blob: 39aa9d12961207ba7c537ed73da2eab54ea98dd9 [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
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
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800420#ifdef CONFIG_SOFTWARE_SUSPEND
421/*
422 * Find the swap type that corresponds to given device (if any)
423 *
424 * This is needed for software suspend and is done in such a way that inode
425 * aliasing is allowed.
426 */
427int swap_type_of(dev_t device)
428{
429 int i;
430
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800431 spin_lock(&swap_lock);
432 for (i = 0; i < nr_swapfiles; i++) {
433 struct inode *inode;
434
435 if (!(swap_info[i].flags & SWP_WRITEOK))
436 continue;
Rafael J. Wysocki6e1819d2006-03-23 03:00:03 -0800437 if (!device) {
438 spin_unlock(&swap_lock);
439 return i;
440 }
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800441 inode = swap_info->swap_file->f_dentry->d_inode;
442 if (S_ISBLK(inode->i_mode) &&
443 device == MKDEV(imajor(inode), iminor(inode))) {
444 spin_unlock(&swap_lock);
445 return i;
446 }
447 }
448 spin_unlock(&swap_lock);
449 return -ENODEV;
450}
451
452/*
453 * Return either the total number of swap pages of given type, or the number
454 * of free pages of that type (depending on @free)
455 *
456 * This is needed for software suspend
457 */
458unsigned int count_swap_pages(int type, int free)
459{
460 unsigned int n = 0;
461
462 if (type < nr_swapfiles) {
463 spin_lock(&swap_lock);
464 if (swap_info[type].flags & SWP_WRITEOK) {
465 n = swap_info[type].pages;
466 if (free)
467 n -= swap_info[type].inuse_pages;
468 }
469 spin_unlock(&swap_lock);
470 }
471 return n;
472}
473#endif
474
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475/*
Hugh Dickins72866f62005-10-29 18:15:55 -0700476 * No need to decide whether this PTE shares the swap entry with others,
477 * just let do_wp_page work it out if a write is requested later - to
478 * force COW, vm_page_prot omits write permission from any private vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479 */
480static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
481 unsigned long addr, swp_entry_t entry, struct page *page)
482{
Hugh Dickins42946212005-10-29 18:16:05 -0700483 inc_mm_counter(vma->vm_mm, anon_rss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 get_page(page);
485 set_pte_at(vma->vm_mm, addr, pte,
486 pte_mkold(mk_pte(page, vma->vm_page_prot)));
487 page_add_anon_rmap(page, vma, addr);
488 swap_free(entry);
489 /*
490 * Move the page to the active list so it is not
491 * immediately swapped out again after swapon.
492 */
493 activate_page(page);
494}
495
496static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
497 unsigned long addr, unsigned long end,
498 swp_entry_t entry, struct page *page)
499{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 pte_t swp_pte = swp_entry_to_pte(entry);
Hugh Dickins705e87c2005-10-29 18:16:27 -0700501 pte_t *pte;
502 spinlock_t *ptl;
503 int found = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504
Hugh Dickins705e87c2005-10-29 18:16:27 -0700505 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506 do {
507 /*
508 * swapoff spends a _lot_ of time in this loop!
509 * Test inline before going to call unuse_pte.
510 */
511 if (unlikely(pte_same(*pte, swp_pte))) {
Hugh Dickins705e87c2005-10-29 18:16:27 -0700512 unuse_pte(vma, pte++, addr, entry, page);
513 found = 1;
514 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 }
516 } while (pte++, addr += PAGE_SIZE, addr != end);
Hugh Dickins705e87c2005-10-29 18:16:27 -0700517 pte_unmap_unlock(pte - 1, ptl);
518 return found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519}
520
521static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
522 unsigned long addr, unsigned long end,
523 swp_entry_t entry, struct page *page)
524{
525 pmd_t *pmd;
526 unsigned long next;
527
528 pmd = pmd_offset(pud, addr);
529 do {
530 next = pmd_addr_end(addr, end);
531 if (pmd_none_or_clear_bad(pmd))
532 continue;
533 if (unuse_pte_range(vma, pmd, addr, next, entry, page))
534 return 1;
535 } while (pmd++, addr = next, addr != end);
536 return 0;
537}
538
539static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
540 unsigned long addr, unsigned long end,
541 swp_entry_t entry, struct page *page)
542{
543 pud_t *pud;
544 unsigned long next;
545
546 pud = pud_offset(pgd, addr);
547 do {
548 next = pud_addr_end(addr, end);
549 if (pud_none_or_clear_bad(pud))
550 continue;
551 if (unuse_pmd_range(vma, pud, addr, next, entry, page))
552 return 1;
553 } while (pud++, addr = next, addr != end);
554 return 0;
555}
556
557static int unuse_vma(struct vm_area_struct *vma,
558 swp_entry_t entry, struct page *page)
559{
560 pgd_t *pgd;
561 unsigned long addr, end, next;
562
563 if (page->mapping) {
564 addr = page_address_in_vma(page, vma);
565 if (addr == -EFAULT)
566 return 0;
567 else
568 end = addr + PAGE_SIZE;
569 } else {
570 addr = vma->vm_start;
571 end = vma->vm_end;
572 }
573
574 pgd = pgd_offset(vma->vm_mm, addr);
575 do {
576 next = pgd_addr_end(addr, end);
577 if (pgd_none_or_clear_bad(pgd))
578 continue;
579 if (unuse_pud_range(vma, pgd, addr, next, entry, page))
580 return 1;
581 } while (pgd++, addr = next, addr != end);
582 return 0;
583}
584
585static int unuse_mm(struct mm_struct *mm,
586 swp_entry_t entry, struct page *page)
587{
588 struct vm_area_struct *vma;
589
590 if (!down_read_trylock(&mm->mmap_sem)) {
591 /*
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700592 * Activate page so shrink_cache is unlikely to unmap its
593 * ptes while lock is dropped, so swapoff can make progress.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 */
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700595 activate_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596 unlock_page(page);
597 down_read(&mm->mmap_sem);
598 lock_page(page);
599 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600 for (vma = mm->mmap; vma; vma = vma->vm_next) {
601 if (vma->anon_vma && unuse_vma(vma, entry, page))
602 break;
603 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604 up_read(&mm->mmap_sem);
605 /*
606 * Currently unuse_mm cannot fail, but leave error handling
607 * at call sites for now, since we change it from time to time.
