4 LT |
54 | * cannot be turned into a semaphore. |
55 | */ | |
56 | static DECLARE_RWSEM(swap_unplug_sem); | |
57 | ||
1da177e4 LT |
58 | void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page) |
59 | { | |
60 | swp_entry_t entry; | |
61 | ||
62 | down_read(&swap_unplug_sem); | |
4c21e2f2 | 63 | entry.val = page_private(page); |
1da177e4 LT |
64 | if (PageSwapCache(page)) { |
65 | struct block_device *bdev = swap_info[swp_type(entry)].bdev; | |
66 | struct backing_dev_info *bdi; | |
67 | ||
68 | /* | |
69 | * If the page is removed from swapcache from under us (with a | |
70 | * racy try_to_unuse/swapoff) we need an additional reference | |
4c21e2f2 HD |
71 | * count to avoid reading garbage from page_private(page) above. |
72 | * If the WARN_ON triggers during a swapoff it maybe the race | |
1da177e4 LT |
73 | * condition and it's harmless. However if it triggers without |
74 | * swapoff it signals a problem. | |
75 | */ | |
76 | WARN_ON(page_count(page) <= 1); | |
77 | ||
78 | bdi = bdev->bd_inode->i_mapping->backing_dev_info; | |
ba32311e | 79 | blk_run_backing_dev(bdi, page); |
1da177e4 LT |
80 | } |
81 | up_read(&swap_unplug_sem); | |
82 | } | |
83 | ||
048c27fd HD |
84 | #define SWAPFILE_CLUSTER 256 |
85 | #define LATENCY_LIMIT 256 | |
86 | ||
6eb396dc | 87 | static inline unsigned long scan_swap_map(struct swap_info_struct *si) |
1da177e4 | 88 | { |
7dfad418 | 89 | unsigned long offset, last_in_cluster; |
048c27fd | 90 | int latency_ration = LATENCY_LIMIT; |
7dfad418 | 91 | |
1da177e4 | 92 | /* |
7dfad418 HD |
93 | * We try to cluster swap pages by allocating them sequentially |
94 | * in swap. Once we've allocated SWAPFILE_CLUSTER pages this | |
95 | * way, however, we resort to first-free allocation, starting | |
96 | * a new cluster. This prevents us from scattering swap pages | |
97 | * all over the entire swap partition, so that we reduce | |
98 | * overall disk seek times between swap pages. -- sct | |
99 | * But we do now try to find an empty cluster. -Andrea | |
100 | */ | |
101 | ||
52b7efdb | 102 | si->flags += SWP_SCANNING; |
7dfad418 HD |
103 | if (unlikely(!si->cluster_nr)) { |
104 | si->cluster_nr = SWAPFILE_CLUSTER - 1; | |
105 | if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) | |
106 | goto lowest; | |
5d337b91 | 107 | spin_unlock(&swap_lock); |
7dfad418 HD |
108 | |
109 | offset = si->lowest_bit; | |
110 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; | |
111 | ||
112 | /* Locate the first empty (unaligned) cluster */ | |
113 | for (; last_in_cluster <= si->highest_bit; offset++) { | |
1da177e4 | 114 | if (si->swap_map[offset]) |
7dfad418 HD |
115 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
116 | else if (offset == last_in_cluster) { | |
5d337b91 | 117 | spin_lock(&swap_lock); |
7dfad418 HD |
118 | si->cluster_next = offset-SWAPFILE_CLUSTER-1; |
119 | goto cluster; | |
1da177e4 | 120 | } |
048c27fd HD |
121 | if (unlikely(--latency_ration < 0)) { |
122 | cond_resched(); | |
123 | latency_ration = LATENCY_LIMIT; | |
124 | } | |
7dfad418 | 125 | } |
5d337b91 | 126 | spin_lock(&swap_lock); |
7dfad418 | 127 | goto lowest; |
1da177e4 | 128 | } |
7dfad418 HD |
129 | |
130 | si->cluster_nr--; | |
131 | cluster: | |
132 | offset = si->cluster_next; | |
133 | if (offset > si->highest_bit) | |
134 | lowest: offset = si->lowest_bit; | |
52b7efdb HD |
135 | checks: if (!(si->flags & SWP_WRITEOK)) |
136 | goto no_page; | |
7dfad418 HD |
137 | if (!si->highest_bit) |
138 | goto no_page; | |
139 | if (!si->swap_map[offset]) { | |
52b7efdb | 140 | if (offset == si->lowest_bit) |
1da177e4 LT |
141 | si->lowest_bit++; |
142 | if (offset == si->highest_bit) | |
143 | si->highest_bit--; | |
7dfad418 HD |
144 | si->inuse_pages++; |
145 | if (si->inuse_pages == si->pages) { | |
1da177e4 LT |
146 | si->lowest_bit = si->max; |
147 | si->highest_bit = 0; | |
148 | } | |
149 | si->swap_map[offset] = 1; | |
7dfad418 | 150 | si->cluster_next = offset + 1; |
52b7efdb | 151 | si->flags -= SWP_SCANNING; |
1da177e4 LT |
152 | return offset; |
153 | } | |
7dfad418 | 154 | |
5d337b91 | 155 | spin_unlock(&swap_lock); |
7dfad418 | 156 | while (++offset <= si->highest_bit) { |
52b7efdb | 157 | if (!si->swap_map[offset]) { |
5d337b91 | 158 | spin_lock(&swap_lock); |
52b7efdb HD |
159 | goto checks; |
160 | } | |
048c27fd HD |
161 | if (unlikely(--latency_ration < 0)) { |
162 | cond_resched(); | |
163 | latency_ration = LATENCY_LIMIT; | |
164 | } | |
7dfad418 | 165 | } |
5d337b91 | 166 | spin_lock(&swap_lock); |
7dfad418 HD |
167 | goto lowest; |
168 | ||
169 | no_page: | |
52b7efdb | 170 | si->flags -= SWP_SCANNING; |
1da177e4 LT |
171 | return 0; |
172 | } | |
173 | ||
174 | swp_entry_t get_swap_page(void) | |
175 | { | |
fb4f88dc HD |
176 | struct swap_info_struct *si; |
177 | pgoff_t offset; | |
178 | int type, next; | |
179 | int wrapped = 0; | |
1da177e4 | 180 | |
5d337b91 | 181 | spin_lock(&swap_lock); |
1da177e4 | 182 | if (nr_swap_pages <= 0) |
fb4f88dc HD |
183 | goto noswap; |
184 | nr_swap_pages--; | |
185 | ||
186 | for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) { | |
187 | si = swap_info + type; | |
188 | next = si->next; | |
189 | if (next < 0 || | |
190 | (!wrapped && si->prio != swap_info[next].prio)) { | |
191 | next = swap_list.head; | |
192 | wrapped++; | |
1da177e4 | 193 | } |
fb4f88dc HD |
194 | |
195 | if (!si->highest_bit) | |
196 | continue; | |
197 | if (!(si->flags & SWP_WRITEOK)) | |
198 | continue; | |
199 | ||
200 | swap_list.next = next; | |
fb4f88dc | 201 | offset = scan_swap_map(si); |
5d337b91 HD |
202 | if (offset) { |
203 | spin_unlock(&swap_lock); | |
fb4f88dc | 204 | return swp_entry(type, offset); |
5d337b91 | 205 | } |
fb4f88dc | 206 | next = swap_list.next; |
1da177e4 | 207 | } |
fb4f88dc HD |
208 | |
209 | nr_swap_pages++; | |
210 | noswap: | |
5d337b91 | 211 | spin_unlock(&swap_lock); |
fb4f88dc | 212 | return (swp_entry_t) {0}; |
1da177e4 LT |
213 | } |
214 | ||
3a291a20 RW |
215 | swp_entry_t get_swap_page_of_type(int type) |
216 | { | |
217 | struct swap_info_struct *si; | |
218 | pgoff_t offset; | |
219 | ||
220 | spin_lock(&swap_lock); | |
221 | si = swap_info + type; | |
222 | if (si->flags & SWP_WRITEOK) { | |
223 | nr_swap_pages--; | |
224 | offset = scan_swap_map(si); | |
225 | if (offset) { | |
226 | spin_unlock(&swap_lock); | |
227 | return swp_entry(type, offset); | |
228 | } | |
229 | nr_swap_pages++; | |
230 | } | |
231 | spin_unlock(&swap_lock); | |
232 | return (swp_entry_t) {0}; | |
233 | } | |
234 | ||
1da177e4 LT |
235 | static struct swap_info_struct * swap_info_get(swp_entry_t entry) |
236 | { | |
237 | struct swap_info_struct * p; | |
238 | unsigned long offset, type; | |
239 | ||
240 | if (!entry.val) | |
241 | goto out; | |
242 | type = swp_type(entry); | |
243 | if (type >= nr_swapfiles) | |
244 | goto bad_nofile; | |
245 | p = & swap_info[type]; | |
246 | if (!(p->flags & SWP_USED)) | |
247 | goto bad_device; | |
248 | offset = swp_offset(entry); | |
249 | if (offset >= p->max) | |
250 | goto bad_offset; | |
251 | if (!p->swap_map[offset]) | |
252 | goto bad_free; | |
5d337b91 | 253 | spin_lock(&swap_lock); |
1da177e4 LT |
254 | return p; |
255 | ||
256 | bad_free: | |
257 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val); | |
258 | goto out; | |
259 | bad_offset: | |
