blob: 1f9cf0d073b84caad71234ddfb091618906d3047 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Ingo Molnarfc0abb12006-01-18 17:42:33 -080028#include <linux/mutex.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080029#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#include <linux/syscalls.h>
31
32#include <asm/pgtable.h>
33#include <asm/tlbflush.h>
34#include <linux/swapops.h>
35
Hugh Dickins5d337b92005-09-03 15:54:41 -070036DEFINE_SPINLOCK(swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070037unsigned int nr_swapfiles;
38long total_swap_pages;
39static int swap_overflow;
40
Linus Torvalds1da177e2005-04-16 15:20:36 -070041static const char Bad_file[] = "Bad swap file entry ";
42static const char Unused_file[] = "Unused swap file entry ";
43static const char Bad_offset[] = "Bad swap offset entry ";
44static const char Unused_offset[] = "Unused swap offset entry ";
45
46struct swap_list_t swap_list = {-1, -1};
47
48struct swap_info_struct swap_info[MAX_SWAPFILES];
49
Ingo Molnarfc0abb12006-01-18 17:42:33 -080050static DEFINE_MUTEX(swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
52/*
53 * We need this because the bdev->unplug_fn can sleep and we cannot
Hugh Dickins5d337b92005-09-03 15:54:41 -070054 * hold swap_lock while calling the unplug_fn. And swap_lock
Ingo Molnarfc0abb12006-01-18 17:42:33 -080055 * cannot be turned into a mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 */
57static DECLARE_RWSEM(swap_unplug_sem);
58
Linus Torvalds1da177e2005-04-16 15:20:36 -070059void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page)
60{
61 swp_entry_t entry;
62
63 down_read(&swap_unplug_sem);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070064 entry.val = page_private(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 if (PageSwapCache(page)) {
66 struct block_device *bdev = swap_info[swp_type(entry)].bdev;
67 struct backing_dev_info *bdi;
68
69 /*
70 * If the page is removed from swapcache from under us (with a
71 * racy try_to_unuse/swapoff) we need an additional reference
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070072 * count to avoid reading garbage from page_private(page) above.
73 * If the WARN_ON triggers during a swapoff it maybe the race
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 * condition and it's harmless. However if it triggers without
75 * swapoff it signals a problem.
76 */
77 WARN_ON(page_count(page) <= 1);
78
79 bdi = bdev->bd_inode->i_mapping->backing_dev_info;
McMullan, Jasonba323112005-05-16 21:53:40 -070080 blk_run_backing_dev(bdi, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 }
82 up_read(&swap_unplug_sem);
83}
84
Hugh Dickins048c27f2005-09-03 15:54:40 -070085#define SWAPFILE_CLUSTER 256
86#define LATENCY_LIMIT 256
87
Hugh Dickins6eb396d2005-09-03 15:54:35 -070088static inline unsigned long scan_swap_map(struct swap_info_struct *si)
Linus Torvalds1da177e2005-04-16 15:20:36 -070089{
Hugh Dickins7dfad412005-09-03 15:54:38 -070090 unsigned long offset, last_in_cluster;
Hugh Dickins048c27f2005-09-03 15:54:40 -070091 int latency_ration = LATENCY_LIMIT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070092
Hugh Dickins7dfad412005-09-03 15:54:38 -070093 /*
94 * We try to cluster swap pages by allocating them sequentially
95 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this
96 * way, however, we resort to first-free allocation, starting
97 * a new cluster. This prevents us from scattering swap pages
98 * all over the entire swap partition, so that we reduce
99 * overall disk seek times between swap pages. -- sct
100 * But we do now try to find an empty cluster. -Andrea
101 */
102
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700103 si->flags += SWP_SCANNING;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700104 if (unlikely(!si->cluster_nr)) {
105 si->cluster_nr = SWAPFILE_CLUSTER - 1;
106 if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER)
107 goto lowest;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700108 spin_unlock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700109
110 offset = si->lowest_bit;
111 last_in_cluster = offset + SWAPFILE_CLUSTER - 1;
112
113 /* Locate the first empty (unaligned) cluster */
114 for (; last_in_cluster <= si->highest_bit; offset++) {
115 if (si->swap_map[offset])
116 last_in_cluster = offset + SWAPFILE_CLUSTER;
117 else if (offset == last_in_cluster) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700118 spin_lock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700119 si->cluster_next = offset-SWAPFILE_CLUSTER-1;
120 goto cluster;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 }
Hugh Dickins048c27f2005-09-03 15:54:40 -0700122 if (unlikely(--latency_ration < 0)) {
123 cond_resched();
124 latency_ration = LATENCY_LIMIT;
125 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700126 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700127 spin_lock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700128 goto lowest;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700130
131 si->cluster_nr--;
132cluster:
133 offset = si->cluster_next;
134 if (offset > si->highest_bit)
135lowest: offset = si->lowest_bit;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700136checks: if (!(si->flags & SWP_WRITEOK))
137 goto no_page;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700138 if (!si->highest_bit)
139 goto no_page;
140 if (!si->swap_map[offset]) {
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700141 if (offset == si->lowest_bit)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 si->lowest_bit++;
143 if (offset == si->highest_bit)
144 si->highest_bit--;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700145 si->inuse_pages++;
146 if (si->inuse_pages == si->pages) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 si->lowest_bit = si->max;
148 si->highest_bit = 0;
149 }
150 si->swap_map[offset] = 1;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700151 si->cluster_next = offset + 1;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700152 si->flags -= SWP_SCANNING;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 return offset;
154 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700155
Hugh Dickins5d337b92005-09-03 15:54:41 -0700156 spin_unlock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700157 while (++offset <= si->highest_bit) {
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700158 if (!si->swap_map[offset]) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700159 spin_lock(&swap_lock);
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700160 goto checks;
161 }
Hugh Dickins048c27f2005-09-03 15:54:40 -0700162 if (unlikely(--latency_ration < 0)) {
163 cond_resched();
164 latency_ration = LATENCY_LIMIT;
165 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700166 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700167 spin_lock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700168 goto lowest;
169
170no_page:
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700171 si->flags -= SWP_SCANNING;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 return 0;
173}
174
175swp_entry_t get_swap_page(void)
176{
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700177 struct swap_info_struct *si;
178 pgoff_t offset;
179 int type, next;
180 int wrapped = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181
Hugh Dickins5d337b92005-09-03 15:54:41 -0700182 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 if (nr_swap_pages <= 0)
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700184 goto noswap;
185 nr_swap_pages--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700187 for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) {
188 si = swap_info + type;
189 next = si->next;
190 if (next < 0 ||
191 (!wrapped && si->prio != swap_info[next].prio)) {
192 next = swap_list.head;
193 wrapped++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 }
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700195
196 if (!si->highest_bit)
197 continue;
198 if (!(si->flags & SWP_WRITEOK))
199 continue;
200
201 swap_list.next = next;
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700202 offset = scan_swap_map(si);
Hugh Dickins5d337b92005-09-03 15:54:41 -0700203 if (offset) {
204 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700205 return swp_entry(type, offset);