608 */
609 return 0;
610}
611
Christoph Lametera3351e52006-02-01 03:05:39 -0800612#ifdef CONFIG_MIGRATION
613int remove_vma_swap(struct vm_area_struct *vma, struct page *page)
614{
615 swp_entry_t entry = { .val = page_private(page) };
616
617 return unuse_vma(vma, entry, page);
618}
619#endif
620
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621/*
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);
Christoph Lameterb16664e2006-02-01 03:05:36 -0800713again:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714 page = read_swap_cache_async(entry, NULL, 0);
715 if (!page) {
716 /*
717 * Either swap_duplicate() failed because entry
718 * has been freed independently, and will not be
719 * reused since sys_swapoff() already disabled
720 * allocation from here, or alloc_page() failed.
721 */
722 if (!*swap_map)
723 continue;
724 retval = -ENOMEM;
725 break;
726 }
727
728 /*
729 * Don't hold on to start_mm if it looks like exiting.
730 */
731 if (atomic_read(&start_mm->mm_users) == 1) {
732 mmput(start_mm);
733 start_mm = &init_mm;
734 atomic_inc(&init_mm.mm_users);
735 }
736
737 /*
738 * Wait for and lock page. When do_swap_page races with
739 * try_to_unuse, do_swap_page can handle the fault much
740 * faster than try_to_unuse can locate the entry. This
741 * apparently redundant "wait_on_page_locked" lets try_to_unuse
742 * defer to do_swap_page in such a case - in some tests,
743 * do_swap_page and try_to_unuse repeatedly compete.
744 */
745 wait_on_page_locked(page);
746 wait_on_page_writeback(page);
747 lock_page(page);
Christoph Lameterb16664e2006-02-01 03:05:36 -0800748 if (!PageSwapCache(page)) {
749 /* Page migration has occured */
750 unlock_page(page);
751 page_cache_release(page);
752 goto again;
753 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754 wait_on_page_writeback(page);
755
756 /*
757 * Remove all references to entry.
758 * Whenever we reach init_mm, there's no address space
759 * to search, but use it as a reminder to search shmem.
760 */
761 shmem = 0;
762 swcount = *swap_map;
763 if (swcount > 1) {
764 if (start_mm == &init_mm)
765 shmem = shmem_unuse(entry, page);
766 else
767 retval = unuse_mm(start_mm, entry, page);
768 }
769 if (*swap_map > 1) {
770 int set_start_mm = (*swap_map >= swcount);
771 struct list_head *p = &start_mm->mmlist;
772 struct mm_struct *new_start_mm = start_mm;
773 struct mm_struct *prev_mm = start_mm;
774 struct mm_struct *mm;
775
776 atomic_inc(&new_start_mm->mm_users);
777 atomic_inc(&prev_mm->mm_users);
778 spin_lock(&mmlist_lock);
779 while (*swap_map > 1 && !retval &&
780 (p = p->next) != &start_mm->mmlist) {
781 mm = list_entry(p, struct mm_struct, mmlist);
782 if (atomic_inc_return(&mm->mm_users) == 1) {
783 atomic_dec(&mm->mm_users);
784 continue;
785 }
786 spin_unlock(&mmlist_lock);
787 mmput(prev_mm);
788 prev_mm = mm;
789
790 cond_resched();
791
792 swcount = *swap_map;
793 if (swcount <= 1)
794 ;
795 else if (mm == &init_mm) {
796 set_start_mm = 1;
797 shmem = shmem_unuse(entry, page);
798 } else
799 retval = unuse_mm(mm, entry, page);
800 if (set_start_mm && *swap_map < swcount) {
801 mmput(new_start_mm);
802 atomic_inc(&mm->mm_users);
803 new_start_mm = mm;
804 set_start_mm = 0;
805 }
806 spin_lock(&mmlist_lock);
807 }
808 spin_unlock(&mmlist_lock);
809 mmput(prev_mm);
810 mmput(start_mm);
811 start_mm = new_start_mm;
812 }
813 if (retval) {
814 unlock_page(page);
815 page_cache_release(page);
816 break;
817 }
818
819 /*
820 * How could swap count reach 0x7fff when the maximum
821 * pid is 0x7fff, and there's no way to repeat a swap
822 * page within an mm (except in shmem, where it's the
823 * shared object which takes the reference count)?
824 * We believe SWAP_MAP_MAX cannot occur in Linux 2.4.
