blob: 54a9f87e5162ab0a24a00e057be2fcd7f5498022 [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
Linus Torvalds1da177e2005-04-16 15:20:36 -07008#include <linux/mm.h>
9#include <linux/hugetlb.h>
10#include <linux/mman.h>
11#include <linux/slab.h>
12#include <linux/kernel_stat.h>
13#include <linux/swap.h>
14#include <linux/vmalloc.h>
15#include <linux/pagemap.h>
16#include <linux/namei.h>
17#include <linux/shm.h>
18#include <linux/blkdev.h>
19#include <linux/writeback.h>
20#include <linux/proc_fs.h>
21#include <linux/seq_file.h>
22#include <linux/init.h>
23#include <linux/module.h>
24#include <linux/rmap.h>
25#include <linux/security.h>
26#include <linux/backing-dev.h>
Ingo Molnarfc0abb12006-01-18 17:42:33 -080027#include <linux/mutex.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080028#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/syscalls.h>
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080030#include <linux/memcontrol.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
32#include <asm/pgtable.h>
33#include <asm/tlbflush.h>
34#include <linux/swapops.h>
35
Adrian Bunk7c363b82008-07-25 19:46:24 -070036static DEFINE_SPINLOCK(swap_lock);
37static unsigned int nr_swapfiles;
Linus Torvalds1da177e2005-04-16 15:20:36 -070038long total_swap_pages;
39static int swap_overflow;
Hugh Dickins78ecba02008-07-23 21:28:23 -070040static int least_priority;
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
Linus Torvalds1da177e2005-04-16 15:20:36 -070042static const char Bad_file[] = "Bad swap file entry ";
43static const char Unused_file[] = "Unused swap file entry ";
44static const char Bad_offset[] = "Bad swap offset entry ";
45static const char Unused_offset[] = "Unused swap offset entry ";
46
Adrian Bunk7c363b82008-07-25 19:46:24 -070047static struct swap_list_t swap_list = {-1, -1};
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
Rafael J. Wysockif577eb32006-03-23 02:59:59 -080049static struct swap_info_struct swap_info[MAX_SWAPFILES];
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
Ingo Molnarfc0abb12006-01-18 17:42:33 -080051static DEFINE_MUTEX(swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53/*
54 * We need this because the bdev->unplug_fn can sleep and we cannot
Hugh Dickins5d337b92005-09-03 15:54:41 -070055 * hold swap_lock while calling the unplug_fn. And swap_lock
Ingo Molnarfc0abb12006-01-18 17:42:33 -080056 * cannot be turned into a mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 */
58static DECLARE_RWSEM(swap_unplug_sem);
59
Linus Torvalds1da177e2005-04-16 15:20:36 -070060void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page)
61{
62 swp_entry_t entry;
63
64 down_read(&swap_unplug_sem);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070065 entry.val = page_private(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 if (PageSwapCache(page)) {
67 struct block_device *bdev = swap_info[swp_type(entry)].bdev;
68 struct backing_dev_info *bdi;
69
70 /*
71 * If the page is removed from swapcache from under us (with a
72 * racy try_to_unuse/swapoff) we need an additional reference
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070073 * count to avoid reading garbage from page_private(page) above.
74 * If the WARN_ON triggers during a swapoff it maybe the race
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 * condition and it's harmless. However if it triggers without
76 * swapoff it signals a problem.
77 */
78 WARN_ON(page_count(page) <= 1);
79
80 bdi = bdev->bd_inode->i_mapping->backing_dev_info;
McMullan, Jasonba323112005-05-16 21:53:40 -070081 blk_run_backing_dev(bdi, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 }
83 up_read(&swap_unplug_sem);
84}
85
Hugh Dickins048c27f2005-09-03 15:54:40 -070086#define SWAPFILE_CLUSTER 256
87#define LATENCY_LIMIT 256
88
Hugh Dickins6eb396d2005-09-03 15:54:35 -070089static inline unsigned long scan_swap_map(struct swap_info_struct *si)
Linus Torvalds1da177e2005-04-16 15:20:36 -070090{
Hugh Dickins7dfad412005-09-03 15:54:38 -070091 unsigned long offset, last_in_cluster;
Hugh Dickins048c27f2005-09-03 15:54:40 -070092 int latency_ration = LATENCY_LIMIT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070093
Hugh Dickins7dfad412005-09-03 15:54:38 -070094 /*
95 * We try to cluster swap pages by allocating them sequentially
96 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this
97 * way, however, we resort to first-free allocation, starting
98 * a new cluster. This prevents us from scattering swap pages
99 * all over the entire swap partition, so that we reduce
100 * overall disk seek times between swap pages. -- sct
101 * But we do now try to find an empty cluster. -Andrea
102 */
103
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700104 si->flags += SWP_SCANNING;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700105 if (unlikely(!si->cluster_nr)) {
106 si->cluster_nr = SWAPFILE_CLUSTER - 1;
107 if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER)
108 goto lowest;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700109 spin_unlock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700110
111 offset = si->lowest_bit;
112 last_in_cluster = offset + SWAPFILE_CLUSTER - 1;
113
114 /* Locate the first empty (unaligned) cluster */
115 for (; last_in_cluster <= si->highest_bit; offset++) {
116 if (si->swap_map[offset])
117 last_in_cluster = offset + SWAPFILE_CLUSTER;
118 else if (offset == last_in_cluster) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700119 spin_lock(&swap_lock);
Akinobu Mita9b65ef52006-03-22 00:09:09 -0800120 si->cluster_next = offset-SWAPFILE_CLUSTER+1;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700121 goto cluster;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 }
Hugh Dickins048c27f2005-09-03 15:54:40 -0700123 if (unlikely(--latency_ration < 0)) {
124 cond_resched();
125 latency_ration = LATENCY_LIMIT;
126 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700127 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700128 spin_lock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700129 goto lowest;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700131