260 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val); | |
261 | goto out; | |
262 | bad_device: | |
263 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val); | |
264 | goto out; | |
265 | bad_nofile: | |
266 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val); | |
267 | out: | |
268 | return NULL; | |
269 | } | |
270 | ||
1da177e4 LT |
271 | static int swap_entry_free(struct swap_info_struct *p, unsigned long offset) |
272 | { | |
273 | int count = p->swap_map[offset]; | |
274 | ||
275 | if (count < SWAP_MAP_MAX) { | |
276 | count--; | |
277 | p->swap_map[offset] = count; | |
278 | if (!count) { | |
279 | if (offset < p->lowest_bit) | |
280 | p->lowest_bit = offset; | |
281 | if (offset > p->highest_bit) | |
282 | p->highest_bit = offset; | |
89d09a2c HD |
283 | if (p->prio > swap_info[swap_list.next].prio) |
284 | swap_list.next = p - swap_info; | |
1da177e4 LT |
285 | nr_swap_pages++; |
286 | p->inuse_pages--; | |
287 | } | |
288 | } | |
289 | return count; | |
290 | } | |
291 | ||
292 | /* | |
293 | * Caller has made sure that the swapdevice corresponding to entry | |
294 | * is still around or has not been recycled. | |
295 | */ | |
296 | void swap_free(swp_entry_t entry) | |
297 | { | |
298 | struct swap_info_struct * p; | |
299 | ||
300 | p = swap_info_get(entry); | |
301 | if (p) { | |
302 | swap_entry_free(p, swp_offset(entry)); | |
5d337b91 | 303 | spin_unlock(&swap_lock); |
1da177e4 LT |
304 | } |
305 | } | |
306 | ||
307 | /* | |
c475a8ab | 308 | * How many references to page are currently swapped out? |
1da177e4 | 309 | */ |
c475a8ab | 310 | static inline int page_swapcount(struct page *page) |
1da177e4 | 311 | { |
c475a8ab HD |
312 | int count = 0; |
313 | struct swap_info_struct *p; | |
1da177e4 LT |
314 | swp_entry_t entry; |
315 | ||
4c21e2f2 | 316 | entry.val = page_private(page); |
1da177e4 LT |
317 | p = swap_info_get(entry); |
318 | if (p) { | |
c475a8ab HD |
319 | /* Subtract the 1 for the swap cache itself */ |
320 | count = p->swap_map[swp_offset(entry)] - 1; | |
5d337b91 | 321 | spin_unlock(&swap_lock); |
1da177e4 | 322 | } |
c475a8ab | 323 | return count; |
1da177e4 LT |
324 | } |
325 | ||
326 | /* | |
327 | * We can use this swap cache entry directly | |
328 | * if there are no other references to it. | |
1da177e4 LT |
329 | */ |
330 | int can_share_swap_page(struct page *page) | |
331 | { | |
c475a8ab HD |
332 | int count; |
333 | ||
334 | BUG_ON(!PageLocked(page)); | |
335 | count = page_mapcount(page); | |
336 | if (count <= 1 && PageSwapCache(page)) | |
337 | count += page_swapcount(page); | |
338 | return count == 1; | |
1da177e4 LT |
339 | } |
340 | ||
341 | /* | |
342 | * Work out if there are any other processes sharing this | |
343 | * swap cache page. Free it if you can. Return success. | |
344 | */ | |
345 | int remove_exclusive_swap_page(struct page *page) | |
346 | { | |
347 | int retval; | |
348 | struct swap_info_struct * p; | |
349 | swp_entry_t entry; | |
350 | ||
351 | BUG_ON(PagePrivate(page)); | |
352 | BUG_ON(!PageLocked(page)); | |
353 | ||
354 | if (!PageSwapCache(page)) | |
355 | return 0; | |
356 | if (PageWriteback(page)) | |
357 | return 0; | |
358 | if (page_count(page) != 2) /* 2: us + cache */ | |
359 | return 0; | |
360 | ||
4c21e2f2 | 361 | entry.val = page_private(page); |
1da177e4 LT |
362 | p = swap_info_get(entry); |
363 | if (!p) | |
364 | return 0; | |
365 | ||
366 | /* Is the only swap cache user the cache itself? */ | |
367 | retval = 0; | |
368 | if (p->swap_map[swp_offset(entry)] == 1) { | |
369 | /* Recheck the page count with the swapcache lock held.. */ | |
370 | write_lock_irq(&swapper_space.tree_lock); | |
371 | if ((page_count(page) == 2) && !PageWriteback(page)) { | |
372 | __delete_from_swap_cache(page); | |
373 | SetPageDirty(page); | |
374 | retval = 1; | |
375 | } | |
376 | write_unlock_irq(&swapper_space.tree_lock); | |
377 | } | |
5d337b91 | 378 | spin_unlock(&swap_lock); |
1da177e4 LT |
379 | |
380 | if (retval) { | |
381 | swap_free(entry); | |
382 | page_cache_release(page); | |
383 | } | |
384 | ||
385 | return retval; | |
386 | } | |
387 | ||
388 | /* | |
389 | * Free the swap entry like above, but also try to | |
390 | * free the page cache entry if it is the last user. | |
391 | */ | |
392 | void free_swap_and_cache(swp_entry_t entry) | |
393 | { | |
394 | struct swap_info_struct * p; | |
395 | struct page *page = NULL; | |
396 | ||
397 | p = swap_info_get(entry); | |
398 | if (p) { | |
399 | if (swap_entry_free(p, swp_offset(entry)) == 1) | |
400 | page = find_trylock_page(&swapper_space, entry.val); | |
5d337b91 | 401 | spin_unlock(&swap_lock); |
1da177e4 LT |
402 | } |
403 | if (page) { | |
404 | int one_user; | |
405 | ||
406 | BUG_ON(PagePrivate(page)); | |
407 | page_cache_get(page); | |
408 | one_user = (page_count(page) == 2); | |
409 | /* Only cache user (+us), or swap space full? Free it! */ | |
410 | if (!PageWriteback(page) && (one_user || vm_swap_full())) { | |
411 | delete_from_swap_cache(page); | |
412 | SetPageDirty(page); | |
413 | } | |
414 | unlock_page(page); | |
415 | page_cache_release(page); | |
416 | } | |
417 | } | |
418 | ||
419 | /* | |
72866f6f HD |
420 | * No need to decide whether this PTE shares the swap entry with others, |
421 | * just let do_wp_page work it out if a write is requested later - to | |
422 | * force COW, vm_page_prot omits write permission from any private vma. | |
1da177e4 LT |
423 | */ |
424 | static void unuse_pte(struct vm_area_struct *vma, pte_t *pte, | |
425 | unsigned long addr, swp_entry_t entry, struct page *page) | |
426 | { | |
4294621f | 427 | inc_mm_counter(vma->vm_mm, anon_rss); |
1da177e4 LT |
428 | get_page(page); |
429 | set_pte_at(vma->vm_mm, addr, pte, | |
430 | pte_mkold(mk_pte(page, vma->vm_page_prot))); | |
431 | page_add_anon_rmap(page, vma, addr); | |
432 | swap_free(entry); | |
433 | /* | |
434 | * Move the page to the active list so it is not | |
435 | * immediately swapped out again after swapon. | |
436 | */ | |
437 | activate_page(page); | |
438 | } | |
439 | ||
440 | static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, | |
441 | unsigned long addr, unsigned long end, | |
442 | swp_entry_t entry, struct page *page) | |
443 | { | |
1da177e4 | 444 | pte_t swp_pte = swp_entry_to_pte(entry); |
705e87c0 HD |
445 | pte_t *pte; |
446 | spinlock_t *ptl; | |
447 | int found = 0; | |
1da177e4 | 448 | |
705e87c0 | 449 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); |
1da177e4 LT |
450 | do { |
451 | /* | |
452 | * swapoff spends a _lot_ of time in this loop! | |
453 | * Test inline before going to call unuse_pte. | |
454 | */ | |
455 | if (unlikely(pte_same(*pte, swp_pte))) { | |
705e87c0 HD |
456 | unuse_pte(vma, pte++, addr, entry, page); |
457 | found = 1; | |
458 | break; | |
1da177e4 LT |
459 | } |
460 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
705e87c0 HD |
461 | pte_unmap_unlock(pte - 1, ptl); |
462 | return found; | |
1da177e4 LT |
463 | } |
464 | ||
465 | static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, | |
466 | unsigned long addr, unsigned long end, | |
467 | swp_entry_t entry, struct page *page) | |
468 | { | |
469 | pmd_t *pmd; | |
470 | unsigned long next; | |
471 | ||
472 | pmd = pmd_offset(pud, addr); | |
473 | do { | |
474 | next = pmd_addr_end(addr, end); | |
475 | if (pmd_none_or_clear_bad(pmd)) | |
