blob: cc367f7e75d87f39f27a3f4c214a9174b61e87fd [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
Rafael J. Wysockif577eb32006-03-23 02:59:59 -080048static struct swap_info_struct swap_info[MAX_SWAPFILES];
Linus Torvalds1da177e2005-04-16 15:20:36 -070049
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);
Akinobu Mita9b65ef52006-03-22 00:09:09 -0800119 si->cluster_next = offset-SWAPFILE_CLUSTER+1;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700120 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
Christoph Lameter06972122006-06-23 02:03:35 -0700398 if (is_migration_entry(entry))
399 return;
400
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401 p = swap_info_get(entry);
402 if (p) {
Nick Piggin93fac702006-03-31 02:29:56 -0800403 if (swap_entry_free(p, swp_offset(entry)) == 1) {
404 page = find_get_page(&swapper_space, entry.val);
405 if (page && unlikely(TestSetPageLocked(page))) {
406 page_cache_release(page);
407 page = NULL;
408 }
409 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700410 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 }
412 if (page) {
413 int one_user;
414
415 BUG_ON(PagePrivate(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 one_user = (page_count(page) == 2);
417 /* Only cache user (+us), or swap space full? Free it! */
Nick Piggin93fac702006-03-31 02:29:56 -0800418 /* Also recheck PageSwapCache after page is locked (above) */
419 if (PageSwapCache(page) && !PageWriteback(page) &&
420 (one_user || vm_swap_full())) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 delete_from_swap_cache(page);
422 SetPageDirty(page);
423 }
424 unlock_page(page);
425 page_cache_release(page);
426 }
427}
428
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800429#ifdef CONFIG_SOFTWARE_SUSPEND
430/*
431 * Find the swap type that corresponds to given device (if any)
432 *
433 * This is needed for software suspend and is done in such a way that inode
434 * aliasing is allowed.
435 */
436int swap_type_of(dev_t device)
437{
438 int i;
439
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800440 spin_lock(&swap_lock);
441 for (i = 0; i < nr_swapfiles; i++) {
442 struct inode *inode;
443
444 if (!(swap_info[i].flags & SWP_WRITEOK))
445 continue;
Rafael J. Wysocki6e1819d2006-03-23 03:00:03 -0800446 if (!device) {
447 spin_unlock(&swap_lock);
448 return i;
449 }
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800450 inode = swap_info->swap_file->f_dentry->d_inode;
451 if (S_ISBLK(inode->i_mode) &&
452 device == MKDEV(imajor(inode), iminor(inode))) {
453 spin_unlock(&swap_lock);
454 return i;
455 }
456 }
457 spin_unlock(&swap_lock);
458 return -ENODEV;
459}
460
461/*
462 * Return either the total number of swap pages of given type, or the number
463 * of free pages of that type (depending on @free)
464 *
465 * This is needed for software suspend
466 */
467unsigned int count_swap_pages(int type, int free)
468{
469 unsigned int n = 0;
470
471 if (type < nr_swapfiles) {
472 spin_lock(&swap_lock);
473 if (swap_info[type].flags & SWP_WRITEOK) {
474 n = swap_info[type].pages;
475 if (free)
476 n -= swap_info[type].inuse_pages;
477 }
478 spin_unlock(&swap_lock);
479 }
480 return n;
481}
482#endif
483
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484/*
Hugh Dickins72866f62005-10-29 18:15:55 -0700485 * No need to decide whether this PTE shares the swap entry with others,
486 * just let do_wp_page work it out if a write is requested later - to
487 * force COW, vm_page_prot omits write permission from any private vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488 */
489static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
490 unsigned long addr, swp_entry_t entry, struct page *page)
491{
Hugh Dickins42946212005-10-29 18:16:05 -0700492 inc_mm_counter(vma->vm_mm, anon_rss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 get_page(page);
494 set_pte_at(vma->vm_mm, addr, pte,
495 pte_mkold(mk_pte(page, vma->vm_page_prot)));
496 page_add_anon_rmap(page, vma, addr);
497 swap_free(entry);
498 /*
499 * Move the page to the active list so it is not
500 * immediately swapped out again after swapon.
501 */
502 activate_page(page);
503}
504
505static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
506 unsigned long addr, unsigned long end,
507 swp_entry_t entry, struct page *page)
508{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 pte_t swp_pte = swp_entry_to_pte(entry);
Hugh Dickins705e87c2005-10-29 18:16:27 -0700510 pte_t *pte;
511 spinlock_t *ptl;
512 int found = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513
Hugh Dickins705e87c2005-10-29 18:16:27 -0700514 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 do {
516 /*
517 * swapoff spends a _lot_ of time in this loop!
518 * Test inline before going to call unuse_pte.