132 si->cluster_nr--;
133cluster:
134 offset = si->cluster_next;
135 if (offset > si->highest_bit)
136lowest: offset = si->lowest_bit;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700137checks: if (!(si->flags & SWP_WRITEOK))
138 goto no_page;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700139 if (!si->highest_bit)
140 goto no_page;
141 if (!si->swap_map[offset]) {
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700142 if (offset == si->lowest_bit)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 si->lowest_bit++;
144 if (offset == si->highest_bit)
145 si->highest_bit--;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700146 si->inuse_pages++;
147 if (si->inuse_pages == si->pages) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148 si->lowest_bit = si->max;
149 si->highest_bit = 0;
150 }
151 si->swap_map[offset] = 1;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700152 si->cluster_next = offset + 1;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700153 si->flags -= SWP_SCANNING;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 return offset;
155 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700156
Hugh Dickins5d337b92005-09-03 15:54:41 -0700157 spin_unlock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700158 while (++offset <= si->highest_bit) {
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700159 if (!si->swap_map[offset]) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700160 spin_lock(&swap_lock);
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700161 goto checks;
162 }
Hugh Dickins048c27f2005-09-03 15:54:40 -0700163 if (unlikely(--latency_ration < 0)) {
164 cond_resched();
165 latency_ration = LATENCY_LIMIT;
166 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700167 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700168 spin_lock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700169 goto lowest;
170
171no_page:
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700172 si->flags -= SWP_SCANNING;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 return 0;
174}
175
176swp_entry_t get_swap_page(void)
177{
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700178 struct swap_info_struct *si;
179 pgoff_t offset;
180 int type, next;
181 int wrapped = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182
Hugh Dickins5d337b92005-09-03 15:54:41 -0700183 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 if (nr_swap_pages <= 0)
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700185 goto noswap;
186 nr_swap_pages--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700188 for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) {
189 si = swap_info + type;
190 next = si->next;
191 if (next < 0 ||
192 (!wrapped && si->prio != swap_info[next].prio)) {
193 next = swap_list.head;
194 wrapped++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 }
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700196
197 if (!si->highest_bit)
198 continue;
199 if (!(si->flags & SWP_WRITEOK))
200 continue;
201
202 swap_list.next = next;
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700203 offset = scan_swap_map(si);
Hugh Dickins5d337b92005-09-03 15:54:41 -0700204 if (offset) {
205 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700206 return swp_entry(type, offset);
Hugh Dickins5d337b92005-09-03 15:54:41 -0700207 }
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700208 next = swap_list.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 }
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700210
211 nr_swap_pages++;
212noswap:
Hugh Dickins5d337b92005-09-03 15:54:41 -0700213 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700214 return (swp_entry_t) {0};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215}
216
Rafael J. Wysocki3a291a22006-01-06 00:16:37 -0800217swp_entry_t get_swap_page_of_type(int type)
218{
219 struct swap_info_struct *si;
220 pgoff_t offset;
221
222 spin_lock(&swap_lock);
223 si = swap_info + type;
224 if (si->flags & SWP_WRITEOK) {
225 nr_swap_pages--;
226 offset = scan_swap_map(si);
227 if (offset) {
228 spin_unlock(&swap_lock);
229 return swp_entry(type, offset);
230 }
231 nr_swap_pages++;
232 }
233 spin_unlock(&swap_lock);
234 return (swp_entry_t) {0};
235}
236
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237static struct swap_info_struct * swap_info_get(swp_entry_t entry)
238{
239 struct swap_info_struct * p;
240 unsigned long offset, type;
241
242 if (!entry.val)
243 goto out;
244 type = swp_type(entry);
245 if (type >= nr_swapfiles)
246 goto bad_nofile;
247 p = & swap_info[type];
248 if (!(p->flags & SWP_USED))
249 goto bad_device;
250 offset = swp_offset(entry);
251 if (offset >= p->max)
252 goto bad_offset;
253 if (!p->swap_map[offset])
254 goto bad_free;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700255 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 return p;
257
258bad_free:
259 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val);
260 goto out;
261bad_offset:
262 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val);
263 goto out;
264bad_device:
265 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val);
266 goto out;
267bad_nofile:
268 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val);
269out:
270 return NULL;
271}
272
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273static int swap_entry_free(struct swap_info_struct *p, unsigned long offset)
274{
275 int count = p->swap_map[offset];
276
277 if (count < SWAP_MAP_MAX) {
278 count--;
279 p->swap_map[offset] = count;
280 if (!count) {
281 if (offset < p->lowest_bit)
282 p->lowest_bit = offset;
283 if (offset > p->highest_bit)
284 p->highest_bit = offset;
Hugh Dickins89d09a22005-09-03 15:54:36 -0700285 if (p->prio > swap_info[swap_list.next].prio)
286 swap_list.next = p - swap_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 nr_swap_pages++;
288 p->inuse_pages--;
289 }
290 }
291 return count;
292}
293
294/*
295 * Caller has made sure that the swapdevice corresponding to entry
296 * is still around or has not been recycled.