476 | continue; | |
477 | if (unuse_pte_range(vma, pmd, addr, next, entry, page)) | |
478 | return 1; | |
479 | } while (pmd++, addr = next, addr != end); | |
480 | return 0; | |
481 | } | |
482 | ||
483 | static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd, | |
484 | unsigned long addr, unsigned long end, | |
485 | swp_entry_t entry, struct page *page) | |
486 | { | |
487 | pud_t *pud; | |
488 | unsigned long next; | |
489 | ||
490 | pud = pud_offset(pgd, addr); | |
491 | do { | |
492 | next = pud_addr_end(addr, end); | |
493 | if (pud_none_or_clear_bad(pud)) | |
494 | continue; | |
495 | if (unuse_pmd_range(vma, pud, addr, next, entry, page)) | |
496 | return 1; | |
497 | } while (pud++, addr = next, addr != end); | |
498 | return 0; | |
499 | } | |
500 | ||
501 | static int unuse_vma(struct vm_area_struct *vma, | |
502 | swp_entry_t entry, struct page *page) | |
503 | { | |
504 | pgd_t *pgd; | |
505 | unsigned long addr, end, next; | |
506 | ||
507 | if (page->mapping) { | |
508 | addr = page_address_in_vma(page, vma); | |
509 | if (addr == -EFAULT) | |
510 | return 0; | |
511 | else | |
512 | end = addr + PAGE_SIZE; | |
513 | } else { | |
514 | addr = vma->vm_start; | |
515 | end = vma->vm_end; | |
516 | } | |
517 | ||
518 | pgd = pgd_offset(vma->vm_mm, addr); | |
519 | do { | |
520 | next = pgd_addr_end(addr, end); | |
521 | if (pgd_none_or_clear_bad(pgd)) | |
522 | continue; | |
523 | if (unuse_pud_range(vma, pgd, addr, next, entry, page)) | |
524 | return 1; | |
525 | } while (pgd++, addr = next, addr != end); | |
526 | return 0; | |
527 | } | |
528 | ||
529 | static int unuse_mm(struct mm_struct *mm, | |
530 | swp_entry_t entry, struct page *page) | |
531 | { | |
532 | struct vm_area_struct *vma; | |
533 | ||
534 | if (!down_read_trylock(&mm->mmap_sem)) { | |
535 | /* | |
c475a8ab HD |
536 | * Activate page so shrink_cache is unlikely to unmap its |
537 | * ptes while lock is dropped, so swapoff can make progress. | |
1da177e4 | 538 | */ |
c475a8ab | 539 | activate_page(page); |
1da177e4 LT |
540 | unlock_page(page); |
541 | down_read(&mm->mmap_sem); | |
542 | lock_page(page); | |
543 | } | |
1da177e4 LT |
544 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
545 | if (vma->anon_vma && unuse_vma(vma, entry, page)) | |
546 | break; | |
547 | } | |
1da177e4 LT |
548 | up_read(&mm->mmap_sem); |
549 | /* | |
550 | * Currently unuse_mm cannot fail, but leave error handling | |
551 | * at call sites for now, since we change it from time to time. | |
552 | */ | |
553 | return 0; | |
554 | } | |
555 | ||
556 | /* | |
557 | * Scan swap_map from current position to next entry still in use. | |
558 | * Recycle to start on reaching the end, returning 0 when empty. | |
559 | */ | |
6eb396dc HD |
560 | static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
561 | unsigned int prev) | |
1da177e4 | 562 | { |
6eb396dc HD |
563 | unsigned int max = si->max; |
564 | unsigned int i = prev; | |
1da177e4 LT |
565 | int count; |
566 | ||
567 | /* | |
5d337b91 | 568 | * No need for swap_lock here: we're just looking |
1da177e4 LT |
569 | * for whether an entry is in use, not modifying it; false |
570 | * hits are okay, and sys_swapoff() has already prevented new | |
5d337b91 | 571 | * allocations from this area (while holding swap_lock). |
1da177e4 LT |
572 | */ |
573 | for (;;) { | |
574 | if (++i >= max) { | |
575 | if (!prev) { | |
576 | i = 0; | |
577 | break; | |
578 | } | |
579 | /* | |
580 | * No entries in use at top of swap_map, | |
581 | * loop back to start and recheck there. | |
582 | */ | |
583 | max = prev + 1; | |
584 | prev = 0; | |
585 | i = 1; | |
586 | } | |
587 | count = si->swap_map[i]; | |
588 | if (count && count != SWAP_MAP_BAD) | |
589 | break; | |
590 | } | |
591 | return i; | |
592 | } | |
593 | ||
594 | /* | |
595 | * We completely avoid races by reading each swap page in advance, | |
596 | * and then search for the process using it. All the necessary | |
597 | * page table adjustments can then be made atomically. | |
598 | */ | |
599 | static int try_to_unuse(unsigned int type) | |
600 | { | |
601 | struct swap_info_struct * si = &swap_info[type]; | |
602 | struct mm_struct *start_mm; | |
603 | unsigned short *swap_map; | |
604 | unsigned short swcount; | |
605 | struct page *page; | |
606 | swp_entry_t entry; | |
6eb396dc | 607 | unsigned int i = 0; |
1da177e4 LT |
608 | int retval = 0; |
609 | int reset_overflow = 0; | |
610 | int shmem; | |
611 | ||
612 | /* | |
613 | * When searching mms for an entry, a good strategy is to | |
614 | * start at the first mm we freed the previous entry from | |
615 | * (though actually we don't notice whether we or coincidence | |
616 | * freed the entry). Initialize this start_mm with a hold. | |
617 | * | |
618 | * A simpler strategy would be to start at the last mm we | |
619 | * freed the previous entry from; but that would take less | |
620 | * advantage of mmlist ordering, which clusters forked mms | |
621 | * together, child after parent. If we race with dup_mmap(), we | |
622 | * prefer to resolve parent before child, lest we miss entries | |
623 | * duplicated after we scanned child: using last mm would invert | |
624 | * that. Though it's only a serious concern when an overflowed | |
625 | * swap count is reset from SWAP_MAP_MAX, preventing a rescan. | |
626 | */ | |
627 | start_mm = &init_mm; | |
628 | atomic_inc(&init_mm.mm_users); | |
629 | ||
630 | /* | |
631 | * Keep on scanning until all entries have gone. Usually, | |
632 | * one pass through swap_map is enough, but not necessarily: | |
633 | * there are races when an instance of an entry might be missed. | |
634 | */ | |
635 | while ((i = find_next_to_unuse(si, i)) != 0) { | |
636 | if (signal_pending(current)) { | |
637 | retval = -EINTR; | |
638 | break; | |
639 | } | |
640 | ||
641 | /* | |
642 | * Get a page for the entry, using the existing swap | |
643 | * cache page if there is one. Otherwise, get a clean | |
644 | * page and read the swap into it. | |
645 | */ | |
646 | swap_map = &si->swap_map[i]; | |
647 | entry = swp_entry(type, i); | |
648 | page = read_swap_cache_async(entry, NULL, 0); | |
649 | if (!page) { | |
650 | /* | |
651 | * Either swap_duplicate() failed because entry | |
652 | * has been freed independently, and will not be | |
653 | * reused since sys_swapoff() already disabled | |
654 | * allocation from here, or alloc_page() failed. | |
655 | */ | |
656 | if (!*swap_map) | |
657 | continue; | |
658 | retval = -ENOMEM; | |
659 | break; | |
660 | } | |
661 | ||
662 | /* | |
663 | * Don't hold on to start_mm if it looks like exiting. | |
664 | */ | |
665 | if (atomic_read(&start_mm->mm_users) == 1) { | |
666 | mmput(start_mm); | |
667 | start_mm = &init_mm; | |
668 | atomic_inc(&init_mm.mm_users); | |
669 | } | |
670 | ||
671 | /* | |
672 | * Wait for and lock page. When do_swap_page races with | |
673 | * try_to_unuse, do_swap_page can handle the fault much | |
674 | * faster than try_to_unuse can locate the entry. This | |
675 | * apparently redundant "wait_on_page_locked" lets try_to_unuse | |
676 | * defer to do_swap_page in such a case - in some tests, | |
677 | * do_swap_page and try_to_unuse repeatedly compete. | |
678 | */ | |
679 | wait_on_page_locked(page); | |
680 | wait_on_page_writeback(page); | |
681 | lock_page(page); | |
682 | wait_on_page_writeback(page); | |