825 *
826 * If that's wrong, then we should worry more about
827 * exit_mmap() and do_munmap() cases described above:
828 * we might be resetting SWAP_MAP_MAX too early here.
829 * We know "Undead"s can happen, they're okay, so don't
830 * report them; but do report if we reset SWAP_MAP_MAX.
831 */
832 if (*swap_map == SWAP_MAP_MAX) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700833 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700834 *swap_map = 1;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700835 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700836 reset_overflow = 1;
837 }
838
839 /*
840 * If a reference remains (rare), we would like to leave
841 * the page in the swap cache; but try_to_unmap could
842 * then re-duplicate the entry once we drop page lock,
843 * so we might loop indefinitely; also, that page could
844 * not be swapped out to other storage meanwhile. So:
845 * delete from cache even if there's another reference,
846 * after ensuring that the data has been saved to disk -
847 * since if the reference remains (rarer), it will be
848 * read from disk into another page. Splitting into two
849 * pages would be incorrect if swap supported "shared
850 * private" pages, but they are handled by tmpfs files.
851 *
852 * Note shmem_unuse already deleted a swappage from
853 * the swap cache, unless the move to filepage failed:
854 * in which case it left swappage in cache, lowered its
855 * swap count to pass quickly through the loops above,
856 * and now we must reincrement count to try again later.
857 */
858 if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) {
859 struct writeback_control wbc = {
860 .sync_mode = WB_SYNC_NONE,
861 };
862
863 swap_writepage(page, &wbc);
864 lock_page(page);
865 wait_on_page_writeback(page);
866 }
867 if (PageSwapCache(page)) {
868 if (shmem)
869 swap_duplicate(entry);
870 else
871 delete_from_swap_cache(page);
872 }
873
874 /*
875 * So we could skip searching mms once swap count went
876 * to 1, we did not mark any present ptes as dirty: must
877 * mark page dirty so shrink_list will preserve it.
878 */
879 SetPageDirty(page);
880 unlock_page(page);
881 page_cache_release(page);
882
883 /*
884 * Make sure that we aren't completely killing
885 * interactive performance.
886 */
887 cond_resched();
888 }
889
890 mmput(start_mm);
891 if (reset_overflow) {
892 printk(KERN_WARNING "swapoff: cleared swap entry overflow\n");
893 swap_overflow = 0;
894 }
895 return retval;
896}
897
898/*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700899 * After a successful try_to_unuse, if no swap is now in use, we know
900 * we can empty the mmlist. swap_lock must be held on entry and exit.
901 * Note that mmlist_lock nests inside swap_lock, and an mm must be
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902 * added to the mmlist just after page_duplicate - before would be racy.
903 */
904static void drain_mmlist(void)
905{
906 struct list_head *p, *next;
907 unsigned int i;
908
909 for (i = 0; i < nr_swapfiles; i++)
910 if (swap_info[i].inuse_pages)
911 return;
912 spin_lock(&mmlist_lock);
913 list_for_each_safe(p, next, &init_mm.mmlist)
914 list_del_init(p);
915 spin_unlock(&mmlist_lock);
916}
917
918/*
919 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
920 * corresponds to page offset `offset'.
921 */
922sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset)
923{
924 struct swap_extent *se = sis->curr_swap_extent;
925 struct swap_extent *start_se = se;
926
927 for ( ; ; ) {
928 struct list_head *lh;
929
930 if (se->start_page <= offset &&
931 offset < (se->start_page + se->nr_pages)) {
932 return se->start_block + (offset - se->start_page);
933 }
Hugh Dickins11d31882005-09-03 15:54:34 -0700934 lh = se->list.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935 if (lh == &sis->extent_list)
Hugh Dickins11d31882005-09-03 15:54:34 -0700936 lh = lh->next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700937 se = list_entry(lh, struct swap_extent, list);
938 sis->curr_swap_extent = se;
939 BUG_ON(se == start_se); /* It *must* be present */
940 }
941}
942
943/*
944 * Free all of a swapdev's extent information
945 */
946static void destroy_swap_extents(struct swap_info_struct *sis)
947{
948 while (!list_empty(&sis->extent_list)) {
949 struct swap_extent *se;
950
951 se = list_entry(sis->extent_list.next,
952 struct swap_extent, list);
953 list_del(&se->list);
954 kfree(se);
955 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956}
957
958/*
959 * Add a block range (and the corresponding page range) into this swapdev's
Hugh Dickins11d31882005-09-03 15:54:34 -0700960 * extent list. The extent list is kept sorted in page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961 *
Hugh Dickins11d31882005-09-03 15:54:34 -0700962 * This function rather assumes that it is called in ascending page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700963 */
964static int
965add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
966 unsigned long nr_pages, sector_t start_block)
967{
968 struct swap_extent *se;
969 struct swap_extent *new_se;
970 struct list_head *lh;
971
Hugh Dickins11d31882005-09-03 15:54:34 -0700972 lh = sis->extent_list.prev; /* The highest page extent */
973 if (lh != &sis->extent_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974 se = list_entry(lh, struct swap_extent, list);
Hugh Dickins11d31882005-09-03 15:54:34 -0700975 BUG_ON(se->start_page + se->nr_pages != start_page);
976 if (se->start_block + se->nr_pages == start_block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977 /* Merge it */
978 se->nr_pages += nr_pages;
979 return 0;
980 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981 }
982
983 /*
984 * No merge. Insert a new extent, preserving ordering.