297 */
298void swap_free(swp_entry_t entry)
299{
300 struct swap_info_struct * p;
301
302 p = swap_info_get(entry);
303 if (p) {
304 swap_entry_free(p, swp_offset(entry));
Hugh Dickins5d337b92005-09-03 15:54:41 -0700305 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 }
307}
308
309/*
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700310 * How many references to page are currently swapped out?
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 */
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700312static inline int page_swapcount(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313{
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700314 int count = 0;
315 struct swap_info_struct *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 swp_entry_t entry;
317
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700318 entry.val = page_private(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 p = swap_info_get(entry);
320 if (p) {
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700321 /* Subtract the 1 for the swap cache itself */
322 count = p->swap_map[swp_offset(entry)] - 1;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700323 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 }
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700325 return count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326}
327
328/*
329 * We can use this swap cache entry directly
330 * if there are no other references to it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 */
332int can_share_swap_page(struct page *page)
333{
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700334 int count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700336 BUG_ON(!PageLocked(page));
337 count = page_mapcount(page);
338 if (count <= 1 && PageSwapCache(page))
339 count += page_swapcount(page);
340 return count == 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341}
342
343/*
344 * Work out if there are any other processes sharing this
345 * swap cache page. Free it if you can. Return success.
346 */
Rik van Riel68a223942008-10-18 20:26:23 -0700347static int remove_exclusive_swap_page_count(struct page *page, int count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348{
349 int retval;
350 struct swap_info_struct * p;
351 swp_entry_t entry;
352
353 BUG_ON(PagePrivate(page));
354 BUG_ON(!PageLocked(page));
355
356 if (!PageSwapCache(page))
357 return 0;
358 if (PageWriteback(page))
359 return 0;
Rik van Riel68a223942008-10-18 20:26:23 -0700360 if (page_count(page) != count) /* us + cache + ptes */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 return 0;
362
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700363 entry.val = page_private(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 p = swap_info_get(entry);
365 if (!p)
366 return 0;
367
368 /* Is the only swap cache user the cache itself? */
369 retval = 0;
370 if (p->swap_map[swp_offset(entry)] == 1) {
371 /* Recheck the page count with the swapcache lock held.. */
Nick Piggin19fd6232008-07-25 19:45:32 -0700372 spin_lock_irq(&swapper_space.tree_lock);
Rik van Riel68a223942008-10-18 20:26:23 -0700373 if ((page_count(page) == count) && !PageWriteback(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 __delete_from_swap_cache(page);
375 SetPageDirty(page);
376 retval = 1;
377 }
Nick Piggin19fd6232008-07-25 19:45:32 -0700378 spin_unlock_irq(&swapper_space.tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700380 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381
382 if (retval) {
383 swap_free(entry);
384 page_cache_release(page);
385 }
386
387 return retval;
388}
389
390/*
Rik van Riel68a223942008-10-18 20:26:23 -0700391 * Most of the time the page should have two references: one for the
392 * process and one for the swap cache.
393 */
394int remove_exclusive_swap_page(struct page *page)
395{
396 return remove_exclusive_swap_page_count(page, 2);
397}
398
399/*
400 * The pageout code holds an extra reference to the page. That raises
401 * the reference count to test for to 2 for a page that is only in the
402 * swap cache plus 1 for each process that maps the page.
403 */
404int remove_exclusive_swap_page_ref(struct page *page)
405{
406 return remove_exclusive_swap_page_count(page, 2 + page_mapcount(page));
407}
408
409/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 * Free the swap entry like above, but also try to
411 * free the page cache entry if it is the last user.