683 | ||
684 | /* | |
685 | * Remove all references to entry. | |
686 | * Whenever we reach init_mm, there's no address space | |
687 | * to search, but use it as a reminder to search shmem. | |
688 | */ | |
689 | shmem = 0; | |
690 | swcount = *swap_map; | |
691 | if (swcount > 1) { | |
692 | if (start_mm == &init_mm) | |
693 | shmem = shmem_unuse(entry, page); | |
694 | else | |
695 | retval = unuse_mm(start_mm, entry, page); | |
696 | } | |
697 | if (*swap_map > 1) { | |
698 | int set_start_mm = (*swap_map >= swcount); | |
699 | struct list_head *p = &start_mm->mmlist; | |
700 | struct mm_struct *new_start_mm = start_mm; | |
701 | struct mm_struct *prev_mm = start_mm; | |
702 | struct mm_struct *mm; | |
703 | ||
704 | atomic_inc(&new_start_mm->mm_users); | |
705 | atomic_inc(&prev_mm->mm_users); | |
706 | spin_lock(&mmlist_lock); | |
707 | while (*swap_map > 1 && !retval && | |
708 | (p = p->next) != &start_mm->mmlist) { | |
709 | mm = list_entry(p, struct mm_struct, mmlist); | |
710 | if (atomic_inc_return(&mm->mm_users) == 1) { | |
711 | atomic_dec(&mm->mm_users); | |
712 | continue; | |
713 | } | |
714 | spin_unlock(&mmlist_lock); | |
715 | mmput(prev_mm); | |
716 | prev_mm = mm; | |
717 | ||
718 | cond_resched(); | |
719 | ||
720 | swcount = *swap_map; | |
721 | if (swcount <= 1) | |
722 | ; | |
723 | else if (mm == &init_mm) { | |
724 | set_start_mm = 1; | |
725 | shmem = shmem_unuse(entry, page); | |
726 | } else | |
727 | retval = unuse_mm(mm, entry, page); | |
728 | if (set_start_mm && *swap_map < swcount) { | |
729 | mmput(new_start_mm); | |
730 | atomic_inc(&mm->mm_users); | |
731 | new_start_mm = mm; | |
732 | set_start_mm = 0; | |
733 | } | |
734 | spin_lock(&mmlist_lock); | |
735 | } | |
736 | spin_unlock(&mmlist_lock); | |
737 | mmput(prev_mm); | |
738 | mmput(start_mm); | |
739 | start_mm = new_start_mm; | |
740 | } | |
741 | if (retval) { | |
742 | unlock_page(page); | |
743 | page_cache_release(page); | |
744 | break; | |
745 | } | |
746 | ||
747 | /* | |
748 | * How could swap count reach 0x7fff when the maximum | |
749 | * pid is 0x7fff, and there's no way to repeat a swap | |
750 | * page within an mm (except in shmem, where it's the | |
751 | * shared object which takes the reference count)? | |
752 | * We believe SWAP_MAP_MAX cannot occur in Linux 2.4. | |
753 | * | |
754 | * If that's wrong, then we should worry more about | |
755 | * exit_mmap() and do_munmap() cases described above: | |
756 | * we might be resetting SWAP_MAP_MAX too early here. | |
757 | * We know "Undead"s can happen, they're okay, so don't | |
758 | * report them; but do report if we reset SWAP_MAP_MAX. | |
759 | */ | |
760 | if (*swap_map == SWAP_MAP_MAX) { | |
5d337b91 | 761 | spin_lock(&swap_lock); |
1da177e4 | 762 | *swap_map = 1; |
5d337b91 | 763 | spin_unlock(&swap_lock); |
1da177e4 LT |
764 | reset_overflow = 1; |
765 | } | |
766 | ||
767 | /* | |
768 | * If a reference remains (rare), we would like to leave | |
769 | * the page in the swap cache; but try_to_unmap could | |
770 | * then re-duplicate the entry once we drop page lock, | |
771 | * so we might loop indefinitely; also, that page could | |
772 | * not be swapped out to other storage meanwhile. So: | |
773 | * delete from cache even if there's another reference, | |
774 | * after ensuring that the data has been saved to disk - | |
775 | * since if the reference remains (rarer), it will be | |
776 | * read from disk into another page. Splitting into two | |
777 | * pages would be incorrect if swap supported "shared | |
778 | * private" pages, but they are handled by tmpfs files. | |
779 | * | |
780 | * Note shmem_unuse already deleted a swappage from | |
781 | * the swap cache, unless the move to filepage failed: | |
782 | * in which case it left swappage in cache, lowered its | |
783 | * swap count to pass quickly through the loops above, | |
784 | * and now we must reincrement count to try again later. | |
785 | */ | |
786 | if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) { | |
787 | struct writeback_control wbc = { | |
788 | .sync_mode = WB_SYNC_NONE, | |
789 | }; | |
790 | ||
791 | swap_writepage(page, &wbc); | |
792 | lock_page(page); | |
793 | wait_on_page_writeback(page); | |
794 | } | |
795 | if (PageSwapCache(page)) { | |
796 | if (shmem) | |
797 | swap_duplicate(entry); | |
798 | else | |
799 | delete_from_swap_cache(page); | |
800 | } | |
801 | ||
802 | /* | |
803 | * So we could skip searching mms once swap count went | |
804 | * to 1, we did not mark any present ptes as dirty: must | |
805 | * mark page dirty so shrink_list will preserve it. | |
806 | */ | |
807 | SetPageDirty(page); | |
808 | unlock_page(page); | |
809 | page_cache_release(page); | |
810 | ||
811 | /* | |
812 | * Make sure that we aren't completely killing | |
813 | * interactive performance. | |
814 | */ | |
815 | cond_resched(); | |
816 | } | |
817 | ||
818 | mmput(start_mm); | |
819 | if (reset_overflow) { | |
820 | printk(KERN_WARNING "swapoff: cleared swap entry overflow\n"); | |
821 | swap_overflow = 0; | |
822 | } | |
823 | return retval; | |
824 | } | |
825 | ||
826 | /* | |
5d337b91 HD |
827 | * After a successful try_to_unuse, if no swap is now in use, we know |
828 | * we can empty the mmlist. swap_lock must be held on entry and exit. | |
829 | * Note that mmlist_lock nests inside swap_lock, and an mm must be | |
1da177e4 LT |
830 | * added to the mmlist just after page_duplicate - before would be racy. |
831 | */ | |
832 | static void drain_mmlist(void) | |
833 | { | |
834 | struct list_head *p, *next; | |
835 | unsigned int i; | |
836 | ||
837 | for (i = 0; i < nr_swapfiles; i++) | |
838 | if (swap_info[i].inuse_pages) | |
839 | return; | |
840 | spin_lock(&mmlist_lock); | |
841 | list_for_each_safe(p, next, &init_mm.mmlist) | |
842 | list_del_init(p); | |
843 | spin_unlock(&mmlist_lock); | |
844 | } | |
845 | ||
846 | /* | |
847 | * Use this swapdev's extent info to locate the (PAGE_SIZE) block which | |
848 | * corresponds to page offset `offset'. | |
849 | */ | |
850 | sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset) | |
851 | { | |
852 | struct swap_extent *se = sis->curr_swap_extent; | |
853 | struct swap_extent *start_se = se; | |
854 | ||
855 | for ( ; ; ) { | |
856 | struct list_head *lh; | |
857 | ||
858 | if (se->start_page <= offset && | |
859 | offset < (se->start_page + se->nr_pages)) { | |
860 | return se->start_block + (offset - se->start_page); | |
861 | } | |
11d31886 | 862 | lh = se->list.next; |
1da177e4 | 863 | if (lh == &sis->extent_list) |
11d31886 | 864 | lh = lh->next; |
1da177e4 LT |
865 | se = list_entry(lh, struct swap_extent, list); |
866 | sis->curr_swap_extent = se; | |
867 | BUG_ON(se == start_se); /* It *must* be present */ | |
868 | } | |
869 | } | |
870 | ||
871 | /* | |
872 | * Free all of a swapdev's extent information | |
873 | */ | |
874 | static void destroy_swap_extents(struct swap_info_struct *sis) | |
875 | { | |
876 | while (!list_empty(&sis->extent_list)) { | |
877 | struct swap_extent *se; | |
878 | ||
879 | se = list_entry(sis->extent_list.next, | |
880 | struct swap_extent, list); | |
881 | list_del(&se->list); | |
882 | kfree(se); | |
883 | } | |
1da177e4 LT |
884 | } |
885 | ||
886 | /* | |
887 | * Add a block range (and the corresponding page range) into this swapdev's | |