985 */
986 new_se = kmalloc(sizeof(*se), GFP_KERNEL);
987 if (new_se == NULL)
988 return -ENOMEM;
989 new_se->start_page = start_page;
990 new_se->nr_pages = nr_pages;
991 new_se->start_block = start_block;
992
Hugh Dickins11d31882005-09-03 15:54:34 -0700993 list_add_tail(&new_se->list, &sis->extent_list);
Hugh Dickins53092a72005-09-03 15:54:34 -0700994 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700995}
996
997/*
998 * A `swap extent' is a simple thing which maps a contiguous range of pages
999 * onto a contiguous range of disk blocks. An ordered list of swap extents
1000 * is built at swapon time and is then used at swap_writepage/swap_readpage
1001 * time for locating where on disk a page belongs.
1002 *
1003 * If the swapfile is an S_ISBLK block device, a single extent is installed.
1004 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
1005 * swap files identically.
1006 *
1007 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
1008 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
1009 * swapfiles are handled *identically* after swapon time.
1010 *
1011 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
1012 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
1013 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
1014 * requirements, they are simply tossed out - we will never use those blocks
1015 * for swapping.
1016 *
Hugh Dickinsb0d9bcd2005-09-03 15:54:31 -07001017 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
1019 * which will scribble on the fs.
1020 *
1021 * The amount of disk space which a single swap extent represents varies.
1022 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
1023 * extents in the list. To avoid much list walking, we cache the previous
1024 * search location in `curr_swap_extent', and start new searches from there.
1025 * This is extremely effective. The average number of iterations in
1026 * map_swap_page() has been measured at about 0.3 per page. - akpm.
1027 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001028static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029{
1030 struct inode *inode;
1031 unsigned blocks_per_page;
1032 unsigned long page_no;
1033 unsigned blkbits;
1034 sector_t probe_block;
1035 sector_t last_block;
Hugh Dickins53092a72005-09-03 15:54:34 -07001036 sector_t lowest_block = -1;
1037 sector_t highest_block = 0;
1038 int nr_extents = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039 int ret;
1040
1041 inode = sis->swap_file->f_mapping->host;
1042 if (S_ISBLK(inode->i_mode)) {
1043 ret = add_swap_extent(sis, 0, sis->max, 0);
Hugh Dickins53092a72005-09-03 15:54:34 -07001044 *span = sis->pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001045 goto done;
1046 }
1047
1048 blkbits = inode->i_blkbits;
1049 blocks_per_page = PAGE_SIZE >> blkbits;
1050
1051 /*
1052 * Map all the blocks into the extent list. This code doesn't try
1053 * to be very smart.
1054 */
1055 probe_block = 0;
1056 page_no = 0;
1057 last_block = i_size_read(inode) >> blkbits;
1058 while ((probe_block + blocks_per_page) <= last_block &&
1059 page_no < sis->max) {
1060 unsigned block_in_page;
1061 sector_t first_block;
1062
1063 first_block = bmap(inode, probe_block);
1064 if (first_block == 0)
1065 goto bad_bmap;
1066
1067 /*
1068 * It must be PAGE_SIZE aligned on-disk
1069 */
1070 if (first_block & (blocks_per_page - 1)) {
1071 probe_block++;
1072 goto reprobe;
1073 }
1074
1075 for (block_in_page = 1; block_in_page < blocks_per_page;
1076 block_in_page++) {
1077 sector_t block;
1078
1079 block = bmap(inode, probe_block + block_in_page);
1080 if (block == 0)
1081 goto bad_bmap;
1082 if (block != first_block + block_in_page) {
1083 /* Discontiguity */
1084 probe_block++;
1085 goto reprobe;
1086 }
1087 }
1088
Hugh Dickins53092a72005-09-03 15:54:34 -07001089 first_block >>= (PAGE_SHIFT - blkbits);
1090 if (page_no) { /* exclude the header page */
1091 if (first_block < lowest_block)
1092 lowest_block = first_block;
1093 if (first_block > highest_block)
1094 highest_block = first_block;
1095 }
1096
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097 /*
1098 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1099 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001100 ret = add_swap_extent(sis, page_no, 1, first_block);
1101 if (ret < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102 goto out;
Hugh Dickins53092a72005-09-03 15:54:34 -07001103 nr_extents += ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001104 page_no++;
1105 probe_block += blocks_per_page;
1106reprobe:
1107 continue;
1108 }
Hugh Dickins53092a72005-09-03 15:54:34 -07001109 ret = nr_extents;
1110 *span = 1 + highest_block - lowest_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001111 if (page_no == 0)
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001112 page_no = 1; /* force Empty message */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113 sis->max = page_no;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001114 sis->pages = page_no - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001115 sis->highest_bit = page_no - 1;
1116done:
1117 sis->curr_swap_extent = list_entry(sis->extent_list.prev,
1118 struct swap_extent, list);
1119 goto out;
1120bad_bmap:
1121 printk(KERN_ERR "swapon: swapfile has holes\n");
1122 ret = -EINVAL;
1123out:
1124 return ret;
1125}
1126
1127#if 0 /* We don't need this yet */
1128#include <linux/backing-dev.h>
1129int page_queue_congested(struct page *page)
1130{
1131 struct backing_dev_info *bdi;
1132
1133 BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */
1134
1135 if (PageSwapCache(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07001136 swp_entry_t entry = { .val = page_private(page) };
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137 struct swap_info_struct *sis;
1138
1139 sis = get_swap_info_struct(swp_type(entry));
1140 bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info;
1141 } else
1142 bdi = page->mapping->backing_dev_info;
1143 return bdi_write_congested(bdi);
1144}
1145#endif
1146
1147asmlinkage long sys_swapoff(const char __user * specialfile)