Hugh Dickins5d337b92005-09-03 15:54:41 -0700206 }
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700207 next = swap_list.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208 }
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700209
210 nr_swap_pages++;
211noswap:
Hugh Dickins5d337b92005-09-03 15:54:41 -0700212 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700213 return (swp_entry_t) {0};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214}
215
Rafael J. Wysocki3a291a22006-01-06 00:16:37 -0800216swp_entry_t get_swap_page_of_type(int type)
217{
218 struct swap_info_struct *si;
219 pgoff_t offset;
220
221 spin_lock(&swap_lock);
222 si = swap_info + type;
223 if (si->flags & SWP_WRITEOK) {
224 nr_swap_pages--;
225 offset = scan_swap_map(si);
226 if (offset) {
227 spin_unlock(&swap_lock);
228 return swp_entry(type, offset);
229 }
230 nr_swap_pages++;
231 }
232 spin_unlock(&swap_lock);
233 return (swp_entry_t) {0};
234}
235
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236static struct swap_info_struct * swap_info_get(swp_entry_t entry)
237{
238 struct swap_info_struct * p;
239 unsigned long offset, type;
240
241 if (!entry.val)
242 goto out;
243 type = swp_type(entry);
244 if (type >= nr_swapfiles)
245 goto bad_nofile;
246 p = & swap_info[type];
247 if (!(p->flags & SWP_USED))
248 goto bad_device;
249 offset = swp_offset(entry);
250 if (offset >= p->max)
251 goto bad_offset;
252 if (!p->swap_map[offset])
253 goto bad_free;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700254 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 return p;
256
257bad_free:
258 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val);
259 goto out;
260bad_offset:
261 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val);
262 goto out;
263bad_device:
264 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val);
265 goto out;
266bad_nofile:
267 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val);
268out:
269 return NULL;
270}
271
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272static int swap_entry_free(struct swap_info_struct *p, unsigned long offset)
273{
274 int count = p->swap_map[offset];
275
276 if (count < SWAP_MAP_MAX) {
277 count--;
278 p->swap_map[offset] = count;
279 if (!count) {
280 if (offset < p->lowest_bit)
281 p->lowest_bit = offset;
282 if (offset > p->highest_bit)
283 p->highest_bit = offset;
Hugh Dickins89d09a22005-09-03 15:54:36 -0700284 if (p->prio > swap_info[swap_list.next].prio)
285 swap_list.next = p - swap_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 nr_swap_pages++;
287 p->inuse_pages--;
288 }
289 }
290 return count;
291}
292
293/*
294 * Caller has made sure that the swapdevice corresponding to entry
295 * is still around or has not been recycled.
296 */
297void swap_free(swp_entry_t entry)
298{
299 struct swap_info_struct * p;
300
301 p = swap_info_get(entry);
302 if (p) {
303 swap_entry_free(p, swp_offset(entry));
Hugh Dickins5d337b92005-09-03 15:54:41 -0700304 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 }
306}
307
308/*
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700309 * How many references to page are currently swapped out?
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 */
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700311static inline int page_swapcount(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312{
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700313 int count = 0;
314 struct swap_info_struct *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 swp_entry_t entry;
316
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700317 entry.val = page_private(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 p = swap_info_get(entry);
319 if (p) {
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700320 /* Subtract the 1 for the swap cache itself */
321 count = p->swap_map[swp_offset(entry)] - 1;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700322 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 }
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700324 return count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325}
326
327/*
328 * We can use this swap cache entry directly
329 * if there are no other references to it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 */
331int can_share_swap_page(struct page *page)
332{
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700333 int count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700335 BUG_ON(!PageLocked(page));
336 count = page_mapcount(page);
337 if (count <= 1 && PageSwapCache(page))
338 count += page_swapcount(page);
339 return count == 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340}
341
342/*
343 * Work out if there are any other processes sharing this
344 * swap cache page. Free it if you can. Return success.
345 */
346int remove_exclusive_swap_page(struct page *page)
347{
348 int retval;
349 struct swap_info_struct * p;
350 swp_entry_t entry;
351
352 BUG_ON(PagePrivate(page));
353 BUG_ON(!PageLocked(page));
354
355 if (!PageSwapCache(page))
356 return 0;
357 if (PageWriteback(page))
358 return 0;
359 if (page_count(page) != 2) /* 2: us + cache */
360 return 0;
361
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700362 entry.val = page_private(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 p = swap_info_get(entry);
364 if (!p)
365 return 0;
366
367 /* Is the only swap cache user the cache itself? */
368 retval = 0;
369 if (p->swap_map[swp_offset(entry)] == 1) {
370 /* Recheck the page count with the swapcache lock held.. */
371 write_lock_irq(&swapper_space.tree_lock);
372 if ((page_count(page) == 2) && !PageWriteback(page)) {
373 __delete_from_swap_cache(page);
374 SetPageDirty(page);
375 retval = 1;
376 }
377 write_unlock_irq(&swapper_space.tree_lock);
378 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700379 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380
381 if (retval) {
382 swap_free(entry);
383 page_cache_release(page);
384 }
385
386 return retval;
387}
388
389/*
390 * Free the swap entry like above, but also try to
391 * free the page cache entry if it is the last user.
392 */
393void free_swap_and_cache(swp_entry_t entry)
394{
395 struct swap_info_struct * p;
396 struct page *page = NULL;
397
398 p = swap_info_get(entry);
399 if (p) {
400 if (swap_entry_free(p, swp_offset(entry)) == 1)
401 page = find_trylock_page(&swapper_space, entry.val);
Hugh Dickins5d337b92005-09-03 15:54:41 -0700402 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 }
404 if (page) {
405 int one_user;
406
407 BUG_ON(PagePrivate(page));
408 page_cache_get(page);
409 one_user = (page_count(page) == 2);
410 /* Only cache user (+us), or swap space full? Free it! */
411 if (!PageWriteback(page) && (one_user || vm_swap_full())) {
412 delete_from_swap_cache(page);
413 SetPageDirty(page);
414 }
415 unlock_page(page);
416 page_cache_release(page);
417 }
418}
419
420/*
Hugh Dickins72866f62005-10-29 18:15:55 -0700421 * No need to decide whether this PTE shares the swap entry with others,
422 * just let do_wp_page work it out if a write is requested later - to
423 * force COW, vm_page_prot omits write permission from any private vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 */
425static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
426 unsigned long addr, swp_entry_t entry, struct page *page)
427{
Hugh Dickins42946212005-10-29 18:16:05 -0700428 inc_mm_counter(vma->vm_mm, anon_rss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 get_page(page);
430 set_pte_at(vma->vm_mm, addr, pte,
431 pte_mkold(mk_pte(page, vma->vm_page_prot)));
432 page_add_anon_rmap(page, vma, addr);
433 swap_free(entry);
434 /*
435 * Move the page to the active list so it is not
436 * immediately swapped out again after swapon.
437 */
438 activate_page(page);
439}
440
441static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
442 unsigned long addr, unsigned long end,
443 swp_entry_t entry, struct page *page)
444{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 pte_t swp_pte = swp_entry_to_pte(entry);
Hugh Dickins705e87c2005-10-29 18:16:27 -0700446 pte_t *pte;
447 spinlock_t *ptl;
448 int found = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449
Hugh Dickins705e87c2005-10-29 18:16:27 -0700450 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 do {
452 /*
453 * swapoff spends a _lot_ of time in this loop!