11d31886 | 888 | * extent list. The extent list is kept sorted in page order. |
1da177e4 | 889 | * |
11d31886 | 890 | * This function rather assumes that it is called in ascending page order. |
1da177e4 LT |
891 | */ |
892 | static int | |
893 | add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, | |
894 | unsigned long nr_pages, sector_t start_block) | |
895 | { | |
896 | struct swap_extent *se; | |
897 | struct swap_extent *new_se; | |
898 | struct list_head *lh; | |
899 | ||
11d31886 HD |
900 | lh = sis->extent_list.prev; /* The highest page extent */ |
901 | if (lh != &sis->extent_list) { | |
1da177e4 | 902 | se = list_entry(lh, struct swap_extent, list); |
11d31886 HD |
903 | BUG_ON(se->start_page + se->nr_pages != start_page); |
904 | if (se->start_block + se->nr_pages == start_block) { | |
1da177e4 LT |
905 | /* Merge it */ |
906 | se->nr_pages += nr_pages; | |
907 | return 0; | |
908 | } | |
1da177e4 LT |
909 | } |
910 | ||
911 | /* | |
912 | * No merge. Insert a new extent, preserving ordering. | |
913 | */ | |
914 | new_se = kmalloc(sizeof(*se), GFP_KERNEL); | |
915 | if (new_se == NULL) | |
916 | return -ENOMEM; | |
917 | new_se->start_page = start_page; | |
918 | new_se->nr_pages = nr_pages; | |
919 | new_se->start_block = start_block; | |
920 | ||
11d31886 | 921 | list_add_tail(&new_se->list, &sis->extent_list); |
53092a74 | 922 | return 1; |
1da177e4 LT |
923 | } |
924 | ||
925 | /* | |
926 | * A `swap extent' is a simple thing which maps a contiguous range of pages | |
927 | * onto a contiguous range of disk blocks. An ordered list of swap extents | |
928 | * is built at swapon time and is then used at swap_writepage/swap_readpage | |
929 | * time for locating where on disk a page belongs. | |
930 | * | |
931 | * If the swapfile is an S_ISBLK block device, a single extent is installed. | |
932 | * This is done so that the main operating code can treat S_ISBLK and S_ISREG | |
933 | * swap files identically. | |
934 | * | |
935 | * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap | |
936 | * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK | |
937 | * swapfiles are handled *identically* after swapon time. | |
938 | * | |
939 | * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks | |
940 | * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If | |
941 | * some stray blocks are found which do not fall within the PAGE_SIZE alignment | |
942 | * requirements, they are simply tossed out - we will never use those blocks | |
943 | * for swapping. | |
944 | * | |
b0d9bcd4 | 945 | * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This |
1da177e4 LT |
946 | * prevents root from shooting her foot off by ftruncating an in-use swapfile, |
947 | * which will scribble on the fs. | |
948 | * | |
949 | * The amount of disk space which a single swap extent represents varies. | |
950 | * Typically it is in the 1-4 megabyte range. So we can have hundreds of | |
951 | * extents in the list. To avoid much list walking, we cache the previous | |
952 | * search location in `curr_swap_extent', and start new searches from there. | |
953 | * This is extremely effective. The average number of iterations in | |
954 | * map_swap_page() has been measured at about 0.3 per page. - akpm. | |
955 | */ | |
53092a74 | 956 | static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
1da177e4 LT |
957 | { |
958 | struct inode *inode; | |
959 | unsigned blocks_per_page; | |
960 | unsigned long page_no; | |
961 | unsigned blkbits; | |
962 | sector_t probe_block; | |
963 | sector_t last_block; | |
53092a74 HD |
964 | sector_t lowest_block = -1; |
965 | sector_t highest_block = 0; | |
966 | int nr_extents = 0; | |
1da177e4 LT |
967 | int ret; |
968 | ||
969 | inode = sis->swap_file->f_mapping->host; | |
970 | if (S_ISBLK(inode->i_mode)) { | |
971 | ret = add_swap_extent(sis, 0, sis->max, 0); | |
53092a74 | 972 | *span = sis->pages; |
1da177e4 LT |
973 | goto done; |
974 | } | |
975 | ||
976 | blkbits = inode->i_blkbits; | |
977 | blocks_per_page = PAGE_SIZE >> blkbits; | |
978 | ||
979 | /* | |
980 | * Map all the blocks into the extent list. This code doesn't try | |
981 | * to be very smart. | |
982 | */ | |
983 | probe_block = 0; | |
984 | page_no = 0; | |
985 | last_block = i_size_read(inode) >> blkbits; | |
986 | while ((probe_block + blocks_per_page) <= last_block && | |
987 | page_no < sis->max) { | |
988 | unsigned block_in_page; | |
989 | sector_t first_block; | |
990 | ||
991 | first_block = bmap(inode, probe_block); | |
992 | if (first_block == 0) | |
993 | goto bad_bmap; | |
994 | ||
995 | /* | |
996 | * It must be PAGE_SIZE aligned on-disk | |
997 | */ | |
998 | if (first_block & (blocks_per_page - 1)) { | |
999 | probe_block++; | |
1000 | goto reprobe; | |
1001 | } | |
1002 | ||
1003 | for (block_in_page = 1; block_in_page < blocks_per_page; | |
1004 | block_in_page++) { | |
1005 | sector_t block; | |
1006 | ||
1007 | block = bmap(inode, probe_block + block_in_page); | |
1008 | if (block == 0) | |
1009 | goto bad_bmap; | |
1010 | if (block != first_block + block_in_page) { | |
1011 | /* Discontiguity */ | |
1012 | probe_block++; | |
1013 | goto reprobe; | |
1014 | } | |
1015 | } | |
1016 | ||
53092a74 HD |
1017 | first_block >>= (PAGE_SHIFT - blkbits); |
1018 | if (page_no) { /* exclude the header page */ | |
1019 | if (first_block < lowest_block) | |
1020 | lowest_block = first_block; | |
1021 | if (first_block > highest_block) | |
1022 | highest_block = first_block; | |
1023 | } | |
1024 | ||
1da177e4 LT |
1025 | /* |
1026 | * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks | |
1027 | */ | |
53092a74 HD |
1028 | ret = add_swap_extent(sis, page_no, 1, first_block); |
1029 | if (ret < 0) | |
1da177e4 | 1030 | goto out; |
53092a74 | 1031 | nr_extents += ret; |
1da177e4 LT |
1032 | page_no++; |
1033 | probe_block += blocks_per_page; | |
1034 | reprobe: | |
1035 | continue; | |
1036 | } | |
53092a74 HD |
1037 | ret = nr_extents; |
1038 | *span = 1 + highest_block - lowest_block; | |
1da177e4 | 1039 | if (page_no == 0) |
e2244ec2 | 1040 | page_no = 1; /* force Empty message */ |
1da177e4 | 1041 | sis->max = page_no; |
e2244ec2 | 1042 | sis->pages = page_no - 1; |
1da177e4 LT |
1043 | sis->highest_bit = page_no - 1; |
1044 | done: | |
1045 | sis->curr_swap_extent = list_entry(sis->extent_list.prev, | |
1046 | struct swap_extent, list); | |
1047 | goto out; | |
1048 | bad_bmap: | |
1049 | printk(KERN_ERR "swapon: swapfile has holes\n"); | |
1050 | ret = -EINVAL; | |
1051 | out: | |
1052 | return ret; | |
1053 | } | |
1054 | ||
1055 | #if 0 /* We don't need this yet */ | |
1056 | #include <linux/backing-dev.h> | |
1057 | int page_queue_congested(struct page *page) | |
1058 | { | |
1059 | struct backing_dev_info *bdi; | |
1060 | ||
1061 | BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */ | |
1062 | ||
1063 | if (PageSwapCache(page)) { | |
4c21e2f2 | 1064 | swp_entry_t entry = { .val = page_private(page) }; |
1da177e4 LT |
1065 | struct swap_info_struct *sis; |
1066 | ||
1067 | sis = get_swap_info_struct(swp_type(entry)); | |
1068 | bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info; | |
1069 | } else | |
1070 | bdi = page->mapping->backing_dev_info; | |
1071 | return bdi_write_congested(bdi); | |
1072 | } | |
1073 | #endif | |
1074 | ||