1148{
1149 struct swap_info_struct * p = NULL;
1150 unsigned short *swap_map;
1151 struct file *swap_file, *victim;
1152 struct address_space *mapping;
1153 struct inode *inode;
1154 char * pathname;
1155 int i, type, prev;
1156 int err;
1157
1158 if (!capable(CAP_SYS_ADMIN))
1159 return -EPERM;
1160
1161 pathname = getname(specialfile);
1162 err = PTR_ERR(pathname);
1163 if (IS_ERR(pathname))
1164 goto out;
1165
1166 victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0);
1167 putname(pathname);
1168 err = PTR_ERR(victim);
1169 if (IS_ERR(victim))
1170 goto out;
1171
1172 mapping = victim->f_mapping;
1173 prev = -1;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001174 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175 for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
1176 p = swap_info + type;
1177 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
1178 if (p->swap_file->f_mapping == mapping)
1179 break;
1180 }
1181 prev = type;
1182 }
1183 if (type < 0) {
1184 err = -EINVAL;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001185 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186 goto out_dput;
1187 }
1188 if (!security_vm_enough_memory(p->pages))
1189 vm_unacct_memory(p->pages);
1190 else {
1191 err = -ENOMEM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001192 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193 goto out_dput;
1194 }
1195 if (prev < 0) {
1196 swap_list.head = p->next;
1197 } else {
1198 swap_info[prev].next = p->next;
1199 }
1200 if (type == swap_list.next) {
1201 /* just pick something that's safe... */
1202 swap_list.next = swap_list.head;
1203 }
1204 nr_swap_pages -= p->pages;
1205 total_swap_pages -= p->pages;
1206 p->flags &= ~SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001207 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -07001208
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209 current->flags |= PF_SWAPOFF;
1210 err = try_to_unuse(type);
1211 current->flags &= ~PF_SWAPOFF;
1212
Linus Torvalds1da177e2005-04-16 15:20:36 -07001213 if (err) {
1214 /* re-insert swap space back into swap_list */
Hugh Dickins5d337b92005-09-03 15:54:41 -07001215 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next)
1217 if (p->prio >= swap_info[i].prio)
1218 break;
1219 p->next = i;
1220 if (prev < 0)
1221 swap_list.head = swap_list.next = p - swap_info;
1222 else
1223 swap_info[prev].next = p - swap_info;
1224 nr_swap_pages += p->pages;
1225 total_swap_pages += p->pages;
1226 p->flags |= SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001227 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001228 goto out_dput;
1229 }
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001230
1231 /* wait for any unplug function to finish */
1232 down_write(&swap_unplug_sem);
1233 up_write(&swap_unplug_sem);
1234
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001235 destroy_swap_extents(p);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001236 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001237 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 drain_mmlist();
Hugh Dickins5d337b92005-09-03 15:54:41 -07001239
1240 /* wait for anyone still in scan_swap_map */
1241 p->highest_bit = 0; /* cuts scans short */
1242 while (p->flags >= SWP_SCANNING) {
1243 spin_unlock(&swap_lock);
Nishanth Aravamudan13e4b572005-09-10 00:27:25 -07001244 schedule_timeout_uninterruptible(1);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001245 spin_lock(&swap_lock);
1246 }
1247
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248 swap_file = p->swap_file;
1249 p->swap_file = NULL;
1250 p->max = 0;
1251 swap_map = p->swap_map;
1252 p->swap_map = NULL;
1253 p->flags = 0;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001254 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001255 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001256 vfree(swap_map);
1257 inode = mapping->host;
1258 if (S_ISBLK(inode->i_mode)) {
1259 struct block_device *bdev = I_BDEV(inode);
1260 set_blocksize(bdev, p->old_block_size);
1261 bd_release(bdev);
1262 } else {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001263 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264 inode->i_flags &= ~S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001265 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266 }
1267 filp_close(swap_file, NULL);
1268 err = 0;
1269
1270out_dput:
1271 filp_close(victim, NULL);
1272out:
1273 return err;
1274}
1275
1276#ifdef CONFIG_PROC_FS
1277/* iterator */
1278static void *swap_start(struct seq_file *swap, loff_t *pos)
1279{
1280 struct swap_info_struct *ptr = swap_info;
1281 int i;
1282 loff_t l = *pos;
1283
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001284 mutex_lock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285
1286 for (i = 0; i < nr_swapfiles; i++, ptr++) {
1287 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1288 continue;
1289 if (!l--)
1290 return ptr;
1291 }
1292
1293 return NULL;
1294}
1295
1296static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
1297{
1298 struct swap_info_struct *ptr = v;
1299 struct swap_info_struct *endptr = swap_info + nr_swapfiles;
1300
1301 for (++ptr; ptr < endptr; ptr++) {
1302 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1303 continue;
1304 ++*pos;
1305 return ptr;
1306 }
1307
1308 return NULL;
1309}
1310
1311static void swap_stop(struct seq_file *swap, void *v)
1312{
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001313 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001314}
1315
1316static int swap_show(struct seq_file *swap, void *v)
1317{
1318 struct swap_info_struct *ptr = v;
1319 struct file *file;
1320 int len;
1321
1322 if (v == swap_info)
1323 seq_puts(swap, "Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1324
1325 file = ptr->swap_file;
1326 len = seq_path(swap, file->f_vfsmnt, file->f_dentry, " \t\n\\");
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001327 seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328 len < 40 ? 40 - len : 1, " ",