454 * Test inline before going to call unuse_pte.
455 */
456 if (unlikely(pte_same(*pte, swp_pte))) {
Hugh Dickins705e87c2005-10-29 18:16:27 -0700457 unuse_pte(vma, pte++, addr, entry, page);
458 found = 1;
459 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 }
461 } while (pte++, addr += PAGE_SIZE, addr != end);
Hugh Dickins705e87c2005-10-29 18:16:27 -0700462 pte_unmap_unlock(pte - 1, ptl);
463 return found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464}
465
466static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
467 unsigned long addr, unsigned long end,
468 swp_entry_t entry, struct page *page)
469{
470 pmd_t *pmd;
471 unsigned long next;
472
473 pmd = pmd_offset(pud, addr);
474 do {
475 next = pmd_addr_end(addr, end);
476 if (pmd_none_or_clear_bad(pmd))
477 continue;
478 if (unuse_pte_range(vma, pmd, addr, next, entry, page))
479 return 1;
480 } while (pmd++, addr = next, addr != end);
481 return 0;
482}
483
484static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
485 unsigned long addr, unsigned long end,
486 swp_entry_t entry, struct page *page)
487{
488 pud_t *pud;
489 unsigned long next;
490
491 pud = pud_offset(pgd, addr);
492 do {
493 next = pud_addr_end(addr, end);
494 if (pud_none_or_clear_bad(pud))
495 continue;
496 if (unuse_pmd_range(vma, pud, addr, next, entry, page))
497 return 1;
498 } while (pud++, addr = next, addr != end);
499 return 0;
500}
501
502static int unuse_vma(struct vm_area_struct *vma,
503 swp_entry_t entry, struct page *page)
504{
505 pgd_t *pgd;
506 unsigned long addr, end, next;
507
508 if (page->mapping) {
509 addr = page_address_in_vma(page, vma);
510 if (addr == -EFAULT)
511 return 0;
512 else
513 end = addr + PAGE_SIZE;
514 } else {
515 addr = vma->vm_start;
516 end = vma->vm_end;
517 }
518
519 pgd = pgd_offset(vma->vm_mm, addr);
520 do {
521 next = pgd_addr_end(addr, end);
522 if (pgd_none_or_clear_bad(pgd))
523 continue;
524 if (unuse_pud_range(vma, pgd, addr, next, entry, page))
525 return 1;
526 } while (pgd++, addr = next, addr != end);
527 return 0;
528}
529
530static int unuse_mm(struct mm_struct *mm,
531 swp_entry_t entry, struct page *page)
532{
533 struct vm_area_struct *vma;
534
535 if (!down_read_trylock(&mm->mmap_sem)) {
536 /*
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700537 * Activate page so shrink_cache is unlikely to unmap its
538 * ptes while lock is dropped, so swapoff can make progress.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 */
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700540 activate_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 unlock_page(page);
542 down_read(&mm->mmap_sem);
543 lock_page(page);
544 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545 for (vma = mm->mmap; vma; vma = vma->vm_next) {
546 if (vma->anon_vma && unuse_vma(vma, entry, page))
547 break;
548 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 up_read(&mm->mmap_sem);
550 /*
551 * Currently unuse_mm cannot fail, but leave error handling
552 * at call sites for now, since we change it from time to time.
553 */
554 return 0;
555}
556
Christoph Lametera3351e52006-02-01 03:05:39 -0800557#ifdef CONFIG_MIGRATION
558int remove_vma_swap(struct vm_area_struct *vma, struct page *page)
559{
560 swp_entry_t entry = { .val = page_private(page) };
561
562 return unuse_vma(vma, entry, page);
563}
564#endif
565
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566/*
567 * Scan swap_map from current position to next entry still in use.
568 * Recycle to start on reaching the end, returning 0 when empty.
569 */
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700570static unsigned int find_next_to_unuse(struct swap_info_struct *si,
571 unsigned int prev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572{
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700573 unsigned int max = si->max;
574 unsigned int i = prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 int count;
576
577 /*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700578 * No need for swap_lock here: we're just looking
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 * for whether an entry is in use, not modifying it; false
580 * hits are okay, and sys_swapoff() has already prevented new
Hugh Dickins5d337b92005-09-03 15:54:41 -0700581 * allocations from this area (while holding swap_lock).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 */
583 for (;;) {
584 if (++i >= max) {
585 if (!prev) {
586 i = 0;
587 break;
588 }
589 /*
590 * No entries in use at top of swap_map,
591 * loop back to start and recheck there.
592 */
593 max = prev + 1;
594 prev = 0;
595 i = 1;
596 }
597 count = si->swap_map[i];
598 if (count && count != SWAP_MAP_BAD)
599 break;
600 }
601 return i;
602}
603
604/*
605 * We completely avoid races by reading each swap page in advance,
606 * and then search for the process using it. All the necessary
607 * page table adjustments can then be made atomically.
608 */
609static int try_to_unuse(unsigned int type)
610{
611 struct swap_info_struct * si = &swap_info[type];
612 struct mm_struct *start_mm;
613 unsigned short *swap_map;
614 unsigned short swcount;
615 struct page *page;
616 swp_entry_t entry;
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700617 unsigned int i = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618 int retval = 0;
619 int reset_overflow = 0;
620 int shmem;
621
622 /*
623 * When searching mms for an entry, a good strategy is to
624 * start at the first mm we freed the previous entry from
625 * (though actually we don't notice whether we or coincidence
626 * freed the entry). Initialize this start_mm with a hold.
627 *
628 * A simpler strategy would be to start at the last mm we
629 * freed the previous entry from; but that would take less
630 * advantage of mmlist ordering, which clusters forked mms
631 * together, child after parent. If we race with dup_mmap(), we
632 * prefer to resolve parent before child, lest we miss entries
633 * duplicated after we scanned child: using last mm would invert
634 * that. Though it's only a serious concern when an overflowed
635 * swap count is reset from SWAP_MAP_MAX, preventing a rescan.
636 */
637 start_mm = &init_mm;
638 atomic_inc(&init_mm.mm_users);
639
640 /*
641 * Keep on scanning until all entries have gone. Usually,
642 * one pass through swap_map is enough, but not necessarily:
643 * there are races when an instance of an entry might be missed.
644 */
645 while ((i = find_next_to_unuse(si, i)) != 0) {
646 if (signal_pending(current)) {
647 retval = -EINTR;
648 break;
649 }
650
651 /*
652 * Get a page for the entry, using the existing swap
653 * cache page if there is one. Otherwise, get a clean
654 * page and read the swap into it.
655 */
656 swap_map = &si->swap_map[i];
657 entry = swp_entry(type, i);
Christoph Lameterb16664e2006-02-01 03:05:36 -0800658again:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 page = read_swap_cache_async(entry, NULL, 0);
660 if (!page) {
661 /*
662 * Either swap_duplicate() failed because entry
663 * has been freed independently, and will not be
664 * reused since sys_swapoff() already disabled
665 * allocation from here, or alloc_page() failed.