1075 | asmlinkage long sys_swapoff(const char __user * specialfile) | |
1076 | { | |
1077 | struct swap_info_struct * p = NULL; | |
1078 | unsigned short *swap_map; | |
1079 | struct file *swap_file, *victim; | |
1080 | struct address_space *mapping; | |
1081 | struct inode *inode; | |
1082 | char * pathname; | |
1083 | int i, type, prev; | |
1084 | int err; | |
1085 | ||
1086 | if (!capable(CAP_SYS_ADMIN)) | |
1087 | return -EPERM; | |
1088 | ||
1089 | pathname = getname(specialfile); | |
1090 | err = PTR_ERR(pathname); | |
1091 | if (IS_ERR(pathname)) | |
1092 | goto out; | |
1093 | ||
1094 | victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0); | |
1095 | putname(pathname); | |
1096 | err = PTR_ERR(victim); | |
1097 | if (IS_ERR(victim)) | |
1098 | goto out; | |
1099 | ||
1100 | mapping = victim->f_mapping; | |
1101 | prev = -1; | |
5d337b91 | 1102 | spin_lock(&swap_lock); |
1da177e4 LT |
1103 | for (type = swap_list.head; type >= 0; type = swap_info[type].next) { |
1104 | p = swap_info + type; | |
1105 | if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) { | |
1106 | if (p->swap_file->f_mapping == mapping) | |
1107 | break; | |
1108 | } | |
1109 | prev = type; | |
1110 | } | |
1111 | if (type < 0) { | |
1112 | err = -EINVAL; | |
5d337b91 | 1113 | spin_unlock(&swap_lock); |
1da177e4 LT |
1114 | goto out_dput; |
1115 | } | |
1116 | if (!security_vm_enough_memory(p->pages)) | |
1117 | vm_unacct_memory(p->pages); | |
1118 | else { | |
1119 | err = -ENOMEM; | |
5d337b91 | 1120 | spin_unlock(&swap_lock); |
1da177e4 LT |
1121 | goto out_dput; |
1122 | } | |
1123 | if (prev < 0) { | |
1124 | swap_list.head = p->next; | |
1125 | } else { | |
1126 | swap_info[prev].next = p->next; | |
1127 | } | |
1128 | if (type == swap_list.next) { | |
1129 | /* just pick something that's safe... */ | |
1130 | swap_list.next = swap_list.head; | |
1131 | } | |
1132 | nr_swap_pages -= p->pages; | |
1133 | total_swap_pages -= p->pages; | |
1134 | p->flags &= ~SWP_WRITEOK; | |
5d337b91 | 1135 | spin_unlock(&swap_lock); |
fb4f88dc | 1136 | |
1da177e4 LT |
1137 | current->flags |= PF_SWAPOFF; |
1138 | err = try_to_unuse(type); | |
1139 | current->flags &= ~PF_SWAPOFF; | |
1140 | ||
1da177e4 LT |
1141 | if (err) { |
1142 | /* re-insert swap space back into swap_list */ | |
5d337b91 | 1143 | spin_lock(&swap_lock); |
1da177e4 LT |
1144 | for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next) |
1145 | if (p->prio >= swap_info[i].prio) | |
1146 | break; | |
1147 | p->next = i; | |
1148 | if (prev < 0) | |
1149 | swap_list.head = swap_list.next = p - swap_info; | |
1150 | else | |
1151 | swap_info[prev].next = p - swap_info; | |
1152 | nr_swap_pages += p->pages; | |
1153 | total_swap_pages += p->pages; | |
1154 | p->flags |= SWP_WRITEOK; | |
5d337b91 | 1155 | spin_unlock(&swap_lock); |
1da177e4 LT |
1156 | goto out_dput; |
1157 | } | |
52b7efdb HD |
1158 | |
1159 | /* wait for any unplug function to finish */ | |
1160 | down_write(&swap_unplug_sem); | |
1161 | up_write(&swap_unplug_sem); | |
1162 | ||
5d337b91 HD |
1163 | destroy_swap_extents(p); |
1164 | down(&swapon_sem); | |
1165 | spin_lock(&swap_lock); | |
1166 | drain_mmlist(); | |
1167 | ||
52b7efdb | 1168 | /* wait for anyone still in scan_swap_map */ |
52b7efdb HD |
1169 | p->highest_bit = 0; /* cuts scans short */ |
1170 | while (p->flags >= SWP_SCANNING) { | |
5d337b91 | 1171 | spin_unlock(&swap_lock); |
13e4b57f | 1172 | schedule_timeout_uninterruptible(1); |
5d337b91 | 1173 | spin_lock(&swap_lock); |
52b7efdb | 1174 | } |
52b7efdb | 1175 | |
1da177e4 LT |
1176 | swap_file = p->swap_file; |
1177 | p->swap_file = NULL; | |
1178 | p->max = 0; | |
1179 | swap_map = p->swap_map; | |
1180 | p->swap_map = NULL; | |
1181 | p->flags = 0; | |
5d337b91 | 1182 | spin_unlock(&swap_lock); |
1da177e4 LT |
1183 | up(&swapon_sem); |
1184 | vfree(swap_map); | |
1185 | inode = mapping->host; | |
1186 | if (S_ISBLK(inode->i_mode)) { | |
1187 | struct block_device *bdev = I_BDEV(inode); | |
1188 | set_blocksize(bdev, p->old_block_size); | |
1189 | bd_release(bdev); | |
1190 | } else { | |
1b1dcc1b | 1191 | mutex_lock(&inode->i_mutex); |
1da177e4 | 1192 | inode->i_flags &= ~S_SWAPFILE; |
1b1dcc1b | 1193 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
1194 | } |
1195 | filp_close(swap_file, NULL); | |
1196 | err = 0; | |
1197 | ||
1198 | out_dput: | |
1199 | filp_close(victim, NULL); | |
1200 | out: | |
1201 | return err; | |
1202 | } | |
1203 | ||
1204 | #ifdef CONFIG_PROC_FS | |
1205 | /* iterator */ | |
1206 | static void *swap_start(struct seq_file *swap, loff_t *pos) | |
1207 | { | |
1208 | struct swap_info_struct *ptr = swap_info; | |
1209 | int i; | |
1210 | loff_t l = *pos; | |
1211 | ||
1212 | down(&swapon_sem); | |
1213 | ||
1214 | for (i = 0; i < nr_swapfiles; i++, ptr++) { | |
1215 | if (!(ptr->flags & SWP_USED) || !ptr->swap_map) | |
1216 | continue; | |
1217 | if (!l--) | |
1218 | return ptr; | |
1219 | } | |
1220 | ||
1221 | return NULL; | |
1222 | } | |
1223 | ||
1224 | static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) | |
1225 | { | |
1226 | struct swap_info_struct *ptr = v; | |
1227 | struct swap_info_struct *endptr = swap_info + nr_swapfiles; | |
1228 | ||
1229 | for (++ptr; ptr < endptr; ptr++) { | |
1230 | if (!(ptr->flags & SWP_USED) || !ptr->swap_map) | |
1231 | continue; | |
1232 | ++*pos; | |
1233 | return ptr; | |
1234 | } | |
1235 | ||
1236 | return NULL; | |
1237 | } | |
1238 | ||
1239 | static void swap_stop(struct seq_file *swap, void *v) | |
1240 | { | |
1241 | up(&swapon_sem); | |
1242 | } | |
1243 | ||
1244 | static int swap_show(struct seq_file *swap, void *v) | |
1245 | { | |
1246 | struct swap_info_struct *ptr = v; | |
1247 | struct file *file; | |
1248 | int len; | |
1249 | ||
1250 | if (v == swap_info) | |
1251 | seq_puts(swap, "Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n"); | |
1252 | ||
1253 | file = ptr->swap_file; | |
1254 | len = seq_path(swap, file->f_vfsmnt, file->f_dentry, " \t\n\\"); | |
6eb396dc | 1255 | seq_printf(swap, "%*s%s\t%u\t%u\t%d\n", |
1da177e4 LT |
1256 | len < 40 ? 40 - len : 1, " ", |
1257 | S_ISBLK(file->f_dentry->d_inode->i_mode) ? | |
1258 | "partition" : "file\t", | |
1259 | ptr->pages << (PAGE_SHIFT - 10), | |
1260 | ptr->inuse_pages << (PAGE_SHIFT - 10), | |
1261 | ptr->prio); | |
1262 | return 0; | |
1263 | } | |
1264 | ||
1265 | static struct seq_operations swaps_op = { | |
1266 | .start = swap_start, | |
1267 | .next = swap_next, | |
1268 | .stop = swap_stop, | |
1269 | .show = swap_show | |
1270 | }; | |
1271 | ||
1272 | static int swaps_open(struct inode *inode, struct file *file) | |
1273 | { | |
1274 | return seq_open(file, &swaps_op); | |
1275 | } | |
1276 | ||
1277 | static struct file_operations proc_swaps_operations = { | |
1278 | .open = swaps_open, | |
1279 | .read = seq_read, | |
1280 | .llseek = seq_lseek, | |
1281 | .release = seq_release, | |
1282 | }; | |
1283 | ||
1284 | static int __init procswaps_init(void) | |
1285 | { | |
1286 | struct proc_dir_entry *entry; | |
1287 | ||
1288 | entry = create_proc_entry("swaps", 0, NULL); | |
1289 | if (entry) | |
1290 | entry->proc_fops = &proc_swaps_operations; | |
1291 | return 0; | |
1292 | } | |
1293 | __initcall(procswaps_init); | |
1294 | #endif /* CONFIG_PROC_FS */ | |
1295 | ||
1296 | /* | |
1297 | * Written 01/25/92 by Simmule Turner, heavily changed by Linus. | |