519 */
520 if (unlikely(pte_same(*pte, swp_pte))) {
Hugh Dickins705e87c2005-10-29 18:16:27 -0700521 unuse_pte(vma, pte++, addr, entry, page);
522 found = 1;
523 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 }
525 } while (pte++, addr += PAGE_SIZE, addr != end);
Hugh Dickins705e87c2005-10-29 18:16:27 -0700526 pte_unmap_unlock(pte - 1, ptl);
527 return found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528}
529
530static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
531 unsigned long addr, unsigned long end,
532 swp_entry_t entry, struct page *page)
533{
534 pmd_t *pmd;
535 unsigned long next;
536
537 pmd = pmd_offset(pud, addr);
538 do {
539 next = pmd_addr_end(addr, end);
540 if (pmd_none_or_clear_bad(pmd))
541 continue;
542 if (unuse_pte_range(vma, pmd, addr, next, entry, page))
543 return 1;
544 } while (pmd++, addr = next, addr != end);
545 return 0;
546}
547
548static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
549 unsigned long addr, unsigned long end,
550 swp_entry_t entry, struct page *page)
551{
552 pud_t *pud;
553 unsigned long next;
554
555 pud = pud_offset(pgd, addr);
556 do {
557 next = pud_addr_end(addr, end);
558 if (pud_none_or_clear_bad(pud))
559 continue;
560 if (unuse_pmd_range(vma, pud, addr, next, entry, page))
561 return 1;
562 } while (pud++, addr = next, addr != end);
563 return 0;
564}
565
566static int unuse_vma(struct vm_area_struct *vma,
567 swp_entry_t entry, struct page *page)
568{
569 pgd_t *pgd;
570 unsigned long addr, end, next;
571
572 if (page->mapping) {
573 addr = page_address_in_vma(page, vma);
574 if (addr == -EFAULT)
575 return 0;
576 else
577 end = addr + PAGE_SIZE;
578 } else {
579 addr = vma->vm_start;
580 end = vma->vm_end;
581 }
582
583 pgd = pgd_offset(vma->vm_mm, addr);
584 do {
585 next = pgd_addr_end(addr, end);
586 if (pgd_none_or_clear_bad(pgd))
587 continue;
588 if (unuse_pud_range(vma, pgd, addr, next, entry, page))
589 return 1;
590 } while (pgd++, addr = next, addr != end);
591 return 0;
592}
593
594static int unuse_mm(struct mm_struct *mm,
595 swp_entry_t entry, struct page *page)
596{
597 struct vm_area_struct *vma;
598
599 if (!down_read_trylock(&mm->mmap_sem)) {
600 /*
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700601 * Activate page so shrink_cache is unlikely to unmap its
602 * ptes while lock is dropped, so swapoff can make progress.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 */
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700604 activate_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605 unlock_page(page);
606 down_read(&mm->mmap_sem);
607 lock_page(page);
608 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 for (vma = mm->mmap; vma; vma = vma->vm_next) {
610 if (vma->anon_vma && unuse_vma(vma, entry, page))
611 break;
612 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613 up_read(&mm->mmap_sem);
614 /*
615 * Currently unuse_mm cannot fail, but leave error handling
616 * at call sites for now, since we change it from time to time.
617 */
618 return 0;
619}
620
621/*
622 * Scan swap_map from current position to next entry still in use.
623 * Recycle to start on reaching the end, returning 0 when empty.
624 */
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700625static unsigned int find_next_to_unuse(struct swap_info_struct *si,
626 unsigned int prev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627{
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700628 unsigned int max = si->max;
629 unsigned int i = prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 int count;
631
632 /*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700633 * No need for swap_lock here: we're just looking
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634 * for whether an entry is in use, not modifying it; false
635 * hits are okay, and sys_swapoff() has already prevented new
Hugh Dickins5d337b92005-09-03 15:54:41 -0700636 * allocations from this area (while holding swap_lock).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637 */
638 for (;;) {
639 if (++i >= max) {
640 if (!prev) {
641 i = 0;
642 break;
643 }
644 /*
645 * No entries in use at top of swap_map,
646 * loop back to start and recheck there.
647 */
648 max = prev + 1;
649 prev = 0;
650 i = 1;
651 }
652 count = si->swap_map[i];
653 if (count && count != SWAP_MAP_BAD)
654 break;
655 }
656 return i;
657}
658
659/*
660 * We completely avoid races by reading each swap page in advance,
661 * and then search for the process using it. All the necessary
662 * page table adjustments can then be made atomically.
663 */
664static int try_to_unuse(unsigned int type)
665{
666 struct swap_info_struct * si = &swap_info[type];
667 struct mm_struct *start_mm;
668 unsigned short *swap_map;
669 unsigned short swcount;
670 struct page *page;
671 swp_entry_t entry;
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700672 unsigned int i = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 int retval = 0;
674 int reset_overflow = 0;
675 int shmem;
676
677 /*
678 * When searching mms for an entry, a good strategy is to
679 * start at the first mm we freed the previous entry from
680 * (though actually we don't notice whether we or coincidence
681 * freed the entry). Initialize this start_mm with a hold.
682 *
683 * A simpler strategy would be to start at the last mm we
684 * freed the previous entry from; but that would take less
685 * advantage of mmlist ordering, which clusters forked mms
686 * together, child after parent. If we race with dup_mmap(), we
687 * prefer to resolve parent before child, lest we miss entries
688 * duplicated after we scanned child: using last mm would invert
689 * that. Though it's only a serious concern when an overflowed
690 * swap count is reset from SWAP_MAP_MAX, preventing a rescan.
691 */
692 start_mm = &init_mm;
693 atomic_inc(&init_mm.mm_users);
694
695 /*
696 * Keep on scanning until all entries have gone. Usually,
697 * one pass through swap_map is enough, but not necessarily:
698 * there are races when an instance of an entry might be missed.
699 */
700 while ((i = find_next_to_unuse(si, i)) != 0) {
701 if (signal_pending(current)) {
702 retval = -EINTR;
703 break;
704 }
705
706 /*
707 * Get a page for the entry, using the existing swap
708 * cache page if there is one. Otherwise, get a clean
709 * page and read the swap into it.
710 */
711 swap_map = &si->swap_map[i];
712 entry = swp_entry(type, i);
713 page = read_swap_cache_async(entry, NULL, 0);
714 if (!page) {
715 /*
716 * Either swap_duplicate() failed because entry
717 * has been freed independently, and will not be
718 * reused since sys_swapoff() already disabled
719 * allocation from here, or alloc_page() failed.
720 */
721 if (!*swap_map)
722 continue;
723 retval = -ENOMEM;
724 break;
725 }
726
727 /*
728 * Don't hold on to start_mm if it looks like exiting.