666 */
667 if (!*swap_map)
668 continue;
669 retval = -ENOMEM;
670 break;
671 }
672
673 /*
674 * Don't hold on to start_mm if it looks like exiting.
675 */
676 if (atomic_read(&start_mm->mm_users) == 1) {
677 mmput(start_mm);
678 start_mm = &init_mm;
679 atomic_inc(&init_mm.mm_users);
680 }
681
682 /*
683 * Wait for and lock page. When do_swap_page races with
684 * try_to_unuse, do_swap_page can handle the fault much
685 * faster than try_to_unuse can locate the entry. This
686 * apparently redundant "wait_on_page_locked" lets try_to_unuse
687 * defer to do_swap_page in such a case - in some tests,
688 * do_swap_page and try_to_unuse repeatedly compete.
689 */
690 wait_on_page_locked(page);
691 wait_on_page_writeback(page);
692 lock_page(page);
Christoph Lameterb16664e2006-02-01 03:05:36 -0800693 if (!PageSwapCache(page)) {
694 /* Page migration has occured */
695 unlock_page(page);
696 page_cache_release(page);
697 goto again;
698 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 wait_on_page_writeback(page);
700
701 /*
702 * Remove all references to entry.
703 * Whenever we reach init_mm, there's no address space
704 * to search, but use it as a reminder to search shmem.
705 */
706 shmem = 0;
707 swcount = *swap_map;
708 if (swcount > 1) {
709 if (start_mm == &init_mm)
710 shmem = shmem_unuse(entry, page);
711 else
712 retval = unuse_mm(start_mm, entry, page);
713 }
714 if (*swap_map > 1) {
715 int set_start_mm = (*swap_map >= swcount);
716 struct list_head *p = &start_mm->mmlist;
717 struct mm_struct *new_start_mm = start_mm;
718 struct mm_struct *prev_mm = start_mm;
719 struct mm_struct *mm;
720
721 atomic_inc(&new_start_mm->mm_users);
722 atomic_inc(&prev_mm->mm_users);
723 spin_lock(&mmlist_lock);
724 while (*swap_map > 1 && !retval &&
725 (p = p->next) != &start_mm->mmlist) {
726 mm = list_entry(p, struct mm_struct, mmlist);
727 if (atomic_inc_return(&mm->mm_users) == 1) {
728 atomic_dec(&mm->mm_users);
729 continue;
730 }
731 spin_unlock(&mmlist_lock);
732 mmput(prev_mm);
733 prev_mm = mm;
734
735 cond_resched();
736
737 swcount = *swap_map;
738 if (swcount <= 1)
739 ;
740 else if (mm == &init_mm) {
741 set_start_mm = 1;
742 shmem = shmem_unuse(entry, page);
743 } else
744 retval = unuse_mm(mm, entry, page);
745 if (set_start_mm && *swap_map < swcount) {
746 mmput(new_start_mm);
747 atomic_inc(&mm->mm_users);
748 new_start_mm = mm;
749 set_start_mm = 0;
750 }
751 spin_lock(&mmlist_lock);
752 }
753 spin_unlock(&mmlist_lock);
754 mmput(prev_mm);
755 mmput(start_mm);
756 start_mm = new_start_mm;
757 }
758 if (retval) {
759 unlock_page(page);
760 page_cache_release(page);
761 break;
762 }
763
764 /*
765 * How could swap count reach 0x7fff when the maximum
766 * pid is 0x7fff, and there's no way to repeat a swap
767 * page within an mm (except in shmem, where it's the
768 * shared object which takes the reference count)?
769 * We believe SWAP_MAP_MAX cannot occur in Linux 2.4.
770 *
771 * If that's wrong, then we should worry more about
772 * exit_mmap() and do_munmap() cases described above:
773 * we might be resetting SWAP_MAP_MAX too early here.
774 * We know "Undead"s can happen, they're okay, so don't
775 * report them; but do report if we reset SWAP_MAP_MAX.
776 */
777 if (*swap_map == SWAP_MAP_MAX) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700778 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779 *swap_map = 1;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700780 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 reset_overflow = 1;
782 }
783
784 /*
785 * If a reference remains (rare), we would like to leave
786 * the page in the swap cache; but try_to_unmap could
787 * then re-duplicate the entry once we drop page lock,
788 * so we might loop indefinitely; also, that page could
789 * not be swapped out to other storage meanwhile. So:
790 * delete from cache even if there's another reference,
791 * after ensuring that the data has been saved to disk -
792 * since if the reference remains (rarer), it will be
793 * read from disk into another page. Splitting into two
794 * pages would be incorrect if swap supported "shared
795 * private" pages, but they are handled by tmpfs files.
796 *
797 * Note shmem_unuse already deleted a swappage from
798 * the swap cache, unless the move to filepage failed:
799 * in which case it left swappage in cache, lowered its
800 * swap count to pass quickly through the loops above,
801 * and now we must reincrement count to try again later.
802 */
803 if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) {
804 struct writeback_control wbc = {
805 .sync_mode = WB_SYNC_NONE,
806 };
807
808 swap_writepage(page, &wbc);
809 lock_page(page);
810 wait_on_page_writeback(page);
811 }
812 if (PageSwapCache(page)) {
813 if (shmem)
814 swap_duplicate(entry);
815 else
816 delete_from_swap_cache(page);
817 }
818
819 /*
820 * So we could skip searching mms once swap count went
821 * to 1, we did not mark any present ptes as dirty: must
822 * mark page dirty so shrink_list will preserve it.
823 */
824 SetPageDirty(page);
825 unlock_page(page);
826 page_cache_release(page);
827
828 /*
829 * Make sure that we aren't completely killing
830 * interactive performance.
831 */
832 cond_resched();
833 }
834
835 mmput(start_mm);
836 if (reset_overflow) {
837 printk(KERN_WARNING "swapoff: cleared swap entry overflow\n");
838 swap_overflow = 0;
839 }
840 return retval;
841}
842
843/*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700844 * After a successful try_to_unuse, if no swap is now in use, we know
845 * we can empty the mmlist. swap_lock must be held on entry and exit.
846 * Note that mmlist_lock nests inside swap_lock, and an mm must be
Linus Torvalds1da177e2005-04-16 15:20:36 -0700847 * added to the mmlist just after page_duplicate - before would be racy.
848 */
849static void drain_mmlist(void)
850{
851 struct list_head *p, *next;
852 unsigned int i;
853
854 for (i = 0; i < nr_swapfiles; i++)
855 if (swap_info[i].inuse_pages)
856 return;
857 spin_lock(&mmlist_lock);
858 list_for_each_safe(p, next, &init_mm.mmlist)
859 list_del_init(p);
860 spin_unlock(&mmlist_lock);
861}
862
863/*
864 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
865 * corresponds to page offset `offset'.