412 */
413void free_swap_and_cache(swp_entry_t entry)
414{
415 struct swap_info_struct * p;
416 struct page *page = NULL;
417
Christoph Lameter06972122006-06-23 02:03:35 -0700418 if (is_migration_entry(entry))
419 return;
420
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 p = swap_info_get(entry);
422 if (p) {
Nick Piggin93fac702006-03-31 02:29:56 -0800423 if (swap_entry_free(p, swp_offset(entry)) == 1) {
424 page = find_get_page(&swapper_space, entry.val);
Nick Piggin8413ac92008-10-18 20:26:59 -0700425 if (page && !trylock_page(page)) {
Nick Piggin93fac702006-03-31 02:29:56 -0800426 page_cache_release(page);
427 page = NULL;
428 }
429 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700430 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 }
432 if (page) {
433 int one_user;
434
435 BUG_ON(PagePrivate(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 one_user = (page_count(page) == 2);
437 /* Only cache user (+us), or swap space full? Free it! */
Nick Piggin93fac702006-03-31 02:29:56 -0800438 /* Also recheck PageSwapCache after page is locked (above) */
439 if (PageSwapCache(page) && !PageWriteback(page) &&
440 (one_user || vm_swap_full())) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 delete_from_swap_cache(page);
442 SetPageDirty(page);
443 }
444 unlock_page(page);
445 page_cache_release(page);
446 }
447}
448
Rafael J. Wysockib0cb1a12007-07-29 23:24:36 +0200449#ifdef CONFIG_HIBERNATION
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800450/*
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800451 * Find the swap type that corresponds to given device (if any).
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800452 *
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800453 * @offset - number of the PAGE_SIZE-sized block of the device, starting
454 * from 0, in which the swap header is expected to be located.
455 *
456 * This is needed for the suspend to disk (aka swsusp).
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800457 */
Rafael J. Wysocki7bf23682007-01-05 16:36:28 -0800458int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800459{
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800460 struct block_device *bdev = NULL;
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800461 int i;
462
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800463 if (device)
464 bdev = bdget(device);
465
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800466 spin_lock(&swap_lock);
467 for (i = 0; i < nr_swapfiles; i++) {
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800468 struct swap_info_struct *sis = swap_info + i;
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800469
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800470 if (!(sis->flags & SWP_WRITEOK))
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800471 continue;
Rafael J. Wysockib6b5bce2006-08-27 01:23:25 -0700472
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800473 if (!bdev) {
Rafael J. Wysocki7bf23682007-01-05 16:36:28 -0800474 if (bdev_p)
475 *bdev_p = sis->bdev;
476
Rafael J. Wysocki6e1819d2006-03-23 03:00:03 -0800477 spin_unlock(&swap_lock);
478 return i;
479 }
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800480 if (bdev == sis->bdev) {
481 struct swap_extent *se;
482
483 se = list_entry(sis->extent_list.next,
484 struct swap_extent, list);
485 if (se->start_block == offset) {
Rafael J. Wysocki7bf23682007-01-05 16:36:28 -0800486 if (bdev_p)
487 *bdev_p = sis->bdev;
488
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800489 spin_unlock(&swap_lock);
490 bdput(bdev);
491 return i;
492 }
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800493 }
494 }
495 spin_unlock(&swap_lock);
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800496 if (bdev)
497 bdput(bdev);
498
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800499 return -ENODEV;
500}
501
502/*
503 * Return either the total number of swap pages of given type, or the number
504 * of free pages of that type (depending on @free)
505 *
506 * This is needed for software suspend
507 */
508unsigned int count_swap_pages(int type, int free)
509{
510 unsigned int n = 0;
511
512 if (type < nr_swapfiles) {
513 spin_lock(&swap_lock);
514 if (swap_info[type].flags & SWP_WRITEOK) {
515 n = swap_info[type].pages;
516 if (free)
517 n -= swap_info[type].inuse_pages;
518 }
519 spin_unlock(&swap_lock);
520 }
521 return n;
522}
523#endif
524
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525/*
Hugh Dickins72866f62005-10-29 18:15:55 -0700526 * No need to decide whether this PTE shares the swap entry with others,
527 * just let do_wp_page work it out if a write is requested later - to
528 * force COW, vm_page_prot omits write permission from any private vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 */
Hugh Dickins044d66c2008-02-07 00:14:04 -0800530static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 unsigned long addr, swp_entry_t entry, struct page *page)
532{
Hugh Dickins044d66c2008-02-07 00:14:04 -0800533 spinlock_t *ptl;
534 pte_t *pte;
535 int ret = 1;
536
Balbir Singhe1a1cd52008-02-07 00:14:02 -0800537 if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL))
Hugh Dickins044d66c2008-02-07 00:14:04 -0800538 ret = -ENOMEM;
539
540 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
541 if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) {
542 if (ret > 0)
543 mem_cgroup_uncharge_page(page);
544 ret = 0;
545 goto out;
546 }
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800547
Hugh Dickins42946212005-10-29 18:16:05 -0700548 inc_mm_counter(vma->vm_mm, anon_rss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 get_page(page);
550 set_pte_at(vma->vm_mm, addr, pte,
551 pte_mkold(mk_pte(page, vma->vm_page_prot)));
552 page_add_anon_rmap(page, vma, addr);
553 swap_free(entry);
554 /*
555 * Move the page to the active list so it is not
556 * immediately swapped out again after swapon.