1298 | * | |
1299 | * The swapon system call | |
1300 | */ | |
1301 | asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags) | |
1302 | { | |
1303 | struct swap_info_struct * p; | |
1304 | char *name = NULL; | |
1305 | struct block_device *bdev = NULL; | |
1306 | struct file *swap_file = NULL; | |
1307 | struct address_space *mapping; | |
1308 | unsigned int type; | |
1309 | int i, prev; | |
1310 | int error; | |
1311 | static int least_priority; | |
1312 | union swap_header *swap_header = NULL; | |
1313 | int swap_header_version; | |
6eb396dc HD |
1314 | unsigned int nr_good_pages = 0; |
1315 | int nr_extents = 0; | |
53092a74 | 1316 | sector_t span; |
1da177e4 LT |
1317 | unsigned long maxpages = 1; |
1318 | int swapfilesize; | |
1319 | unsigned short *swap_map; | |
1320 | struct page *page = NULL; | |
1321 | struct inode *inode = NULL; | |
1322 | int did_down = 0; | |
1323 | ||
1324 | if (!capable(CAP_SYS_ADMIN)) | |
1325 | return -EPERM; | |
5d337b91 | 1326 | spin_lock(&swap_lock); |
1da177e4 LT |
1327 | p = swap_info; |
1328 | for (type = 0 ; type < nr_swapfiles ; type++,p++) | |
1329 | if (!(p->flags & SWP_USED)) | |
1330 | break; | |
1331 | error = -EPERM; | |
1332 | /* | |
1333 | * Test if adding another swap device is possible. There are | |
1334 | * two limiting factors: 1) the number of bits for the swap | |
1335 | * type swp_entry_t definition and 2) the number of bits for | |
1336 | * the swap type in the swap ptes as defined by the different | |
1337 | * architectures. To honor both limitations a swap entry | |
1338 | * with swap offset 0 and swap type ~0UL is created, encoded | |
1339 | * to a swap pte, decoded to a swp_entry_t again and finally | |
1340 | * the swap type part is extracted. This will mask all bits | |
1341 | * from the initial ~0UL that can't be encoded in either the | |
1342 | * swp_entry_t or the architecture definition of a swap pte. | |
1343 | */ | |
1344 | if (type > swp_type(pte_to_swp_entry(swp_entry_to_pte(swp_entry(~0UL,0))))) { | |
5d337b91 | 1345 | spin_unlock(&swap_lock); |
1da177e4 LT |
1346 | goto out; |
1347 | } | |
1348 | if (type >= nr_swapfiles) | |
1349 | nr_swapfiles = type+1; | |
1350 | INIT_LIST_HEAD(&p->extent_list); | |
1351 | p->flags = SWP_USED; | |
1da177e4 LT |
1352 | p->swap_file = NULL; |
1353 | p->old_block_size = 0; | |
1354 | p->swap_map = NULL; | |
1355 | p->lowest_bit = 0; | |
1356 | p->highest_bit = 0; | |
1357 | p->cluster_nr = 0; | |
1358 | p->inuse_pages = 0; | |
1da177e4 LT |
1359 | p->next = -1; |
1360 | if (swap_flags & SWAP_FLAG_PREFER) { | |
1361 | p->prio = | |
1362 | (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT; | |
1363 | } else { | |
1364 | p->prio = --least_priority; | |
1365 | } | |
5d337b91 | 1366 | spin_unlock(&swap_lock); |
1da177e4 LT |
1367 | name = getname(specialfile); |
1368 | error = PTR_ERR(name); | |
1369 | if (IS_ERR(name)) { | |
1370 | name = NULL; | |
1371 | goto bad_swap_2; | |
1372 | } | |
1373 | swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0); | |
1374 | error = PTR_ERR(swap_file); | |
1375 | if (IS_ERR(swap_file)) { | |
1376 | swap_file = NULL; | |
1377 | goto bad_swap_2; | |
1378 | } | |
1379 | ||
1380 | p->swap_file = swap_file; | |
1381 | mapping = swap_file->f_mapping; | |
1382 | inode = mapping->host; | |
1383 | ||
1384 | error = -EBUSY; | |
1385 | for (i = 0; i < nr_swapfiles; i++) { | |
1386 | struct swap_info_struct *q = &swap_info[i]; | |
1387 | ||
1388 | if (i == type || !q->swap_file) | |
1389 | continue; | |
1390 | if (mapping == q->swap_file->f_mapping) | |
1391 | goto bad_swap; | |
1392 | } | |
1393 | ||
1394 | error = -EINVAL; | |
1395 | if (S_ISBLK(inode->i_mode)) { | |
1396 | bdev = I_BDEV(inode); | |
1397 | error = bd_claim(bdev, sys_swapon); | |
1398 | if (error < 0) { | |
1399 | bdev = NULL; | |
f7b3a435 | 1400 | error = -EINVAL; |
1da177e4 LT |
1401 | goto bad_swap; |
1402 | } | |
1403 | p->old_block_size = block_size(bdev); | |
1404 | error = set_blocksize(bdev, PAGE_SIZE); | |
1405 | if (error < 0) | |
1406 | goto bad_swap; | |
1407 | p->bdev = bdev; | |
1408 | } else if (S_ISREG(inode->i_mode)) { | |
1409 | p->bdev = inode->i_sb->s_bdev; | |
1b1dcc1b | 1410 | mutex_lock(&inode->i_mutex); |
1da177e4 LT |
1411 | did_down = 1; |
1412 | if (IS_SWAPFILE(inode)) { | |
1413 | error = -EBUSY; | |
1414 | goto bad_swap; | |
1415 | } | |
1416 | } else { | |
1417 | goto bad_swap; | |
1418 | } | |
1419 | ||
1420 | swapfilesize = i_size_read(inode) >> PAGE_SHIFT; | |
1421 | ||
1422 | /* | |
1423 | * Read the swap header. | |
1424 | */ | |
1425 | if (!mapping->a_ops->readpage) { | |
1426 | error = -EINVAL; | |
1427 | goto bad_swap; | |
1428 | } | |
1429 | page = read_cache_page(mapping, 0, | |
1430 | (filler_t *)mapping->a_ops->readpage, swap_file); | |
1431 | if (IS_ERR(page)) { | |
1432 | error = PTR_ERR(page); | |
1433 | goto bad_swap; | |
1434 | } | |
1435 | wait_on_page_locked(page); | |
1436 | if (!PageUptodate(page)) | |
1437 | goto bad_swap; | |
1438 | kmap(page); | |
1439 | swap_header = page_address(page); | |
1440 | ||
1441 | if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10)) | |
1442 | swap_header_version = 1; | |
1443 | else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10)) | |
1444 | swap_header_version = 2; | |
1445 | else { | |
e97a3111 | 1446 | printk(KERN_ERR "Unable to find swap-space signature\n"); |
1da177e4 LT |
1447 | error = -EINVAL; |
1448 | goto bad_swap; | |
1449 | } | |
1450 | ||
1451 | switch (swap_header_version) { | |
1452 | case 1: | |
1453 | printk(KERN_ERR "version 0 swap is no longer supported. " | |
1454 | "Use mkswap -v1 %s\n", name); | |
1455 | error = -EINVAL; | |
1456 | goto bad_swap; | |
1457 | case 2: | |
1458 | /* Check the swap header's sub-version and the size of | |
1459 | the swap file and bad block lists */ | |
1460 | if (swap_header->info.version != 1) { | |
1461 | printk(KERN_WARNING | |
1462 | "Unable to handle swap header version %d\n", | |
1463 | swap_header->info.version); | |
1464 | error = -EINVAL; | |
1465 | goto bad_swap; | |
1466 | } | |
1467 | ||
1468 | p->lowest_bit = 1; | |
52b7efdb HD |
1469 | p->cluster_next = 1; |
1470 | ||
1da177e4 LT |
1471 | /* |
1472 | * Find out how many pages are allowed for a single swap | |
1473 | * device. There are two limiting factors: 1) the number of | |
1474 | * bits for the swap offset in the swp_entry_t type and | |
1475 | * 2) the number of bits in the a swap pte as defined by | |
1476 | * the different architectures. In order to find the | |
1477 | * largest possible bit mask a swap entry with swap type 0 | |
1478 | * and swap offset ~0UL is created, encoded to a swap pte, | |
1479 | * decoded to a swp_entry_t again and finally the swap | |
1480 | * offset is extracted. This will mask all the bits from | |
1481 | * the initial ~0UL mask that can't be encoded in either | |
1482 | * the swp_entry_t or the architecture definition of a | |
1483 | * swap pte. | |
1484 | */ | |
1485 | maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1; | |
1486 | if (maxpages > swap_header->info.last_page) | |
1487 | maxpages = swap_header->info.last_page; | |
1488 | p->highest_bit = maxpages - 1; | |
1489 | ||
1490 | error = -EINVAL; | |
e2244ec2 HD |
1491 | if (!maxpages) |
1492 | goto bad_swap; | |
1493 | if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) | |