866 */
867sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset)
868{
869 struct swap_extent *se = sis->curr_swap_extent;
870 struct swap_extent *start_se = se;
871
872 for ( ; ; ) {
873 struct list_head *lh;
874
875 if (se->start_page <= offset &&
876 offset < (se->start_page + se->nr_pages)) {
877 return se->start_block + (offset - se->start_page);
878 }
Hugh Dickins11d31882005-09-03 15:54:34 -0700879 lh = se->list.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 if (lh == &sis->extent_list)
Hugh Dickins11d31882005-09-03 15:54:34 -0700881 lh = lh->next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882 se = list_entry(lh, struct swap_extent, list);
883 sis->curr_swap_extent = se;
884 BUG_ON(se == start_se); /* It *must* be present */
885 }
886}
887
888/*
889 * Free all of a swapdev's extent information
890 */
891static void destroy_swap_extents(struct swap_info_struct *sis)
892{
893 while (!list_empty(&sis->extent_list)) {
894 struct swap_extent *se;
895
896 se = list_entry(sis->extent_list.next,
897 struct swap_extent, list);
898 list_del(&se->list);
899 kfree(se);
900 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901}
902
903/*
904 * Add a block range (and the corresponding page range) into this swapdev's
Hugh Dickins11d31882005-09-03 15:54:34 -0700905 * extent list. The extent list is kept sorted in page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906 *
Hugh Dickins11d31882005-09-03 15:54:34 -0700907 * This function rather assumes that it is called in ascending page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 */
909static int
910add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
911 unsigned long nr_pages, sector_t start_block)
912{
913 struct swap_extent *se;
914 struct swap_extent *new_se;
915 struct list_head *lh;
916
Hugh Dickins11d31882005-09-03 15:54:34 -0700917 lh = sis->extent_list.prev; /* The highest page extent */
918 if (lh != &sis->extent_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700919 se = list_entry(lh, struct swap_extent, list);
Hugh Dickins11d31882005-09-03 15:54:34 -0700920 BUG_ON(se->start_page + se->nr_pages != start_page);
921 if (se->start_block + se->nr_pages == start_block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922 /* Merge it */
923 se->nr_pages += nr_pages;
924 return 0;
925 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700926 }
927
928 /*
929 * No merge. Insert a new extent, preserving ordering.
930 */
931 new_se = kmalloc(sizeof(*se), GFP_KERNEL);
932 if (new_se == NULL)
933 return -ENOMEM;
934 new_se->start_page = start_page;
935 new_se->nr_pages = nr_pages;
936 new_se->start_block = start_block;
937
Hugh Dickins11d31882005-09-03 15:54:34 -0700938 list_add_tail(&new_se->list, &sis->extent_list);
Hugh Dickins53092a72005-09-03 15:54:34 -0700939 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700940}
941
942/*
943 * A `swap extent' is a simple thing which maps a contiguous range of pages
944 * onto a contiguous range of disk blocks. An ordered list of swap extents
945 * is built at swapon time and is then used at swap_writepage/swap_readpage
946 * time for locating where on disk a page belongs.
947 *
948 * If the swapfile is an S_ISBLK block device, a single extent is installed.
949 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
950 * swap files identically.
951 *
952 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
953 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
954 * swapfiles are handled *identically* after swapon time.
955 *
956 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
957 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
958 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
959 * requirements, they are simply tossed out - we will never use those blocks
960 * for swapping.
961 *
Hugh Dickinsb0d9bcd2005-09-03 15:54:31 -0700962 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
Linus Torvalds1da177e2005-04-16 15:20:36 -0700963 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
964 * which will scribble on the fs.
965 *
966 * The amount of disk space which a single swap extent represents varies.
967 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
968 * extents in the list. To avoid much list walking, we cache the previous
969 * search location in `curr_swap_extent', and start new searches from there.
970 * This is extremely effective. The average number of iterations in
971 * map_swap_page() has been measured at about 0.3 per page. - akpm.
972 */
Hugh Dickins53092a72005-09-03 15:54:34 -0700973static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974{
975 struct inode *inode;
976 unsigned blocks_per_page;
977 unsigned long page_no;
978 unsigned blkbits;
979 sector_t probe_block;
980 sector_t last_block;
Hugh Dickins53092a72005-09-03 15:54:34 -0700981 sector_t lowest_block = -1;
982 sector_t highest_block = 0;
983 int nr_extents = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700984 int ret;
985
986 inode = sis->swap_file->f_mapping->host;
987 if (S_ISBLK(inode->i_mode)) {
988 ret = add_swap_extent(sis, 0, sis->max, 0);
Hugh Dickins53092a72005-09-03 15:54:34 -0700989 *span = sis->pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990 goto done;
991 }
992
993 blkbits = inode->i_blkbits;
994 blocks_per_page = PAGE_SIZE >> blkbits;
995
996 /*
997 * Map all the blocks into the extent list. This code doesn't try
998 * to be very smart.
999 */
1000 probe_block = 0;
1001 page_no = 0;
1002 last_block = i_size_read(inode) >> blkbits;
1003 while ((probe_block + blocks_per_page) <= last_block &&
1004 page_no < sis->max) {
1005 unsigned block_in_page;
1006 sector_t first_block;
1007
1008 first_block = bmap(inode, probe_block);
1009 if (first_block == 0)
1010 goto bad_bmap;
1011
1012 /*
1013 * It must be PAGE_SIZE aligned on-disk
1014 */
1015 if (first_block & (blocks_per_page - 1)) {
1016 probe_block++;
1017 goto reprobe;
1018 }
1019
1020 for (block_in_page = 1; block_in_page < blocks_per_page;
1021 block_in_page++) {
1022 sector_t block;
1023
1024 block = bmap(inode, probe_block + block_in_page);
1025 if (block == 0)
1026 goto bad_bmap;
1027 if (block != first_block + block_in_page) {
1028 /* Discontiguity */
1029 probe_block++;
1030 goto reprobe;
1031 }
1032 }
1033
Hugh Dickins53092a72005-09-03 15:54:34 -07001034 first_block >>= (PAGE_SHIFT - blkbits);
1035 if (page_no) { /* exclude the header page */
1036 if (first_block < lowest_block)
1037 lowest_block = first_block;
1038 if (first_block > highest_block)
1039 highest_block = first_block;
1040 }
1041
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042 /*
1043 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1044 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001045 ret = add_swap_extent(sis, page_no, 1, first_block);
1046 if (ret < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047 goto out;
Hugh Dickins53092a72005-09-03 15:54:34 -07001048 nr_extents += ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049 page_no++;
1050 probe_block += blocks_per_page;
1051reprobe:
1052 continue;
1053 }
Hugh Dickins53092a72005-09-03 15:54:34 -07001054 ret = nr_extents;
1055 *span = 1 + highest_block - lowest_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 if (page_no == 0)