557 */
558 activate_page(page);
Hugh Dickins044d66c2008-02-07 00:14:04 -0800559out:
560 pte_unmap_unlock(pte, ptl);
561 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562}
563
564static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
565 unsigned long addr, unsigned long end,
566 swp_entry_t entry, struct page *page)
567{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568 pte_t swp_pte = swp_entry_to_pte(entry);
Hugh Dickins705e87c2005-10-29 18:16:27 -0700569 pte_t *pte;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800570 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571
Hugh Dickins044d66c2008-02-07 00:14:04 -0800572 /*
573 * We don't actually need pte lock while scanning for swp_pte: since
574 * we hold page lock and mmap_sem, swp_pte cannot be inserted into the
575 * page table while we're scanning; though it could get zapped, and on
576 * some architectures (e.g. x86_32 with PAE) we might catch a glimpse
577 * of unmatched parts which look like swp_pte, so unuse_pte must
578 * recheck under pte lock. Scanning without pte lock lets it be
579 * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE.
580 */
581 pte = pte_offset_map(pmd, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 do {
583 /*
584 * swapoff spends a _lot_ of time in this loop!
585 * Test inline before going to call unuse_pte.
586 */
587 if (unlikely(pte_same(*pte, swp_pte))) {
Hugh Dickins044d66c2008-02-07 00:14:04 -0800588 pte_unmap(pte);
589 ret = unuse_pte(vma, pmd, addr, entry, page);
590 if (ret)
591 goto out;
592 pte = pte_offset_map(pmd, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 }
594 } while (pte++, addr += PAGE_SIZE, addr != end);
Hugh Dickins044d66c2008-02-07 00:14:04 -0800595 pte_unmap(pte - 1);
596out:
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800597 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598}
599
600static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
601 unsigned long addr, unsigned long end,
602 swp_entry_t entry, struct page *page)
603{
604 pmd_t *pmd;
605 unsigned long next;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800606 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607
608 pmd = pmd_offset(pud, addr);
609 do {
610 next = pmd_addr_end(addr, end);
611 if (pmd_none_or_clear_bad(pmd))
612 continue;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800613 ret = unuse_pte_range(vma, pmd, addr, next, entry, page);
614 if (ret)
615 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616 } while (pmd++, addr = next, addr != end);
617 return 0;
618}
619
620static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
621 unsigned long addr, unsigned long end,
622 swp_entry_t entry, struct page *page)
623{
624 pud_t *pud;
625 unsigned long next;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800626 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627
628 pud = pud_offset(pgd, addr);
629 do {
630 next = pud_addr_end(addr, end);
631 if (pud_none_or_clear_bad(pud))
632 continue;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800633 ret = unuse_pmd_range(vma, pud, addr, next, entry, page);
634 if (ret)
635 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 } while (pud++, addr = next, addr != end);
637 return 0;
638}
639
640static int unuse_vma(struct vm_area_struct *vma,
641 swp_entry_t entry, struct page *page)
642{
643 pgd_t *pgd;
644 unsigned long addr, end, next;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800645 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700646
647 if (page->mapping) {
648 addr = page_address_in_vma(page, vma);
649 if (addr == -EFAULT)
650 return 0;
651 else
652 end = addr + PAGE_SIZE;
653 } else {
654 addr = vma->vm_start;
655 end = vma->vm_end;
656 }
657
658 pgd = pgd_offset(vma->vm_mm, addr);
659 do {
660 next = pgd_addr_end(addr, end);
661 if (pgd_none_or_clear_bad(pgd))
662 continue;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800663 ret = unuse_pud_range(vma, pgd, addr, next, entry, page);
664 if (ret)
665 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 } while (pgd++, addr = next, addr != end);
667 return 0;
668}
669
670static int unuse_mm(struct mm_struct *mm,
671 swp_entry_t entry, struct page *page)
672{
673 struct vm_area_struct *vma;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800674 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675
676 if (!down_read_trylock(&mm->mmap_sem)) {
677 /*
Fernando Luis Vazquez Cao7d034312008-07-29 22:33:41 -0700678 * Activate page so shrink_inactive_list is unlikely to unmap
679 * its ptes while lock is dropped, so swapoff can make progress.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 */
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700681 activate_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682 unlock_page(page);
683 down_read(&mm->mmap_sem);
684 lock_page(page);
685 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686 for (vma = mm->mmap; vma; vma = vma->vm_next) {
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800687 if (vma->anon_vma && (ret = unuse_vma(vma, entry, page)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688 break;
689 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 up_read(&mm->mmap_sem);
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800691 return (ret < 0)? ret: 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692}
693
694/*
695 * Scan swap_map from current position to next entry still in use.