1329 S_ISBLK(file->f_dentry->d_inode->i_mode) ?
1330 "partition" : "file\t",
1331 ptr->pages << (PAGE_SHIFT - 10),
1332 ptr->inuse_pages << (PAGE_SHIFT - 10),
1333 ptr->prio);
1334 return 0;
1335}
1336
1337static struct seq_operations swaps_op = {
1338 .start = swap_start,
1339 .next = swap_next,
1340 .stop = swap_stop,
1341 .show = swap_show
1342};
1343
1344static int swaps_open(struct inode *inode, struct file *file)
1345{
1346 return seq_open(file, &swaps_op);
1347}
1348
1349static struct file_operations proc_swaps_operations = {
1350 .open = swaps_open,
1351 .read = seq_read,
1352 .llseek = seq_lseek,
1353 .release = seq_release,
1354};
1355
1356static int __init procswaps_init(void)
1357{
1358 struct proc_dir_entry *entry;
1359
1360 entry = create_proc_entry("swaps", 0, NULL);
1361 if (entry)
1362 entry->proc_fops = &proc_swaps_operations;
1363 return 0;
1364}
1365__initcall(procswaps_init);
1366#endif /* CONFIG_PROC_FS */
1367
1368/*
1369 * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
1370 *
1371 * The swapon system call
1372 */
1373asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
1374{
1375 struct swap_info_struct * p;
1376 char *name = NULL;
1377 struct block_device *bdev = NULL;
1378 struct file *swap_file = NULL;
1379 struct address_space *mapping;
1380 unsigned int type;
1381 int i, prev;
1382 int error;
1383 static int least_priority;
1384 union swap_header *swap_header = NULL;
1385 int swap_header_version;
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001386 unsigned int nr_good_pages = 0;
1387 int nr_extents = 0;
Hugh Dickins53092a72005-09-03 15:54:34 -07001388 sector_t span;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389 unsigned long maxpages = 1;
1390 int swapfilesize;
1391 unsigned short *swap_map;
1392 struct page *page = NULL;
1393 struct inode *inode = NULL;
1394 int did_down = 0;
1395
1396 if (!capable(CAP_SYS_ADMIN))
1397 return -EPERM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001398 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 p = swap_info;
1400 for (type = 0 ; type < nr_swapfiles ; type++,p++)
1401 if (!(p->flags & SWP_USED))
1402 break;
1403 error = -EPERM;
1404 /*
1405 * Test if adding another swap device is possible. There are
1406 * two limiting factors: 1) the number of bits for the swap
1407 * type swp_entry_t definition and 2) the number of bits for
1408 * the swap type in the swap ptes as defined by the different
1409 * architectures. To honor both limitations a swap entry
1410 * with swap offset 0 and swap type ~0UL is created, encoded
1411 * to a swap pte, decoded to a swp_entry_t again and finally
1412 * the swap type part is extracted. This will mask all bits
1413 * from the initial ~0UL that can't be encoded in either the
1414 * swp_entry_t or the architecture definition of a swap pte.
1415 */
1416 if (type > swp_type(pte_to_swp_entry(swp_entry_to_pte(swp_entry(~0UL,0))))) {
Hugh Dickins5d337b92005-09-03 15:54:41 -07001417 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 goto out;
1419 }
1420 if (type >= nr_swapfiles)
1421 nr_swapfiles = type+1;
1422 INIT_LIST_HEAD(&p->extent_list);
1423 p->flags = SWP_USED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424 p->swap_file = NULL;
1425 p->old_block_size = 0;
1426 p->swap_map = NULL;
1427 p->lowest_bit = 0;
1428 p->highest_bit = 0;
1429 p->cluster_nr = 0;
1430 p->inuse_pages = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431 p->next = -1;
1432 if (swap_flags & SWAP_FLAG_PREFER) {
1433 p->prio =
1434 (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT;
1435 } else {
1436 p->prio = --least_priority;
1437 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001438 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439 name = getname(specialfile);
1440 error = PTR_ERR(name);
1441 if (IS_ERR(name)) {
1442 name = NULL;
1443 goto bad_swap_2;
1444 }
1445 swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0);
1446 error = PTR_ERR(swap_file);
1447 if (IS_ERR(swap_file)) {
1448 swap_file = NULL;
1449 goto bad_swap_2;
1450 }
1451
1452 p->swap_file = swap_file;
1453 mapping = swap_file->f_mapping;
1454 inode = mapping->host;
1455
1456 error = -EBUSY;
1457 for (i = 0; i < nr_swapfiles; i++) {
1458 struct swap_info_struct *q = &swap_info[i];
1459
1460 if (i == type || !q->swap_file)
1461 continue;
1462 if (mapping == q->swap_file->f_mapping)
1463 goto bad_swap;
1464 }
1465
1466 error = -EINVAL;
1467 if (S_ISBLK(inode->i_mode)) {
1468 bdev = I_BDEV(inode);
1469 error = bd_claim(bdev, sys_swapon);
1470 if (error < 0) {
1471 bdev = NULL;
Rob Landleyf7b3a432005-09-22 21:44:27 -07001472 error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473 goto bad_swap;
1474 }
1475 p->old_block_size = block_size(bdev);
1476 error = set_blocksize(bdev, PAGE_SIZE);
1477 if (error < 0)
1478 goto bad_swap;
1479 p->bdev = bdev;
1480 } else if (S_ISREG(inode->i_mode)) {
1481 p->bdev = inode->i_sb->s_bdev;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001482 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001483 did_down = 1;
1484 if (IS_SWAPFILE(inode)) {
1485 error = -EBUSY;
1486 goto bad_swap;
1487 }
1488 } else {
1489 goto bad_swap;
1490 }
1491
1492 swapfilesize = i_size_read(inode) >> PAGE_SHIFT;
1493
1494 /*
1495 * Read the swap header.