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001057 page_no = 1; /* force Empty message */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058 sis->max = page_no;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001059 sis->pages = page_no - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060 sis->highest_bit = page_no - 1;
1061done:
1062 sis->curr_swap_extent = list_entry(sis->extent_list.prev,
1063 struct swap_extent, list);
1064 goto out;
1065bad_bmap:
1066 printk(KERN_ERR "swapon: swapfile has holes\n");
1067 ret = -EINVAL;
1068out:
1069 return ret;
1070}
1071
1072#if 0 /* We don't need this yet */
1073#include <linux/backing-dev.h>
1074int page_queue_congested(struct page *page)
1075{
1076 struct backing_dev_info *bdi;
1077
1078 BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */
1079
1080 if (PageSwapCache(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07001081 swp_entry_t entry = { .val = page_private(page) };
Linus Torvalds1da177e2005-04-16 15:20:36 -07001082 struct swap_info_struct *sis;
1083
1084 sis = get_swap_info_struct(swp_type(entry));
1085 bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info;
1086 } else
1087 bdi = page->mapping->backing_dev_info;
1088 return bdi_write_congested(bdi);
1089}
1090#endif
1091
1092asmlinkage long sys_swapoff(const char __user * specialfile)
1093{
1094 struct swap_info_struct * p = NULL;
1095 unsigned short *swap_map;
1096 struct file *swap_file, *victim;
1097 struct address_space *mapping;
1098 struct inode *inode;
1099 char * pathname;
1100 int i, type, prev;
1101 int err;
1102
1103 if (!capable(CAP_SYS_ADMIN))
1104 return -EPERM;
1105
1106 pathname = getname(specialfile);
1107 err = PTR_ERR(pathname);
1108 if (IS_ERR(pathname))
1109 goto out;
1110
1111 victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0);
1112 putname(pathname);
1113 err = PTR_ERR(victim);
1114 if (IS_ERR(victim))
1115 goto out;
1116
1117 mapping = victim->f_mapping;
1118 prev = -1;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001119 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001120 for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
1121 p = swap_info + type;
1122 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
1123 if (p->swap_file->f_mapping == mapping)
1124 break;
1125 }
1126 prev = type;
1127 }
1128 if (type < 0) {
1129 err = -EINVAL;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001130 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131 goto out_dput;
1132 }
1133 if (!security_vm_enough_memory(p->pages))
1134 vm_unacct_memory(p->pages);
1135 else {
1136 err = -ENOMEM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001137 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138 goto out_dput;
1139 }
1140 if (prev < 0) {
1141 swap_list.head = p->next;
1142 } else {
1143 swap_info[prev].next = p->next;
1144 }
1145 if (type == swap_list.next) {
1146 /* just pick something that's safe... */
1147 swap_list.next = swap_list.head;
1148 }
1149 nr_swap_pages -= p->pages;
1150 total_swap_pages -= p->pages;
1151 p->flags &= ~SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001152 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -07001153
Linus Torvalds1da177e2005-04-16 15:20:36 -07001154 current->flags |= PF_SWAPOFF;
1155 err = try_to_unuse(type);
1156 current->flags &= ~PF_SWAPOFF;
1157
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158 if (err) {
1159 /* re-insert swap space back into swap_list */
Hugh Dickins5d337b92005-09-03 15:54:41 -07001160 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001161 for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next)
1162 if (p->prio >= swap_info[i].prio)
1163 break;
1164 p->next = i;
1165 if (prev < 0)
1166 swap_list.head = swap_list.next = p - swap_info;
1167 else
1168 swap_info[prev].next = p - swap_info;
1169 nr_swap_pages += p->pages;
1170 total_swap_pages += p->pages;
1171 p->flags |= SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001172 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001173 goto out_dput;
1174 }
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001175
1176 /* wait for any unplug function to finish */
1177 down_write(&swap_unplug_sem);
1178 up_write(&swap_unplug_sem);
1179
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001180 destroy_swap_extents(p);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001181 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001182 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183 drain_mmlist();
Hugh Dickins5d337b92005-09-03 15:54:41 -07001184
1185 /* wait for anyone still in scan_swap_map */
1186 p->highest_bit = 0; /* cuts scans short */
1187 while (p->flags >= SWP_SCANNING) {
1188 spin_unlock(&swap_lock);
Nishanth Aravamudan13e4b572005-09-10 00:27:25 -07001189 schedule_timeout_uninterruptible(1);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001190 spin_lock(&swap_lock);
1191 }
1192
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193 swap_file = p->swap_file;
1194 p->swap_file = NULL;
1195 p->max = 0;
1196 swap_map = p->swap_map;
1197 p->swap_map = NULL;
1198 p->flags = 0;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001199 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001200 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201 vfree(swap_map);
1202 inode = mapping->host;
1203 if (S_ISBLK(inode->i_mode)) {
1204 struct block_device *bdev = I_BDEV(inode);
1205 set_blocksize(bdev, p->old_block_size);
1206 bd_release(bdev);
1207 } else {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001208 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209 inode->i_flags &= ~S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001210 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001211 }
1212 filp_close(swap_file, NULL);
1213 err = 0;
1214
1215out_dput:
1216 filp_close(victim, NULL);
1217out:
1218 return err;
1219}
1220
1221#ifdef CONFIG_PROC_FS
1222/* iterator */
1223static void *swap_start(struct seq_file *swap, loff_t *pos)
1224{
1225 struct swap_info_struct *ptr = swap_info;
1226 int i;
1227 loff_t l = *pos;
1228
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001229 mutex_lock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001230
1231 for (i = 0; i < nr_swapfiles; i++, ptr++) {
1232 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1233 continue;
1234 if (!l--)
1235 return ptr;
1236 }
1237
1238 return NULL;
1239}
1240
1241static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
1242{
1243 struct swap_info_struct *ptr = v;
1244 struct swap_info_struct *endptr = swap_info + nr_swapfiles;
1245
1246 for (++ptr; ptr < endptr; ptr++) {
1247 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1248 continue;
1249 ++*pos;
1250 return ptr;
1251 }
1252
1253 return NULL;
1254}
1255
1256static void swap_stop(struct seq_file *swap, void *v)
1257{
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001258 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001259}
1260
1261static int swap_show(struct seq_file *swap, void *v)
1262{
1263 struct swap_info_struct *ptr = v;
1264 struct file *file;
1265 int len;
1266
1267 if (v == swap_info)
1268 seq_puts(swap, "Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1269
1270 file = ptr->swap_file;
1271 len = seq_path(swap, file->f_vfsmnt, file->f_dentry, " \t\n\\");
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001272 seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001273 len < 40 ? 40 - len : 1, " ",