696 * Recycle to start on reaching the end, returning 0 when empty.
697 */
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700698static unsigned int find_next_to_unuse(struct swap_info_struct *si,
699 unsigned int prev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700{
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700701 unsigned int max = si->max;
702 unsigned int i = prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 int count;
704
705 /*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700706 * No need for swap_lock here: we're just looking
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707 * for whether an entry is in use, not modifying it; false
708 * hits are okay, and sys_swapoff() has already prevented new
Hugh Dickins5d337b92005-09-03 15:54:41 -0700709 * allocations from this area (while holding swap_lock).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710 */
711 for (;;) {
712 if (++i >= max) {
713 if (!prev) {
714 i = 0;
715 break;
716 }
717 /*
718 * No entries in use at top of swap_map,
719 * loop back to start and recheck there.
720 */
721 max = prev + 1;
722 prev = 0;
723 i = 1;
724 }
725 count = si->swap_map[i];
726 if (count && count != SWAP_MAP_BAD)
727 break;
728 }
729 return i;
730}
731
732/*
733 * We completely avoid races by reading each swap page in advance,
734 * and then search for the process using it. All the necessary
735 * page table adjustments can then be made atomically.
736 */
737static int try_to_unuse(unsigned int type)
738{
739 struct swap_info_struct * si = &swap_info[type];
740 struct mm_struct *start_mm;
741 unsigned short *swap_map;
742 unsigned short swcount;
743 struct page *page;
744 swp_entry_t entry;
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700745 unsigned int i = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746 int retval = 0;
747 int reset_overflow = 0;
748 int shmem;
749
750 /*
751 * When searching mms for an entry, a good strategy is to
752 * start at the first mm we freed the previous entry from
753 * (though actually we don't notice whether we or coincidence
754 * freed the entry). Initialize this start_mm with a hold.
755 *
756 * A simpler strategy would be to start at the last mm we
757 * freed the previous entry from; but that would take less
758 * advantage of mmlist ordering, which clusters forked mms
759 * together, child after parent. If we race with dup_mmap(), we
760 * prefer to resolve parent before child, lest we miss entries
761 * duplicated after we scanned child: using last mm would invert
762 * that. Though it's only a serious concern when an overflowed
763 * swap count is reset from SWAP_MAP_MAX, preventing a rescan.
764 */
765 start_mm = &init_mm;
766 atomic_inc(&init_mm.mm_users);
767
768 /*
769 * Keep on scanning until all entries have gone. Usually,
770 * one pass through swap_map is enough, but not necessarily:
771 * there are races when an instance of an entry might be missed.
772 */
773 while ((i = find_next_to_unuse(si, i)) != 0) {
774 if (signal_pending(current)) {
775 retval = -EINTR;
776 break;
777 }
778
779 /*
780 * Get a page for the entry, using the existing swap
781 * cache page if there is one. Otherwise, get a clean
782 * page and read the swap into it.
783 */
784 swap_map = &si->swap_map[i];
785 entry = swp_entry(type, i);
Hugh Dickins02098fe2008-02-04 22:28:42 -0800786 page = read_swap_cache_async(entry,
787 GFP_HIGHUSER_MOVABLE, NULL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 if (!page) {
789 /*
790 * Either swap_duplicate() failed because entry
791 * has been freed independently, and will not be
792 * reused since sys_swapoff() already disabled
793 * allocation from here, or alloc_page() failed.
794 */
795 if (!*swap_map)
796 continue;
797 retval = -ENOMEM;
798 break;
799 }
800
801 /*
802 * Don't hold on to start_mm if it looks like exiting.
803 */
804 if (atomic_read(&start_mm->mm_users) == 1) {
805 mmput(start_mm);
806 start_mm = &init_mm;
807 atomic_inc(&init_mm.mm_users);
808 }
809
810 /*
811 * Wait for and lock page. When do_swap_page races with
812 * try_to_unuse, do_swap_page can handle the fault much
813 * faster than try_to_unuse can locate the entry. This
814 * apparently redundant "wait_on_page_locked" lets try_to_unuse
815 * defer to do_swap_page in such a case - in some tests,
816 * do_swap_page and try_to_unuse repeatedly compete.
817 */
818 wait_on_page_locked(page);
819 wait_on_page_writeback(page);
820 lock_page(page);
821 wait_on_page_writeback(page);
822
823 /*
824 * Remove all references to entry.
825 * Whenever we reach init_mm, there's no address space
826 * to search, but use it as a reminder to search shmem.