1494 | goto bad_swap; | |
1da177e4 LT |
1495 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
1496 | goto bad_swap; | |
cd105df4 | 1497 | |
1da177e4 LT |
1498 | /* OK, set up the swap map and apply the bad block list */ |
1499 | if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) { | |
1500 | error = -ENOMEM; | |
1501 | goto bad_swap; | |
1502 | } | |
1503 | ||
1504 | error = 0; | |
1505 | memset(p->swap_map, 0, maxpages * sizeof(short)); | |
cd105df4 TK |
1506 | for (i = 0; i < swap_header->info.nr_badpages; i++) { |
1507 | int page_nr = swap_header->info.badpages[i]; | |
1508 | if (page_nr <= 0 || page_nr >= swap_header->info.last_page) | |
1da177e4 LT |
1509 | error = -EINVAL; |
1510 | else | |
cd105df4 | 1511 | p->swap_map[page_nr] = SWAP_MAP_BAD; |
1da177e4 LT |
1512 | } |
1513 | nr_good_pages = swap_header->info.last_page - | |
1514 | swap_header->info.nr_badpages - | |
1515 | 1 /* header page */; | |
cd105df4 | 1516 | if (error) |
1da177e4 LT |
1517 | goto bad_swap; |
1518 | } | |
e2244ec2 | 1519 | |
1da177e4 LT |
1520 | if (swapfilesize && maxpages > swapfilesize) { |
1521 | printk(KERN_WARNING | |
1522 | "Swap area shorter than signature indicates\n"); | |
1523 | error = -EINVAL; | |
1524 | goto bad_swap; | |
1525 | } | |
e2244ec2 HD |
1526 | if (nr_good_pages) { |
1527 | p->swap_map[0] = SWAP_MAP_BAD; | |
1528 | p->max = maxpages; | |
1529 | p->pages = nr_good_pages; | |
53092a74 HD |
1530 | nr_extents = setup_swap_extents(p, &span); |
1531 | if (nr_extents < 0) { | |
1532 | error = nr_extents; | |
e2244ec2 | 1533 | goto bad_swap; |
53092a74 | 1534 | } |
e2244ec2 HD |
1535 | nr_good_pages = p->pages; |
1536 | } | |
1da177e4 LT |
1537 | if (!nr_good_pages) { |
1538 | printk(KERN_WARNING "Empty swap-file\n"); | |
1539 | error = -EINVAL; | |
1540 | goto bad_swap; | |
1541 | } | |
1da177e4 LT |
1542 | |
1543 | down(&swapon_sem); | |
5d337b91 | 1544 | spin_lock(&swap_lock); |
1da177e4 LT |
1545 | p->flags = SWP_ACTIVE; |
1546 | nr_swap_pages += nr_good_pages; | |
1547 | total_swap_pages += nr_good_pages; | |
53092a74 | 1548 | |
6eb396dc | 1549 | printk(KERN_INFO "Adding %uk swap on %s. " |
53092a74 HD |
1550 | "Priority:%d extents:%d across:%lluk\n", |
1551 | nr_good_pages<<(PAGE_SHIFT-10), name, p->prio, | |
1552 | nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10)); | |
1da177e4 LT |
1553 | |
1554 | /* insert swap space into swap_list: */ | |
1555 | prev = -1; | |
1556 | for (i = swap_list.head; i >= 0; i = swap_info[i].next) { | |
1557 | if (p->prio >= swap_info[i].prio) { | |
1558 | break; | |
1559 | } | |
1560 | prev = i; | |
1561 | } | |
1562 | p->next = i; | |
1563 | if (prev < 0) { | |
1564 | swap_list.head = swap_list.next = p - swap_info; | |
1565 | } else { | |
1566 | swap_info[prev].next = p - swap_info; | |
1567 | } | |
5d337b91 | 1568 | spin_unlock(&swap_lock); |
1da177e4 LT |
1569 | up(&swapon_sem); |
1570 | error = 0; | |
1571 | goto out; | |
1572 | bad_swap: | |
1573 | if (bdev) { | |
1574 | set_blocksize(bdev, p->old_block_size); | |
1575 | bd_release(bdev); | |
1576 | } | |
4cd3bb10 | 1577 | destroy_swap_extents(p); |
1da177e4 | 1578 | bad_swap_2: |
5d337b91 | 1579 | spin_lock(&swap_lock); |
1da177e4 LT |
1580 | swap_map = p->swap_map; |
1581 | p->swap_file = NULL; | |
1582 | p->swap_map = NULL; | |
1583 | p->flags = 0; | |
1584 | if (!(swap_flags & SWAP_FLAG_PREFER)) | |
1585 | ++least_priority; | |
5d337b91 | 1586 | spin_unlock(&swap_lock); |
1da177e4 LT |
1587 | vfree(swap_map); |
1588 | if (swap_file) | |
1589 | filp_close(swap_file, NULL); | |
1590 | out: | |
1591 | if (page && !IS_ERR(page)) { | |
1592 | kunmap(page); | |
1593 | page_cache_release(page); | |
1594 | } | |
1595 | if (name) | |
1596 | putname(name); | |
1597 | if (did_down) { | |
1598 | if (!error) | |
1599 | inode->i_flags |= S_SWAPFILE; | |
1b1dcc1b | 1600 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
1601 | } |
1602 | return error; | |
1603 | } | |
1604 | ||
1605 | void si_swapinfo(struct sysinfo *val) | |
1606 | { | |
1607 | unsigned int i; | |
1608 | unsigned long nr_to_be_unused = 0; | |
1609 | ||
5d337b91 | 1610 | spin_lock(&swap_lock); |
1da177e4 LT |
1611 | for (i = 0; i < nr_swapfiles; i++) { |
1612 | if (!(swap_info[i].flags & SWP_USED) || | |
1613 | (swap_info[i].flags & SWP_WRITEOK)) | |
1614 | continue; | |
1615 | nr_to_be_unused += swap_info[i].inuse_pages; | |
1616 | } | |
1617 | val->freeswap = nr_swap_pages + nr_to_be_unused; | |
1618 | val->totalswap = total_swap_pages + nr_to_be_unused; | |
5d337b91 | 1619 | spin_unlock(&swap_lock); |
1da177e4 LT |
1620 | } |
1621 | ||
1622 | /* | |
1623 | * Verify that a swap entry is valid and increment its swap map count. | |
1624 | * | |
1625 | * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as | |
1626 | * "permanent", but will be reclaimed by the next swapoff. | |
1627 | */ | |
1628 | int swap_duplicate(swp_entry_t entry) | |
1629 | { | |
1630 | struct swap_info_struct * p; | |
1631 | unsigned long offset, type; | |
1632 | int result = 0; | |
1633 | ||
1634 | type = swp_type(entry); | |
1635 | if (type >= nr_swapfiles) | |
1636 | goto bad_file; | |
1637 | p = type + swap_info; | |
1638 | offset = swp_offset(entry); | |
1639 | ||
5d337b91 | 1640 | spin_lock(&swap_lock); |
1da177e4 LT |
1641 | if (offset < p->max && p->swap_map[offset]) { |
1642 | if (p->swap_map[offset] < SWAP_MAP_MAX - 1) { | |
1643 | p->swap_map[offset]++; | |
1644 | result = 1; | |
1645 | } else if (p->swap_map[offset] <= SWAP_MAP_MAX) { | |
1646 | if (swap_overflow++ < 5) | |
1647 | printk(KERN_WARNING "swap_dup: swap entry overflow\n"); | |
1648 | p->swap_map[offset] = SWAP_MAP_MAX; | |
1649 | result = 1; | |
1650 | } | |
1651 | } | |
5d337b91 | 1652 | spin_unlock(&swap_lock); |
1da177e4 LT |
1653 | out: |
1654 | return result; | |
1655 | ||
1656 | bad_file: | |
1657 | printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val); | |
1658 | goto out; | |
1659 | } | |
1660 | ||
1661 | struct swap_info_struct * | |
1662 | get_swap_info_struct(unsigned type) | |
1663 | { | |
1664 | return &swap_info[type]; | |
1665 | } | |
1666 | ||
1667 | /* | |
5d337b91 | 1668 | * swap_lock prevents swap_map being freed. Don't grab an extra |
1da177e4 LT |
1669 | * reference on the swaphandle, it doesn't matter if it becomes unused. |
1670 | */ | |
1671 | int valid_swaphandles(swp_entry_t entry, unsigned long *offset) | |
1672 | { | |
1673 | int ret = 0, i = 1 << page_cluster; | |
1674 | unsigned long toff; | |
1675 | struct swap_info_struct *swapdev = swp_type(entry) + swap_info; | |
1676 | ||
1677 | if (!page_cluster) /* no readahead */ | |
1678 | return 0; | |
1679 | toff = (swp_offset(entry) >> page_cluster) << page_cluster; | |
1680 | if (!toff) /* first page is swap header */ | |
1681 | toff++, i--; | |
1682 | *offset = toff; | |
1683 | ||
5d337b91 | 1684 | spin_lock(&swap_lock); |
1da177e4 LT |
1685 | do { |
1686 | /* Don't read-ahead past the end of the swap area */ | |
1687 | if (toff >= swapdev->max) | |
1688 | break; | |
1689 | /* Don't read in free or bad pages */ | |
1690 | if (!swapdev->swap_map[toff]) | |
1691 | break; | |
1692 | if (swapdev->swap_map[toff] == SWAP_MAP_BAD) | |
1693 | break; | |
1694 | toff++; | |
1695 | ret++; | |
1696 | } while (--i); | |
5d337b91 | 1697 | spin_unlock(&swap_lock); |
1da177e4 LT |
1698 | return ret; |
1699 | } |