1274 S_ISBLK(file->f_dentry->d_inode->i_mode) ?
1275 "partition" : "file\t",
1276 ptr->pages << (PAGE_SHIFT - 10),
1277 ptr->inuse_pages << (PAGE_SHIFT - 10),
1278 ptr->prio);
1279 return 0;
1280}
1281
1282static struct seq_operations swaps_op = {
1283 .start = swap_start,
1284 .next = swap_next,
1285 .stop = swap_stop,
1286 .show = swap_show
1287};
1288
1289static int swaps_open(struct inode *inode, struct file *file)
1290{
1291 return seq_open(file, &swaps_op);
1292}
1293
1294static struct file_operations proc_swaps_operations = {
1295 .open = swaps_open,
1296 .read = seq_read,
1297 .llseek = seq_lseek,
1298 .release = seq_release,
1299};
1300
1301static int __init procswaps_init(void)
1302{
1303 struct proc_dir_entry *entry;
1304
1305 entry = create_proc_entry("swaps", 0, NULL);
1306 if (entry)
1307 entry->proc_fops = &proc_swaps_operations;
1308 return 0;
1309}
1310__initcall(procswaps_init);
1311#endif /* CONFIG_PROC_FS */
1312
1313/*
1314 * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
1315 *
1316 * The swapon system call
1317 */
1318asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
1319{
1320 struct swap_info_struct * p;
1321 char *name = NULL;
1322 struct block_device *bdev = NULL;
1323 struct file *swap_file = NULL;
1324 struct address_space *mapping;
1325 unsigned int type;
1326 int i, prev;
1327 int error;
1328 static int least_priority;
1329 union swap_header *swap_header = NULL;
1330 int swap_header_version;
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001331 unsigned int nr_good_pages = 0;
1332 int nr_extents = 0;
Hugh Dickins53092a72005-09-03 15:54:34 -07001333 sector_t span;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334 unsigned long maxpages = 1;
1335 int swapfilesize;
1336 unsigned short *swap_map;
1337 struct page *page = NULL;
1338 struct inode *inode = NULL;
1339 int did_down = 0;
1340
1341 if (!capable(CAP_SYS_ADMIN))
1342 return -EPERM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001343 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001344 p = swap_info;
1345 for (type = 0 ; type < nr_swapfiles ; type++,p++)
1346 if (!(p->flags & SWP_USED))
1347 break;
1348 error = -EPERM;
1349 /*
1350 * Test if adding another swap device is possible. There are
1351 * two limiting factors: 1) the number of bits for the swap
1352 * type swp_entry_t definition and 2) the number of bits for
1353 * the swap type in the swap ptes as defined by the different
1354 * architectures. To honor both limitations a swap entry
1355 * with swap offset 0 and swap type ~0UL is created, encoded
1356 * to a swap pte, decoded to a swp_entry_t again and finally
1357 * the swap type part is extracted. This will mask all bits
1358 * from the initial ~0UL that can't be encoded in either the
1359 * swp_entry_t or the architecture definition of a swap pte.
1360 */
1361 if (type > swp_type(pte_to_swp_entry(swp_entry_to_pte(swp_entry(~0UL,0))))) {
Hugh Dickins5d337b92005-09-03 15:54:41 -07001362 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363 goto out;
1364 }
1365 if (type >= nr_swapfiles)
1366 nr_swapfiles = type+1;
1367 INIT_LIST_HEAD(&p->extent_list);
1368 p->flags = SWP_USED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369 p->swap_file = NULL;
1370 p->old_block_size = 0;
1371 p->swap_map = NULL;
1372 p->lowest_bit = 0;
1373 p->highest_bit = 0;
1374 p->cluster_nr = 0;
1375 p->inuse_pages = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 p->next = -1;
1377 if (swap_flags & SWAP_FLAG_PREFER) {
1378 p->prio =
1379 (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT;
1380 } else {
1381 p->prio = --least_priority;
1382 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001383 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 name = getname(specialfile);
1385 error = PTR_ERR(name);
1386 if (IS_ERR(name)) {
1387 name = NULL;
1388 goto bad_swap_2;
1389 }
1390 swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0);
1391 error = PTR_ERR(swap_file);
1392 if (IS_ERR(swap_file)) {
1393 swap_file = NULL;
1394 goto bad_swap_2;
1395 }
1396
1397 p->swap_file = swap_file;
1398 mapping = swap_file->f_mapping;
1399 inode = mapping->host;
1400
1401 error = -EBUSY;
1402 for (i = 0; i < nr_swapfiles; i++) {
1403 struct swap_info_struct *q = &swap_info[i];
1404
1405 if (i == type || !q->swap_file)
1406 continue;
1407 if (mapping == q->swap_file->f_mapping)
1408 goto bad_swap;
1409 }
1410
1411 error = -EINVAL;
1412 if (S_ISBLK(inode->i_mode)) {
1413 bdev = I_BDEV(inode);
1414 error = bd_claim(bdev, sys_swapon);
1415 if (error < 0) {
1416 bdev = NULL;
Rob Landleyf7b3a432005-09-22 21:44:27 -07001417 error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 goto bad_swap;
1419 }
1420 p->old_block_size = block_size(bdev);
1421 error = set_blocksize(bdev, PAGE_SIZE);
1422 if (error < 0)
1423 goto bad_swap;
1424 p->bdev = bdev;
1425 } else if (S_ISREG(inode->i_mode)) {
1426 p->bdev = inode->i_sb->s_bdev;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001427 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 did_down = 1;
1429 if (IS_SWAPFILE(inode)) {
1430 error = -EBUSY;
1431 goto bad_swap;
1432 }
1433 } else {
1434 goto bad_swap;
1435 }
1436
1437 swapfilesize = i_size_read(inode) >> PAGE_SHIFT;
1438
1439 /*
1440 * Read the swap header.
1441 */
1442 if (!mapping->a_ops->readpage) {
1443 error = -EINVAL;
1444 goto bad_swap;
1445 }
1446 page = read_cache_page(mapping, 0,
1447 (filler_t *)mapping->a_ops->readpage, swap_file);
1448 if (IS_ERR(page)) {
1449 error = PTR_ERR(page);
1450 goto bad_swap;
1451 }
1452 wait_on_page_locked(page);
1453 if (!PageUptodate(page))
1454 goto bad_swap;
1455 kmap(page);
1456 swap_header = page_address(page);
1457
1458 if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
1459 swap_header_version = 1;
1460 else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
1461 swap_header_version = 2;
1462 else {
Jesper Juhle97a3112006-01-11 01:50:28 +01001463 printk(KERN_ERR "Unable to find swap-space signature\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464 error = -EINVAL;
1465 goto bad_swap;
1466 }
1467
1468 switch (swap_header_version) {
1469 case 1:
1470 printk(KERN_ERR "version 0 swap is no longer supported. "
1471 "Use mkswap -v1 %s\n", name);
1472 error = -EINVAL;
1473 goto bad_swap;
1474 case 2:
1475 /* Check the swap header's sub-version and the size of
1476 the swap file and bad block lists */
1477 if (swap_header->info.version != 1) {
1478 printk(KERN_WARNING
1479 "Unable to handle swap header version %d\n",
1480 swap_header->info.version);
1481 error = -EINVAL;
1482 goto bad_swap;
1483 }
1484
1485 p->lowest_bit = 1;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001486 p->cluster_next = 1;
1487
Linus Torvalds1da177e2005-04-16 15:20:36 -07001488 /*
1489 * Find out how many pages are allowed for a single swap
1490 * device. There are two limiting factors: 1) the number of
1491 * bits for the swap offset in the swp_entry_t type and
1492 * 2) the number of bits in the a swap pte as defined by
1493 * the different architectures. In order to find the
1494 * largest possible bit mask a swap entry with swap type 0
1495 * and swap offset ~0UL is created, encoded to a swap pte,
1496 * decoded to a swp_entry_t again and finally the swap
1497 * offset is extracted. This will mask all the bits from
1498 * the initial ~0UL mask that can't be encoded in either
1499 * the swp_entry_t or the architecture definition of a
1500 * swap pte.