827 */
828 shmem = 0;
829 swcount = *swap_map;
830 if (swcount > 1) {
831 if (start_mm == &init_mm)
832 shmem = shmem_unuse(entry, page);
833 else
834 retval = unuse_mm(start_mm, entry, page);
835 }
836 if (*swap_map > 1) {
837 int set_start_mm = (*swap_map >= swcount);
838 struct list_head *p = &start_mm->mmlist;
839 struct mm_struct *new_start_mm = start_mm;
840 struct mm_struct *prev_mm = start_mm;
841 struct mm_struct *mm;
842
843 atomic_inc(&new_start_mm->mm_users);
844 atomic_inc(&prev_mm->mm_users);
845 spin_lock(&mmlist_lock);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800846 while (*swap_map > 1 && !retval && !shmem &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700847 (p = p->next) != &start_mm->mmlist) {
848 mm = list_entry(p, struct mm_struct, mmlist);
Hugh Dickins70af7c52006-06-23 02:03:44 -0700849 if (!atomic_inc_not_zero(&mm->mm_users))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851 spin_unlock(&mmlist_lock);
852 mmput(prev_mm);
853 prev_mm = mm;
854
855 cond_resched();
856
857 swcount = *swap_map;
858 if (swcount <= 1)
859 ;
860 else if (mm == &init_mm) {
861 set_start_mm = 1;
862 shmem = shmem_unuse(entry, page);
863 } else
864 retval = unuse_mm(mm, entry, page);
865 if (set_start_mm && *swap_map < swcount) {
866 mmput(new_start_mm);
867 atomic_inc(&mm->mm_users);
868 new_start_mm = mm;
869 set_start_mm = 0;
870 }
871 spin_lock(&mmlist_lock);
872 }
873 spin_unlock(&mmlist_lock);
874 mmput(prev_mm);
875 mmput(start_mm);
876 start_mm = new_start_mm;
877 }
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800878 if (shmem) {
879 /* page has already been unlocked and released */
880 if (shmem > 0)
881 continue;
882 retval = shmem;
883 break;
884 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885 if (retval) {
886 unlock_page(page);
887 page_cache_release(page);
888 break;
889 }
890
891 /*
892 * How could swap count reach 0x7fff when the maximum
893 * pid is 0x7fff, and there's no way to repeat a swap
894 * page within an mm (except in shmem, where it's the
895 * shared object which takes the reference count)?
896 * We believe SWAP_MAP_MAX cannot occur in Linux 2.4.
897 *
898 * If that's wrong, then we should worry more about
899 * exit_mmap() and do_munmap() cases described above:
900 * we might be resetting SWAP_MAP_MAX too early here.
901 * We know "Undead"s can happen, they're okay, so don't
902 * report them; but do report if we reset SWAP_MAP_MAX.
903 */
904 if (*swap_map == SWAP_MAP_MAX) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700905 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906 *swap_map = 1;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700907 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 reset_overflow = 1;
909 }
910
911 /*
912 * If a reference remains (rare), we would like to leave
913 * the page in the swap cache; but try_to_unmap could
914 * then re-duplicate the entry once we drop page lock,
915 * so we might loop indefinitely; also, that page could
916 * not be swapped out to other storage meanwhile. So:
917 * delete from cache even if there's another reference,
918 * after ensuring that the data has been saved to disk -
919 * since if the reference remains (rarer), it will be
920 * read from disk into another page. Splitting into two
921 * pages would be incorrect if swap supported "shared
922 * private" pages, but they are handled by tmpfs files.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923 */
924 if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) {
925 struct writeback_control wbc = {
926 .sync_mode = WB_SYNC_NONE,
927 };
928
929 swap_writepage(page, &wbc);
930 lock_page(page);
931 wait_on_page_writeback(page);
932 }
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800933 if (PageSwapCache(page))
934 delete_from_swap_cache(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935
936 /*
937 * So we could skip searching mms once swap count went
938 * to 1, we did not mark any present ptes as dirty: must
Anderson Briglia2706a1b2007-07-15 23:38:09 -0700939 * mark page dirty so shrink_page_list will preserve it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700940 */
941 SetPageDirty(page);
942 unlock_page(page);
943 page_cache_release(page);
944
945 /*
946 * Make sure that we aren't completely killing
947 * interactive performance.
948 */
949 cond_resched();
950 }
951
952 mmput(start_mm);
953 if (reset_overflow) {
954 printk(KERN_WARNING "swapoff: cleared swap entry overflow\n");
955 swap_overflow = 0;
956 }
957 return retval;
958}
959
960/*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700961 * After a successful try_to_unuse, if no swap is now in use, we know
962 * we can empty the mmlist. swap_lock must be held on entry and exit.
963 * Note that mmlist_lock nests inside swap_lock, and an mm must be
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964 * added to the mmlist just after page_duplicate - before would be racy.