729 */
730 if (atomic_read(&start_mm->mm_users) == 1) {
731 mmput(start_mm);
732 start_mm = &init_mm;
733 atomic_inc(&init_mm.mm_users);
734 }
735
736 /*
737 * Wait for and lock page. When do_swap_page races with
738 * try_to_unuse, do_swap_page can handle the fault much
739 * faster than try_to_unuse can locate the entry. This
740 * apparently redundant "wait_on_page_locked" lets try_to_unuse
741 * defer to do_swap_page in such a case - in some tests,
742 * do_swap_page and try_to_unuse repeatedly compete.
743 */
744 wait_on_page_locked(page);
745 wait_on_page_writeback(page);
746 lock_page(page);
747 wait_on_page_writeback(page);
748
749 /*
750 * Remove all references to entry.
751 * Whenever we reach init_mm, there's no address space
752 * to search, but use it as a reminder to search shmem.
753 */
754 shmem = 0;
755 swcount = *swap_map;
756 if (swcount > 1) {
757 if (start_mm == &init_mm)
758 shmem = shmem_unuse(entry, page);
759 else
760 retval = unuse_mm(start_mm, entry, page);
761 }
762 if (*swap_map > 1) {
763 int set_start_mm = (*swap_map >= swcount);
764 struct list_head *p = &start_mm->mmlist;
765 struct mm_struct *new_start_mm = start_mm;
766 struct mm_struct *prev_mm = start_mm;
767 struct mm_struct *mm;
768
769 atomic_inc(&new_start_mm->mm_users);
770 atomic_inc(&prev_mm->mm_users);
771 spin_lock(&mmlist_lock);
772 while (*swap_map > 1 && !retval &&
773 (p = p->next) != &start_mm->mmlist) {
774 mm = list_entry(p, struct mm_struct, mmlist);
Hugh Dickins70af7c52006-06-23 02:03:44 -0700775 if (!atomic_inc_not_zero(&mm->mm_users))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777 spin_unlock(&mmlist_lock);
778 mmput(prev_mm);
779 prev_mm = mm;
780
781 cond_resched();
782
783 swcount = *swap_map;
784 if (swcount <= 1)
785 ;
786 else if (mm == &init_mm) {
787 set_start_mm = 1;
788 shmem = shmem_unuse(entry, page);
789 } else
790 retval = unuse_mm(mm, entry, page);
791 if (set_start_mm && *swap_map < swcount) {
792 mmput(new_start_mm);
793 atomic_inc(&mm->mm_users);
794 new_start_mm = mm;
795 set_start_mm = 0;
796 }
797 spin_lock(&mmlist_lock);
798 }
799 spin_unlock(&mmlist_lock);
800 mmput(prev_mm);
801 mmput(start_mm);
802 start_mm = new_start_mm;
803 }
804 if (retval) {
805 unlock_page(page);
806 page_cache_release(page);
807 break;
808 }
809
810 /*
811 * How could swap count reach 0x7fff when the maximum
812 * pid is 0x7fff, and there's no way to repeat a swap
813 * page within an mm (except in shmem, where it's the
814 * shared object which takes the reference count)?
815 * We believe SWAP_MAP_MAX cannot occur in Linux 2.4.
816 *
817 * If that's wrong, then we should worry more about
818 * exit_mmap() and do_munmap() cases described above:
819 * we might be resetting SWAP_MAP_MAX too early here.
820 * We know "Undead"s can happen, they're okay, so don't
821 * report them; but do report if we reset SWAP_MAP_MAX.
822 */
823 if (*swap_map == SWAP_MAP_MAX) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700824 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825 *swap_map = 1;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700826 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827 reset_overflow = 1;
828 }
829
830 /*
831 * If a reference remains (rare), we would like to leave
832 * the page in the swap cache; but try_to_unmap could
833 * then re-duplicate the entry once we drop page lock,
834 * so we might loop indefinitely; also, that page could
835 * not be swapped out to other storage meanwhile. So:
836 * delete from cache even if there's another reference,
837 * after ensuring that the data has been saved to disk -
838 * since if the reference remains (rarer), it will be
839 * read from disk into another page. Splitting into two
840 * pages would be incorrect if swap supported "shared
841 * private" pages, but they are handled by tmpfs files.
842 *
843 * Note shmem_unuse already deleted a swappage from
844 * the swap cache, unless the move to filepage failed:
845 * in which case it left swappage in cache, lowered its
846 * swap count to pass quickly through the loops above,
847 * and now we must reincrement count to try again later.
848 */
849 if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) {
850 struct writeback_control wbc = {
851 .sync_mode = WB_SYNC_NONE,
852 };
853
854 swap_writepage(page, &wbc);
855 lock_page(page);
856 wait_on_page_writeback(page);
857 }
858 if (PageSwapCache(page)) {
859 if (shmem)
860 swap_duplicate(entry);
861 else
862 delete_from_swap_cache(page);
863 }
864
865 /*
866 * So we could skip searching mms once swap count went
867 * to 1, we did not mark any present ptes as dirty: must
868 * mark page dirty so shrink_list will preserve it.
869 */
870 SetPageDirty(page);
871 unlock_page(page);
872 page_cache_release(page);
873
874 /*
875 * Make sure that we aren't completely killing
876 * interactive performance.
877 */
878 cond_resched();
879 }
880
881 mmput(start_mm);
882 if (reset_overflow) {
883 printk(KERN_WARNING "swapoff: cleared swap entry overflow\n");
884 swap_overflow = 0;
885 }
886 return retval;
887}
888
889/*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700890 * After a successful try_to_unuse, if no swap is now in use, we know
891 * we can empty the mmlist. swap_lock must be held on entry and exit.
892 * Note that mmlist_lock nests inside swap_lock, and an mm must be
Linus Torvalds1da177e2005-04-16 15:20:36 -0700893 * added to the mmlist just after page_duplicate - before would be racy.