1496 */
1497 if (!mapping->a_ops->readpage) {
1498 error = -EINVAL;
1499 goto bad_swap;
1500 }
1501 page = read_cache_page(mapping, 0,
1502 (filler_t *)mapping->a_ops->readpage, swap_file);
1503 if (IS_ERR(page)) {
1504 error = PTR_ERR(page);
1505 goto bad_swap;
1506 }
1507 wait_on_page_locked(page);
1508 if (!PageUptodate(page))
1509 goto bad_swap;
1510 kmap(page);
1511 swap_header = page_address(page);
1512
1513 if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
1514 swap_header_version = 1;
1515 else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
1516 swap_header_version = 2;
1517 else {
Jesper Juhle97a3112006-01-11 01:50:28 +01001518 printk(KERN_ERR "Unable to find swap-space signature\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519 error = -EINVAL;
1520 goto bad_swap;
1521 }
1522
1523 switch (swap_header_version) {
1524 case 1:
1525 printk(KERN_ERR "version 0 swap is no longer supported. "
1526 "Use mkswap -v1 %s\n", name);
1527 error = -EINVAL;
1528 goto bad_swap;
1529 case 2:
1530 /* Check the swap header's sub-version and the size of
1531 the swap file and bad block lists */
1532 if (swap_header->info.version != 1) {
1533 printk(KERN_WARNING
1534 "Unable to handle swap header version %d\n",
1535 swap_header->info.version);
1536 error = -EINVAL;
1537 goto bad_swap;
1538 }
1539
1540 p->lowest_bit = 1;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001541 p->cluster_next = 1;
1542
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543 /*
1544 * Find out how many pages are allowed for a single swap
1545 * device. There are two limiting factors: 1) the number of
1546 * bits for the swap offset in the swp_entry_t type and
1547 * 2) the number of bits in the a swap pte as defined by
1548 * the different architectures. In order to find the
1549 * largest possible bit mask a swap entry with swap type 0
1550 * and swap offset ~0UL is created, encoded to a swap pte,
1551 * decoded to a swp_entry_t again and finally the swap
1552 * offset is extracted. This will mask all the bits from
1553 * the initial ~0UL mask that can't be encoded in either
1554 * the swp_entry_t or the architecture definition of a
1555 * swap pte.
1556 */
1557 maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1;
1558 if (maxpages > swap_header->info.last_page)
1559 maxpages = swap_header->info.last_page;
1560 p->highest_bit = maxpages - 1;
1561
1562 error = -EINVAL;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001563 if (!maxpages)
1564 goto bad_swap;
1565 if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
1566 goto bad_swap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001567 if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
1568 goto bad_swap;
Tobias Klausercd105df2006-01-08 01:00:59 -08001569
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570 /* OK, set up the swap map and apply the bad block list */
1571 if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) {
1572 error = -ENOMEM;
1573 goto bad_swap;
1574 }
1575
1576 error = 0;
1577 memset(p->swap_map, 0, maxpages * sizeof(short));
Tobias Klausercd105df2006-01-08 01:00:59 -08001578 for (i = 0; i < swap_header->info.nr_badpages; i++) {
1579 int page_nr = swap_header->info.badpages[i];
1580 if (page_nr <= 0 || page_nr >= swap_header->info.last_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001581 error = -EINVAL;
1582 else
Tobias Klausercd105df2006-01-08 01:00:59 -08001583 p->swap_map[page_nr] = SWAP_MAP_BAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584 }
1585 nr_good_pages = swap_header->info.last_page -
1586 swap_header->info.nr_badpages -
1587 1 /* header page */;
Tobias Klausercd105df2006-01-08 01:00:59 -08001588 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589 goto bad_swap;
1590 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001591
Linus Torvalds1da177e2005-04-16 15:20:36 -07001592 if (swapfilesize && maxpages > swapfilesize) {
1593 printk(KERN_WARNING
1594 "Swap area shorter than signature indicates\n");
1595 error = -EINVAL;
1596 goto bad_swap;
1597 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001598 if (nr_good_pages) {
1599 p->swap_map[0] = SWAP_MAP_BAD;
1600 p->max = maxpages;
1601 p->pages = nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001602 nr_extents = setup_swap_extents(p, &span);
1603 if (nr_extents < 0) {
1604 error = nr_extents;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001605 goto bad_swap;
Hugh Dickins53092a72005-09-03 15:54:34 -07001606 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001607 nr_good_pages = p->pages;
1608 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609 if (!nr_good_pages) {
1610 printk(KERN_WARNING "Empty swap-file\n");
1611 error = -EINVAL;
1612 goto bad_swap;
1613 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001615 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001616 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 p->flags = SWP_ACTIVE;
1618 nr_swap_pages += nr_good_pages;
1619 total_swap_pages += nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001620