1501 */
1502 maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1;
1503 if (maxpages > swap_header->info.last_page)
1504 maxpages = swap_header->info.last_page;
1505 p->highest_bit = maxpages - 1;
1506
1507 error = -EINVAL;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001508 if (!maxpages)
1509 goto bad_swap;
1510 if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
1511 goto bad_swap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512 if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
1513 goto bad_swap;
Tobias Klausercd105df2006-01-08 01:00:59 -08001514
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515 /* OK, set up the swap map and apply the bad block list */
1516 if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) {
1517 error = -ENOMEM;
1518 goto bad_swap;
1519 }
1520
1521 error = 0;
1522 memset(p->swap_map, 0, maxpages * sizeof(short));
Tobias Klausercd105df2006-01-08 01:00:59 -08001523 for (i = 0; i < swap_header->info.nr_badpages; i++) {
1524 int page_nr = swap_header->info.badpages[i];
1525 if (page_nr <= 0 || page_nr >= swap_header->info.last_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001526 error = -EINVAL;
1527 else
Tobias Klausercd105df2006-01-08 01:00:59 -08001528 p->swap_map[page_nr] = SWAP_MAP_BAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001529 }
1530 nr_good_pages = swap_header->info.last_page -
1531 swap_header->info.nr_badpages -
1532 1 /* header page */;
Tobias Klausercd105df2006-01-08 01:00:59 -08001533 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534 goto bad_swap;
1535 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001536
Linus Torvalds1da177e2005-04-16 15:20:36 -07001537 if (swapfilesize && maxpages > swapfilesize) {
1538 printk(KERN_WARNING
1539 "Swap area shorter than signature indicates\n");
1540 error = -EINVAL;
1541 goto bad_swap;
1542 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001543 if (nr_good_pages) {
1544 p->swap_map[0] = SWAP_MAP_BAD;
1545 p->max = maxpages;
1546 p->pages = nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001547 nr_extents = setup_swap_extents(p, &span);
1548 if (nr_extents < 0) {
1549 error = nr_extents;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001550 goto bad_swap;
Hugh Dickins53092a72005-09-03 15:54:34 -07001551 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001552 nr_good_pages = p->pages;
1553 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554 if (!nr_good_pages) {
1555 printk(KERN_WARNING "Empty swap-file\n");
1556 error = -EINVAL;
1557 goto bad_swap;
1558 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001560 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001561 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562 p->flags = SWP_ACTIVE;
1563 nr_swap_pages += nr_good_pages;
1564 total_swap_pages += nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001565
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001566 printk(KERN_INFO "Adding %uk swap on %s. "
Hugh Dickins53092a72005-09-03 15:54:34 -07001567 "Priority:%d extents:%d across:%lluk\n",
1568 nr_good_pages<<(PAGE_SHIFT-10), name, p->prio,
1569 nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570
1571 /* insert swap space into swap_list: */
1572 prev = -1;
1573 for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
1574 if (p->prio >= swap_info[i].prio) {
1575 break;
1576 }
1577 prev = i;
1578 }
1579 p->next = i;
1580 if (prev < 0) {
1581 swap_list.head = swap_list.next = p - swap_info;
1582 } else {
1583 swap_info[prev].next = p - swap_info;
1584 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001585 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001586 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 error = 0;
1588 goto out;
1589bad_swap:
1590 if (bdev) {
1591 set_blocksize(bdev, p->old_block_size);
1592 bd_release(bdev);
1593 }
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001594 destroy_swap_extents(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001595bad_swap_2:
Hugh Dickins5d337b92005-09-03 15:54:41 -07001596 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001597 swap_map = p->swap_map;
1598 p->swap_file = NULL;
1599 p->swap_map = NULL;
1600 p->flags = 0;
1601 if (!(swap_flags & SWAP_FLAG_PREFER))
1602 ++least_priority;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001603 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604 vfree(swap_map);
1605 if (swap_file)
1606 filp_close(swap_file, NULL);
1607out:
1608 if (page && !IS_ERR(page)) {
1609 kunmap(page);
1610 page_cache_release(page);
1611 }
1612 if (name)
1613 putname(name);
1614 if (did_down) {
1615 if (!error)
1616 inode->i_flags |= S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001617 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001618 }
1619 return error;
1620}
1621
1622void si_swapinfo(struct sysinfo *val)
1623{
1624 unsigned int i;
1625 unsigned long nr_to_be_unused = 0;
1626
Hugh Dickins5d337b92005-09-03 15:54:41 -07001627 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628 for (i = 0; i < nr_swapfiles; i++) {
1629 if (!(swap_info[i].flags & SWP_USED) ||
1630 (swap_info[i].flags & SWP_WRITEOK))
1631 continue;
1632 nr_to_be_unused += swap_info[i].inuse_pages;
1633 }
1634 val->freeswap = nr_swap_pages + nr_to_be_unused;
1635 val->totalswap = total_swap_pages + nr_to_be_unused;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001636 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637}
1638
1639/*
1640 * Verify that a swap entry is valid and increment its swap map count.
1641 *
1642 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
1643 * "permanent", but will be reclaimed by the next swapoff.
1644 */
1645int swap_duplicate(swp_entry_t entry)
1646{
1647 struct swap_info_struct * p;
1648 unsigned long offset, type;
1649 int result = 0;
1650
1651 type = swp_type(entry);
1652 if (type >= nr_swapfiles)
1653 goto bad_file;
1654 p = type + swap_info;
1655 offset = swp_offset(entry);
1656
Hugh Dickins5d337b92005-09-03 15:54:41 -07001657 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001658 if (offset < p->max && p->swap_map[offset]) {
1659 if (p->swap_map[offset] < SWAP_MAP_MAX - 1) {
1660 p->swap_map[offset]++;
1661 result = 1;
1662 } else if (p->swap_map[offset] <= SWAP_MAP_MAX) {
1663 if (swap_overflow++ < 5)
1664 printk(KERN_WARNING "swap_dup: swap entry overflow\n");
1665 p->swap_map[offset] = SWAP_MAP_MAX;
1666 result = 1;
1667 }
1668 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001669 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001670out:
1671 return result;
1672
1673bad_file:
1674 printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
1675 goto out;
1676}
1677
1678struct swap_info_struct *
1679get_swap_info_struct(unsigned type)
1680{
1681 return &swap_info[type];
1682}
1683
1684/*
Hugh Dickins5d337b92005-09-03 15:54:41 -07001685 * swap_lock prevents swap_map being freed. Don't grab an extra
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686 * reference on the swaphandle, it doesn't matter if it becomes unused.
1687 */
1688int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
1689{
1690 int ret = 0, i = 1 << page_cluster;
1691 unsigned long toff;
1692 struct swap_info_struct *swapdev = swp_type(entry) + swap_info;
1693
1694 if (!page_cluster) /* no readahead */
1695 return 0;
1696 toff = (swp_offset(entry) >> page_cluster) << page_cluster;
1697 if (!toff) /* first page is swap header */
1698 toff++, i--;
1699 *offset = toff;
1700
Hugh Dickins5d337b92005-09-03 15:54:41 -07001701 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702 do {
1703 /* Don't read-ahead past the end of the swap area */
1704 if (toff >= swapdev->max)
1705 break;
1706 /* Don't read in free or bad pages */
1707 if (!swapdev->swap_map[toff])
1708 break;
1709 if (swapdev->swap_map[toff] == SWAP_MAP_BAD)
1710 break;
1711 toff++;
1712 ret++;
1713 } while (--i);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001714 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715 return ret;
1716}