894 */
895static void drain_mmlist(void)
896{
897 struct list_head *p, *next;
898 unsigned int i;
899
900 for (i = 0; i < nr_swapfiles; i++)
901 if (swap_info[i].inuse_pages)
902 return;
903 spin_lock(&mmlist_lock);
904 list_for_each_safe(p, next, &init_mm.mmlist)
905 list_del_init(p);
906 spin_unlock(&mmlist_lock);
907}
908
909/*
910 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
911 * corresponds to page offset `offset'.
912 */
913sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset)
914{
915 struct swap_extent *se = sis->curr_swap_extent;
916 struct swap_extent *start_se = se;
917
918 for ( ; ; ) {
919 struct list_head *lh;
920
921 if (se->start_page <= offset &&
922 offset < (se->start_page + se->nr_pages)) {
923 return se->start_block + (offset - se->start_page);
924 }
Hugh Dickins11d31882005-09-03 15:54:34 -0700925 lh = se->list.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700926 if (lh == &sis->extent_list)
Hugh Dickins11d31882005-09-03 15:54:34 -0700927 lh = lh->next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700928 se = list_entry(lh, struct swap_extent, list);
929 sis->curr_swap_extent = se;
930 BUG_ON(se == start_se); /* It *must* be present */
931 }
932}
933
934/*
935 * Free all of a swapdev's extent information
936 */
937static void destroy_swap_extents(struct swap_info_struct *sis)
938{
939 while (!list_empty(&sis->extent_list)) {
940 struct swap_extent *se;
941
942 se = list_entry(sis->extent_list.next,
943 struct swap_extent, list);
944 list_del(&se->list);
945 kfree(se);
946 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947}
948
949/*
950 * Add a block range (and the corresponding page range) into this swapdev's
Hugh Dickins11d31882005-09-03 15:54:34 -0700951 * extent list. The extent list is kept sorted in page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952 *
Hugh Dickins11d31882005-09-03 15:54:34 -0700953 * This function rather assumes that it is called in ascending page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954 */
955static int
956add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
957 unsigned long nr_pages, sector_t start_block)
958{
959 struct swap_extent *se;
960 struct swap_extent *new_se;
961 struct list_head *lh;
962
Hugh Dickins11d31882005-09-03 15:54:34 -0700963 lh = sis->extent_list.prev; /* The highest page extent */
964 if (lh != &sis->extent_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965 se = list_entry(lh, struct swap_extent, list);
Hugh Dickins11d31882005-09-03 15:54:34 -0700966 BUG_ON(se->start_page + se->nr_pages != start_page);
967 if (se->start_block + se->nr_pages == start_block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 /* Merge it */
969 se->nr_pages += nr_pages;
970 return 0;
971 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972 }
973
974 /*
975 * No merge. Insert a new extent, preserving ordering.
976 */
977 new_se = kmalloc(sizeof(*se), GFP_KERNEL);
978 if (new_se == NULL)
979 return -ENOMEM;
980 new_se->start_page = start_page;
981 new_se->nr_pages = nr_pages;
982 new_se->start_block = start_block;
983
Hugh Dickins11d31882005-09-03 15:54:34 -0700984 list_add_tail(&new_se->list, &sis->extent_list);
Hugh Dickins53092a72005-09-03 15:54:34 -0700985 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986}
987
988/*
989 * A `swap extent' is a simple thing which maps a contiguous range of pages
990 * onto a contiguous range of disk blocks. An ordered list of swap extents
991 * is built at swapon time and is then used at swap_writepage/swap_readpage
992 * time for locating where on disk a page belongs.
993 *
994 * If the swapfile is an S_ISBLK block device, a single extent is installed.
995 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
996 * swap files identically.
997 *
998 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
999 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
1000 * swapfiles are handled *identically* after swapon time.
1001 *
1002 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
1003 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
1004 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
1005 * requirements, they are simply tossed out - we will never use those blocks
1006 * for swapping.
1007 *
Hugh Dickinsb0d9bcd2005-09-03 15:54:31 -07001008 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
1010 * which will scribble on the fs.
1011 *
1012 * The amount of disk space which a single swap extent represents varies.
1013 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
1014 * extents in the list. To avoid much list walking, we cache the previous
1015 * search location in `curr_swap_extent', and start new searches from there.
1016 * This is extremely effective. The average number of iterations in
1017 * map_swap_page() has been measured at about 0.3 per page. - akpm.
1018 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001019static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020{
1021 struct inode *inode;
1022 unsigned blocks_per_page;
1023 unsigned long page_no;
1024 unsigned blkbits;
1025 sector_t probe_block;
1026 sector_t last_block;
Hugh Dickins53092a72005-09-03 15:54:34 -07001027 sector_t lowest_block = -1;
1028 sector_t highest_block = 0;
1029 int nr_extents = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030 int ret;
1031
1032 inode = sis->swap_file->f_mapping->host;
1033 if (S_ISBLK(inode->i_mode)) {
1034 ret = add_swap_extent(sis, 0, sis->max, 0);
Hugh Dickins53092a72005-09-03 15:54:34 -07001035 *span = sis->pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036 goto done;
1037 }
1038
1039 blkbits = inode->i_blkbits;
1040 blocks_per_page = PAGE_SIZE >> blkbits;
1041
1042 /*
1043 * Map all the blocks into the extent list. This code doesn't try
1044 * to be very smart.