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001621 printk(KERN_INFO "Adding %uk swap on %s. "
Hugh Dickins53092a72005-09-03 15:54:34 -07001622 "Priority:%d extents:%d across:%lluk\n",
1623 nr_good_pages<<(PAGE_SHIFT-10), name, p->prio,
1624 nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001625
1626 /* insert swap space into swap_list: */
1627 prev = -1;
1628 for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
1629 if (p->prio >= swap_info[i].prio) {
1630 break;
1631 }
1632 prev = i;
1633 }
1634 p->next = i;
1635 if (prev < 0) {
1636 swap_list.head = swap_list.next = p - swap_info;
1637 } else {
1638 swap_info[prev].next = p - swap_info;
1639 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001640 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001641 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642 error = 0;
1643 goto out;
1644bad_swap:
1645 if (bdev) {
1646 set_blocksize(bdev, p->old_block_size);
1647 bd_release(bdev);
1648 }
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001649 destroy_swap_extents(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001650bad_swap_2:
Hugh Dickins5d337b92005-09-03 15:54:41 -07001651 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652 swap_map = p->swap_map;
1653 p->swap_file = NULL;
1654 p->swap_map = NULL;
1655 p->flags = 0;
1656 if (!(swap_flags & SWAP_FLAG_PREFER))
1657 ++least_priority;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001658 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001659 vfree(swap_map);
1660 if (swap_file)
1661 filp_close(swap_file, NULL);
1662out:
1663 if (page && !IS_ERR(page)) {
1664 kunmap(page);
1665 page_cache_release(page);
1666 }
1667 if (name)
1668 putname(name);
1669 if (did_down) {
1670 if (!error)
1671 inode->i_flags |= S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001672 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673 }
1674 return error;
1675}
1676
1677void si_swapinfo(struct sysinfo *val)
1678{
1679 unsigned int i;
1680 unsigned long nr_to_be_unused = 0;
1681
Hugh Dickins5d337b92005-09-03 15:54:41 -07001682 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683 for (i = 0; i < nr_swapfiles; i++) {
1684 if (!(swap_info[i].flags & SWP_USED) ||
1685 (swap_info[i].flags & SWP_WRITEOK))
1686 continue;
1687 nr_to_be_unused += swap_info[i].inuse_pages;
1688 }
1689 val->freeswap = nr_swap_pages + nr_to_be_unused;
1690 val->totalswap = total_swap_pages + nr_to_be_unused;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001691 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692}
1693
1694/*
1695 * Verify that a swap entry is valid and increment its swap map count.
1696 *
1697 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
1698 * "permanent", but will be reclaimed by the next swapoff.
1699 */
1700int swap_duplicate(swp_entry_t entry)
1701{
1702 struct swap_info_struct * p;
1703 unsigned long offset, type;
1704 int result = 0;
1705
1706 type = swp_type(entry);
1707 if (type >= nr_swapfiles)
1708 goto bad_file;
1709 p = type + swap_info;
1710 offset = swp_offset(entry);
1711
Hugh Dickins5d337b92005-09-03 15:54:41 -07001712 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001713 if (offset < p->max && p->swap_map[offset]) {
1714 if (p->swap_map[offset] < SWAP_MAP_MAX - 1) {
1715 p->swap_map[offset]++;
1716 result = 1;
1717 } else if (p->swap_map[offset] <= SWAP_MAP_MAX) {
1718 if (swap_overflow++ < 5)
1719 printk(KERN_WARNING "swap_dup: swap entry overflow\n");
1720 p->swap_map[offset] = SWAP_MAP_MAX;
1721 result = 1;
1722 }
1723 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001724 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725out:
1726 return result;
1727
1728bad_file:
1729 printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
1730 goto out;
1731}
1732
1733struct swap_info_struct *
1734get_swap_info_struct(unsigned type)
1735{
1736 return &swap_info[type];
1737}
1738
1739/*
Hugh Dickins5d337b92005-09-03 15:54:41 -07001740 * swap_lock prevents swap_map being freed. Don't grab an extra
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741 * reference on the swaphandle, it doesn't matter if it becomes unused.
1742 */
1743int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
1744{
1745 int ret = 0, i = 1 << page_cluster;
1746 unsigned long toff;
1747 struct swap_info_struct *swapdev = swp_type(entry) + swap_info;
1748
1749 if (!page_cluster) /* no readahead */
1750 return 0;
1751 toff = (swp_offset(entry) >> page_cluster) << page_cluster;
1752 if (!toff) /* first page is swap header */
1753 toff++, i--;
1754 *offset = toff;
1755
Hugh Dickins5d337b92005-09-03 15:54:41 -07001756 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757 do {
1758 /* Don't read-ahead past the end of the swap area */
1759 if (toff >= swapdev->max)
1760 break;
1761 /* Don't read in free or bad pages */
1762 if (!swapdev->swap_map[toff])
1763 break;
1764 if (swapdev->swap_map[toff] == SWAP_MAP_BAD)
1765 break;
1766 toff++;
1767 ret++;
1768 } while (--i);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001769 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001770 return ret;
1771}