1045 */
1046 probe_block = 0;
1047 page_no = 0;
1048 last_block = i_size_read(inode) >> blkbits;
1049 while ((probe_block + blocks_per_page) <= last_block &&
1050 page_no < sis->max) {
1051 unsigned block_in_page;
1052 sector_t first_block;
1053
1054 first_block = bmap(inode, probe_block);
1055 if (first_block == 0)
1056 goto bad_bmap;
1057
1058 /*
1059 * It must be PAGE_SIZE aligned on-disk
1060 */
1061 if (first_block & (blocks_per_page - 1)) {
1062 probe_block++;
1063 goto reprobe;
1064 }
1065
1066 for (block_in_page = 1; block_in_page < blocks_per_page;
1067 block_in_page++) {
1068 sector_t block;
1069
1070 block = bmap(inode, probe_block + block_in_page);
1071 if (block == 0)
1072 goto bad_bmap;
1073 if (block != first_block + block_in_page) {
1074 /* Discontiguity */
1075 probe_block++;
1076 goto reprobe;
1077 }
1078 }
1079
Hugh Dickins53092a72005-09-03 15:54:34 -07001080 first_block >>= (PAGE_SHIFT - blkbits);
1081 if (page_no) { /* exclude the header page */
1082 if (first_block < lowest_block)
1083 lowest_block = first_block;
1084 if (first_block > highest_block)
1085 highest_block = first_block;
1086 }
1087
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088 /*
1089 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1090 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001091 ret = add_swap_extent(sis, page_no, 1, first_block);
1092 if (ret < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001093 goto out;
Hugh Dickins53092a72005-09-03 15:54:34 -07001094 nr_extents += ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095 page_no++;
1096 probe_block += blocks_per_page;
1097reprobe:
1098 continue;
1099 }
Hugh Dickins53092a72005-09-03 15:54:34 -07001100 ret = nr_extents;
1101 *span = 1 + highest_block - lowest_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102 if (page_no == 0)
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001103 page_no = 1; /* force Empty message */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001104 sis->max = page_no;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001105 sis->pages = page_no - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001106 sis->highest_bit = page_no - 1;
1107done:
1108 sis->curr_swap_extent = list_entry(sis->extent_list.prev,
1109 struct swap_extent, list);
1110 goto out;
1111bad_bmap:
1112 printk(KERN_ERR "swapon: swapfile has holes\n");
1113 ret = -EINVAL;
1114out:
1115 return ret;
1116}
1117
1118#if 0 /* We don't need this yet */
1119#include <linux/backing-dev.h>
1120int page_queue_congested(struct page *page)
1121{
1122 struct backing_dev_info *bdi;
1123
1124 BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */
1125
1126 if (PageSwapCache(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07001127 swp_entry_t entry = { .val = page_private(page) };
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128 struct swap_info_struct *sis;
1129
1130 sis = get_swap_info_struct(swp_type(entry));
1131 bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info;
1132 } else
1133 bdi = page->mapping->backing_dev_info;
1134 return bdi_write_congested(bdi);
1135}
1136#endif
1137
1138asmlinkage long sys_swapoff(const char __user * specialfile)
1139{
1140 struct swap_info_struct * p = NULL;
1141 unsigned short *swap_map;
1142 struct file *swap_file, *victim;
1143 struct address_space *mapping;
1144 struct inode *inode;
1145 char * pathname;
1146 int i, type, prev;
1147 int err;
1148
1149 if (!capable(CAP_SYS_ADMIN))
1150 return -EPERM;
1151
1152 pathname = getname(specialfile);
1153 err = PTR_ERR(pathname);
1154 if (IS_ERR(pathname))
1155 goto out;
1156
1157 victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0);
1158 putname(pathname);
1159 err = PTR_ERR(victim);
1160 if (IS_ERR(victim))
1161 goto out;
1162
1163 mapping = victim->f_mapping;
1164 prev = -1;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001165 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001166 for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
1167 p = swap_info + type;
1168 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
1169 if (p->swap_file->f_mapping == mapping)
1170 break;
1171 }
1172 prev = type;
1173 }
1174 if (type < 0) {
1175 err = -EINVAL;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001176 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177 goto out_dput;
1178 }
1179 if (!security_vm_enough_memory(p->pages))
1180 vm_unacct_memory(p->pages);
1181 else {
1182 err = -ENOMEM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001183 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184 goto out_dput;
1185 }
1186 if (prev < 0) {
1187 swap_list.head = p->next;
1188 } else {
1189 swap_info[prev].next = p->next;
1190 }
1191 if (type == swap_list.next) {
1192 /* just pick something that's safe... */
1193 swap_list.next = swap_list.head;
1194 }
1195 nr_swap_pages -= p->pages;
1196 total_swap_pages -= p->pages;
1197 p->flags &= ~SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001198 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -07001199
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200 current->flags |= PF_SWAPOFF;
1201 err = try_to_unuse(type);
1202 current->flags &= ~PF_SWAPOFF;
1203
Linus Torvalds1da177e2005-04-16 15:20:36 -07001204 if (err) {
1205 /* re-insert swap space back into swap_list */
Hugh Dickins5d337b92005-09-03 15:54:41 -07001206 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207 for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next)
1208 if (p->prio >= swap_info[i].prio)
1209 break;
1210 p->next = i;
1211 if (prev < 0)
1212 swap_list.head = swap_list.next = p - swap_info;
1213 else
1214 swap_info[prev].next = p - swap_info;
1215 nr_swap_pages += p->pages;
1216 total_swap_pages += p->pages;
1217 p->flags |= SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001218 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219 goto out_dput;
1220 }
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001221
1222 /* wait for any unplug function to finish */
1223 down_write(&swap_unplug_sem);
1224 up_write(&swap_unplug_sem);
1225
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001226 destroy_swap_extents(p);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001227 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001228 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001229 drain_mmlist();
Hugh Dickins5d337b92005-09-03 15:54:41 -07001230
1231 /* wait for anyone still in scan_swap_map */
1232 p->highest_bit = 0; /* cuts scans short */
1233 while (p->flags >= SWP_SCANNING) {
1234 spin_unlock(&swap_lock);
Nishanth Aravamudan13e4b572005-09-10 00:27:25 -07001235 schedule_timeout_uninterruptible(1);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001236 spin_lock(&swap_lock);
1237 }
1238
Linus Torvalds1da177e2005-04-16 15:20:36 -07001239 swap_file = p->swap_file;
1240 p->swap_file = NULL;
1241 p->max = 0;
1242 swap_map = p->swap_map;
1243 p->swap_map = NULL;
1244 p->flags = 0;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001245 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001246 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001247 vfree(swap_map);
1248 inode = mapping->host;
1249 if (S_ISBLK(inode->i_mode)) {
1250 struct block_device *bdev = I_BDEV(inode);
1251 set_blocksize(bdev, p->old_block_size);
1252 bd_release(bdev);
1253 } else {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001254 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001255 inode->i_flags &= ~S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001256 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001257 }
1258 filp_close(swap_file, NULL);
1259 err = 0;
1260
1261out_dput:
1262 filp_close(victim, NULL);
1263out:
1264 return err;
1265}
1266
1267#ifdef CONFIG_PROC_FS
1268/* iterator */
1269static void *swap_start(struct seq_file *swap, loff_t *pos)
1270{
1271 struct swap_info_struct *ptr = swap_info;
1272 int i;
1273 loff_t l = *pos;
1274
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001275 mutex_lock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276
1277 for (i = 0; i < nr_swapfiles; i++, ptr++) {
1278 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1279 continue;
1280 if (!l--)
1281 return ptr;
1282 }
1283
1284 return NULL;
1285}
1286
1287static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
1288{
1289 struct swap_info_struct *ptr = v;
1290 struct swap_info_struct *endptr = swap_info + nr_swapfiles;
1291
1292 for (++ptr; ptr < endptr; ptr++) {
1293 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1294 continue;
1295 ++*pos;
1296 return ptr;
1297 }
1298
1299 return NULL;
1300}
1301
1302static void swap_stop(struct seq_file *swap, void *v)
1303{
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001304 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001305}
1306
1307static int swap_show(struct seq_file *swap, void *v)
1308{
1309 struct swap_info_struct *ptr = v;
1310 struct file *file;
1311 int len;
1312
1313 if (v == swap_info)
1314 seq_puts(swap, "Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1315
1316 file = ptr->swap_file;
1317 len = seq_path(swap, file->f_vfsmnt, file->f_dentry, " \t\n\\");
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001318 seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319 len < 40 ? 40 - len : 1, " ",
1320 S_ISBLK(file->f_dentry->d_inode->i_mode) ?
1321 "partition" : "file\t",
1322 ptr->pages << (PAGE_SHIFT - 10),
1323 ptr->inuse_pages << (PAGE_SHIFT - 10),
1324 ptr->prio);
1325 return 0;
1326}
1327
1328static struct seq_operations swaps_op = {
1329 .start = swap_start,
1330 .next = swap_next,
1331 .stop = swap_stop,
1332 .show = swap_show
1333};
1334
1335static int swaps_open(struct inode *inode, struct file *file)
1336{
1337 return seq_open(file, &swaps_op);
1338}
1339
1340static struct file_operations proc_swaps_operations = {
1341 .open = swaps_open,
1342 .read = seq_read,
1343 .llseek = seq_lseek,
1344 .release = seq_release,
1345};
1346
1347static int __init procswaps_init(void)
1348{
1349 struct proc_dir_entry *entry;
1350
1351 entry = create_proc_entry("swaps", 0, NULL);
1352 if (entry)
1353 entry->proc_fops = &proc_swaps_operations;
1354 return 0;
1355}
1356__initcall(procswaps_init);
1357#endif /* CONFIG_PROC_FS */
1358
1359/*
1360 * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
1361 *
1362 * The swapon system call
1363 */
1364asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
1365{
1366 struct swap_info_struct * p;
1367 char *name = NULL;
1368 struct block_device *bdev = NULL;
1369 struct file *swap_file = NULL;
1370 struct address_space *mapping;
1371 unsigned int type;
1372 int i, prev;
1373 int error;
1374 static int least_priority;
1375 union swap_header *swap_header = NULL;
1376 int swap_header_version;
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001377 unsigned int nr_good_pages = 0;
1378 int nr_extents = 0;
Hugh Dickins53092a72005-09-03 15:54:34 -07001379 sector_t span;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380 unsigned long maxpages = 1;
1381 int swapfilesize;
1382 unsigned short *swap_map;
1383 struct page *page = NULL;
1384 struct inode *inode = NULL;
1385 int did_down = 0;
1386
1387 if (!capable(CAP_SYS_ADMIN))
1388 return -EPERM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001389 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 p = swap_info;
1391 for (type = 0 ; type < nr_swapfiles ; type++,p++)
1392 if (!(p->flags & SWP_USED))
1393 break;
1394 error = -EPERM;
Christoph Lameter06972122006-06-23 02:03:35 -07001395 if (type >= MAX_SWAPFILES) {
Hugh Dickins5d337b92005-09-03 15:54:41 -07001396 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397 goto out;
1398 }
1399 if (type >= nr_swapfiles)
1400 nr_swapfiles = type+1;
1401 INIT_LIST_HEAD(&p->extent_list);
1402 p->flags = SWP_USED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 p->swap_file = NULL;
1404 p->old_block_size = 0;
1405 p->swap_map = NULL;
1406 p->lowest_bit = 0;
1407 p->highest_bit = 0;
1408 p->cluster_nr = 0;
1409 p->inuse_pages = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 p->next = -1;
1411 if (swap_flags & SWAP_FLAG_PREFER) {
1412 p->prio =
1413 (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT;
1414 } else {
1415 p->prio = --least_priority;
1416 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001417 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 name = getname(specialfile);
1419 error = PTR_ERR(name);
1420 if (IS_ERR(name)) {
1421 name = NULL;
1422 goto bad_swap_2;
1423 }
1424 swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0);
1425 error = PTR_ERR(swap_file);
1426 if (IS_ERR(swap_file)) {
1427 swap_file = NULL;
1428 goto bad_swap_2;
1429 }
1430
1431 p->swap_file = swap_file;
1432 mapping = swap_file->f_mapping;
1433 inode = mapping->host;
1434
1435 error = -EBUSY;
1436 for (i = 0; i < nr_swapfiles; i++) {
1437 struct swap_info_struct *q = &swap_info[i];
1438
1439 if (i == type || !q->swap_file)
1440 continue;
1441 if (mapping == q->swap_file->f_mapping)
1442 goto bad_swap;
1443 }
1444
1445 error = -EINVAL;
1446 if (S_ISBLK(inode->i_mode)) {
1447 bdev = I_BDEV(inode);
1448 error = bd_claim(bdev, sys_swapon);
1449 if (error < 0) {
1450 bdev = NULL;
Rob Landleyf7b3a432005-09-22 21:44:27 -07001451 error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452 goto bad_swap;
1453 }
1454 p->old_block_size = block_size(bdev);
1455 error = set_blocksize(bdev, PAGE_SIZE);
1456 if (error < 0)
1457 goto bad_swap;
1458 p->bdev = bdev;
1459 } else if (S_ISREG(inode->i_mode)) {
1460 p->bdev = inode->i_sb->s_bdev;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001461 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001462 did_down = 1;
1463 if (IS_SWAPFILE(inode)) {
1464 error = -EBUSY;
1465 goto bad_swap;
1466 }
1467 } else {
1468 goto bad_swap;
1469 }
1470
1471 swapfilesize = i_size_read(inode) >> PAGE_SHIFT;
1472
1473 /*
1474 * Read the swap header.
1475 */
1476 if (!mapping->a_ops->readpage) {
1477 error = -EINVAL;
1478 goto bad_swap;
1479 }
Pekka Enberg090d2b12006-06-23 02:05:08 -07001480 page = read_mapping_page(mapping, 0, swap_file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001481 if (IS_ERR(page)) {
1482 error = PTR_ERR(page);
1483 goto bad_swap;
1484 }
1485 wait_on_page_locked(page);
1486 if (!PageUptodate(page))
1487 goto bad_swap;
1488 kmap(page);
1489 swap_header = page_address(page);
1490
1491 if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
1492 swap_header_version = 1;
1493 else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
1494 swap_header_version = 2;
1495 else {
Jesper Juhle97a3112006-01-11 01:50:28 +01001496 printk(KERN_ERR "Unable to find swap-space signature\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001497 error = -EINVAL;
1498 goto bad_swap;
1499 }
1500
1501 switch (swap_header_version) {
1502 case 1:
1503 printk(KERN_ERR "version 0 swap is no longer supported. "
1504 "Use mkswap -v1 %s\n", name);
1505 error = -EINVAL;
1506 goto bad_swap;
1507 case 2:
1508 /* Check the swap header's sub-version and the size of
1509 the swap file and bad block lists */
1510 if (swap_header->info.version != 1) {
1511 printk(KERN_WARNING
1512 "Unable to handle swap header version %d\n",
1513 swap_header->info.version);
1514 error = -EINVAL;
1515 goto bad_swap;
1516 }
1517
1518 p->lowest_bit = 1;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001519 p->cluster_next = 1;
1520
Linus Torvalds1da177e2005-04-16 15:20:36 -07001521 /*
1522 * Find out how many pages are allowed for a single swap
1523 * device. There are two limiting factors: 1) the number of
1524 * bits for the swap offset in the swp_entry_t type and
1525 * 2) the number of bits in the a swap pte as defined by
1526 * the different architectures. In order to find the
1527 * largest possible bit mask a swap entry with swap type 0
1528 * and swap offset ~0UL is created, encoded to a swap pte,
1529 * decoded to a swp_entry_t again and finally the swap
1530 * offset is extracted. This will mask all the bits from
1531 * the initial ~0UL mask that can't be encoded in either
1532 * the swp_entry_t or the architecture definition of a
1533 * swap pte.
1534 */
1535 maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1;
1536 if (maxpages > swap_header->info.last_page)
1537 maxpages = swap_header->info.last_page;
1538 p->highest_bit = maxpages - 1;
1539
1540 error = -EINVAL;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001541 if (!maxpages)
1542 goto bad_swap;
1543 if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
1544 goto bad_swap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545 if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
1546 goto bad_swap;
Tobias Klausercd105df2006-01-08 01:00:59 -08001547
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 /* OK, set up the swap map and apply the bad block list */
1549 if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) {
1550 error = -ENOMEM;
1551 goto bad_swap;
1552 }
1553
1554 error = 0;
1555 memset(p->swap_map, 0, maxpages * sizeof(short));
Tobias Klausercd105df2006-01-08 01:00:59 -08001556 for (i = 0; i < swap_header->info.nr_badpages; i++) {
1557 int page_nr = swap_header->info.badpages[i];
1558 if (page_nr <= 0 || page_nr >= swap_header->info.last_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559 error = -EINVAL;
1560 else
Tobias Klausercd105df2006-01-08 01:00:59 -08001561 p->swap_map[page_nr] = SWAP_MAP_BAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562 }
1563 nr_good_pages = swap_header->info.last_page -
1564 swap_header->info.nr_badpages -
1565 1 /* header page */;
Tobias Klausercd105df2006-01-08 01:00:59 -08001566 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001567 goto bad_swap;
1568 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001569
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570 if (swapfilesize && maxpages > swapfilesize) {
1571 printk(KERN_WARNING
1572 "Swap area shorter than signature indicates\n");
1573 error = -EINVAL;
1574 goto bad_swap;
1575 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001576 if (nr_good_pages) {
1577 p->swap_map[0] = SWAP_MAP_BAD;
1578 p->max = maxpages;
1579 p->pages = nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001580 nr_extents = setup_swap_extents(p, &span);
1581 if (nr_extents < 0) {
1582 error = nr_extents;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001583 goto bad_swap;
Hugh Dickins53092a72005-09-03 15:54:34 -07001584 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001585 nr_good_pages = p->pages;
1586 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 if (!nr_good_pages) {
1588 printk(KERN_WARNING "Empty swap-file\n");
1589 error = -EINVAL;
1590 goto bad_swap;
1591 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001592
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001593 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001594 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001595 p->flags = SWP_ACTIVE;
1596 nr_swap_pages += nr_good_pages;
1597 total_swap_pages += nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001598
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001599 printk(KERN_INFO "Adding %uk swap on %s. "
Hugh Dickins53092a72005-09-03 15:54:34 -07001600 "Priority:%d extents:%d across:%lluk\n",
1601 nr_good_pages<<(PAGE_SHIFT-10), name, p->prio,
1602 nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001603
1604 /* insert swap space into swap_list: */
1605 prev = -1;
1606 for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
1607 if (p->prio >= swap_info[i].prio) {
1608 break;
1609 }
1610 prev = i;
1611 }
1612 p->next = i;
1613 if (prev < 0) {
1614 swap_list.head = swap_list.next = p - swap_info;
1615 } else {
1616 swap_info[prev].next = p - swap_info;
1617 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001618 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001619 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001620 error = 0;
1621 goto out;
1622bad_swap:
1623 if (bdev) {
1624 set_blocksize(bdev, p->old_block_size);
1625 bd_release(bdev);
1626 }
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001627 destroy_swap_extents(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628bad_swap_2:
Hugh Dickins5d337b92005-09-03 15:54:41 -07001629 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001630 swap_map = p->swap_map;
1631 p->swap_file = NULL;
1632 p->swap_map = NULL;
1633 p->flags = 0;
1634 if (!(swap_flags & SWAP_FLAG_PREFER))
1635 ++least_priority;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001636 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 vfree(swap_map);
1638 if (swap_file)
1639 filp_close(swap_file, NULL);
1640out:
1641 if (page && !IS_ERR(page)) {
1642 kunmap(page);
1643 page_cache_release(page);
1644 }
1645 if (name)
1646 putname(name);
1647 if (did_down) {
1648 if (!error)
1649 inode->i_flags |= S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001650 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001651 }
1652 return error;
1653}
1654
1655void si_swapinfo(struct sysinfo *val)
1656{
1657 unsigned int i;
1658 unsigned long nr_to_be_unused = 0;
1659
Hugh Dickins5d337b92005-09-03 15:54:41 -07001660 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661 for (i = 0; i < nr_swapfiles; i++) {
1662 if (!(swap_info[i].flags & SWP_USED) ||
1663 (swap_info[i].flags & SWP_WRITEOK))
1664 continue;
1665 nr_to_be_unused += swap_info[i].inuse_pages;
1666 }
1667 val->freeswap = nr_swap_pages + nr_to_be_unused;
1668 val->totalswap = total_swap_pages + nr_to_be_unused;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001669 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001670}
1671
1672/*
1673 * Verify that a swap entry is valid and increment its swap map count.
1674 *
1675 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
1676 * "permanent", but will be reclaimed by the next swapoff.
1677 */
1678int swap_duplicate(swp_entry_t entry)
1679{
1680 struct swap_info_struct * p;
1681 unsigned long offset, type;
1682 int result = 0;
1683
Christoph Lameter06972122006-06-23 02:03:35 -07001684 if (is_migration_entry(entry))
1685 return 1;
1686
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687 type = swp_type(entry);
1688 if (type >= nr_swapfiles)
1689 goto bad_file;
1690 p = type + swap_info;
1691 offset = swp_offset(entry);
1692
Hugh Dickins5d337b92005-09-03 15:54:41 -07001693 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001694 if (offset < p->max && p->swap_map[offset]) {
1695 if (p->swap_map[offset] < SWAP_MAP_MAX - 1) {
1696 p->swap_map[offset]++;
1697 result = 1;
1698 } else if (p->swap_map[offset] <= SWAP_MAP_MAX) {
1699 if (swap_overflow++ < 5)
1700 printk(KERN_WARNING "swap_dup: swap entry overflow\n");
1701 p->swap_map[offset] = SWAP_MAP_MAX;
1702 result = 1;
1703 }
1704 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001705 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706out:
1707 return result;
1708
1709bad_file:
1710 printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
1711 goto out;
1712}
1713
1714struct swap_info_struct *
1715get_swap_info_struct(unsigned type)
1716{
1717 return &swap_info[type];
1718}
1719
1720/*
Hugh Dickins5d337b92005-09-03 15:54:41 -07001721 * swap_lock prevents swap_map being freed. Don't grab an extra
Linus Torvalds1da177e2005-04-16 15:20:36 -07001722 * reference on the swaphandle, it doesn't matter if it becomes unused.
1723 */
1724int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
1725{
1726 int ret = 0, i = 1 << page_cluster;
1727 unsigned long toff;
1728 struct swap_info_struct *swapdev = swp_type(entry) + swap_info;
1729
1730 if (!page_cluster) /* no readahead */
1731 return 0;
1732 toff = (swp_offset(entry) >> page_cluster) << page_cluster;
1733 if (!toff) /* first page is swap header */
1734 toff++, i--;
1735 *offset = toff;
1736
Hugh Dickins5d337b92005-09-03 15:54:41 -07001737 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001738 do {
1739 /* Don't read-ahead past the end of the swap area */
1740 if (toff >= swapdev->max)
1741 break;
1742 /* Don't read in free or bad pages */
1743 if (!swapdev->swap_map[toff])
1744 break;
1745 if (swapdev->swap_map[toff] == SWAP_MAP_BAD)
1746 break;
1747 toff++;
1748 ret++;
1749 } while (--i);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001750 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751 return ret;
1752}