965 */
966static void drain_mmlist(void)
967{
968 struct list_head *p, *next;
969 unsigned int i;
970
971 for (i = 0; i < nr_swapfiles; i++)
972 if (swap_info[i].inuse_pages)
973 return;
974 spin_lock(&mmlist_lock);
975 list_for_each_safe(p, next, &init_mm.mmlist)
976 list_del_init(p);
977 spin_unlock(&mmlist_lock);
978}
979
980/*
981 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
982 * corresponds to page offset `offset'.
983 */
984sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset)
985{
986 struct swap_extent *se = sis->curr_swap_extent;
987 struct swap_extent *start_se = se;
988
989 for ( ; ; ) {
990 struct list_head *lh;
991
992 if (se->start_page <= offset &&
993 offset < (se->start_page + se->nr_pages)) {
994 return se->start_block + (offset - se->start_page);
995 }
Hugh Dickins11d31882005-09-03 15:54:34 -0700996 lh = se->list.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997 if (lh == &sis->extent_list)
Hugh Dickins11d31882005-09-03 15:54:34 -0700998 lh = lh->next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999 se = list_entry(lh, struct swap_extent, list);
1000 sis->curr_swap_extent = se;
1001 BUG_ON(se == start_se); /* It *must* be present */
1002 }
1003}
1004
Rafael J. Wysockib0cb1a12007-07-29 23:24:36 +02001005#ifdef CONFIG_HIBERNATION
Rafael J. Wysocki3aef83e2006-12-06 20:34:10 -08001006/*
1007 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
1008 * corresponding to given index in swap_info (swap type).
1009 */
1010sector_t swapdev_block(int swap_type, pgoff_t offset)
1011{
1012 struct swap_info_struct *sis;
1013
1014 if (swap_type >= nr_swapfiles)
1015 return 0;
1016
1017 sis = swap_info + swap_type;
1018 return (sis->flags & SWP_WRITEOK) ? map_swap_page(sis, offset) : 0;
1019}
Rafael J. Wysockib0cb1a12007-07-29 23:24:36 +02001020#endif /* CONFIG_HIBERNATION */
Rafael J. Wysocki3aef83e2006-12-06 20:34:10 -08001021
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022/*
1023 * Free all of a swapdev's extent information
1024 */
1025static void destroy_swap_extents(struct swap_info_struct *sis)
1026{
1027 while (!list_empty(&sis->extent_list)) {
1028 struct swap_extent *se;
1029
1030 se = list_entry(sis->extent_list.next,
1031 struct swap_extent, list);
1032 list_del(&se->list);
1033 kfree(se);
1034 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035}
1036
1037/*
1038 * Add a block range (and the corresponding page range) into this swapdev's
Hugh Dickins11d31882005-09-03 15:54:34 -07001039 * extent list. The extent list is kept sorted in page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040 *
Hugh Dickins11d31882005-09-03 15:54:34 -07001041 * This function rather assumes that it is called in ascending page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042 */
1043static int
1044add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
1045 unsigned long nr_pages, sector_t start_block)
1046{
1047 struct swap_extent *se;
1048 struct swap_extent *new_se;
1049 struct list_head *lh;
1050
Hugh Dickins11d31882005-09-03 15:54:34 -07001051 lh = sis->extent_list.prev; /* The highest page extent */
1052 if (lh != &sis->extent_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001053 se = list_entry(lh, struct swap_extent, list);
Hugh Dickins11d31882005-09-03 15:54:34 -07001054 BUG_ON(se->start_page + se->nr_pages != start_page);
1055 if (se->start_block + se->nr_pages == start_block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 /* Merge it */
1057 se->nr_pages += nr_pages;
1058 return 0;
1059 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060 }
1061
1062 /*
1063 * No merge. Insert a new extent, preserving ordering.
1064 */
1065 new_se = kmalloc(sizeof(*se), GFP_KERNEL);
1066 if (new_se == NULL)
1067 return -ENOMEM;
1068 new_se->start_page = start_page;
1069 new_se->nr_pages = nr_pages;
1070 new_se->start_block = start_block;
1071
Hugh Dickins11d31882005-09-03 15:54:34 -07001072 list_add_tail(&new_se->list, &sis->extent_list);
Hugh Dickins53092a72005-09-03 15:54:34 -07001073 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001074}
1075
1076/*
1077 * A `swap extent' is a simple thing which maps a contiguous range of pages
1078 * onto a contiguous range of disk blocks. An ordered list of swap extents
1079 * is built at swapon time and is then used at swap_writepage/swap_readpage
1080 * time for locating where on disk a page belongs.
1081 *
1082 * If the swapfile is an S_ISBLK block device, a single extent is installed.
1083 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
1084 * swap files identically.
1085 *
1086 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
1087 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
1088 * swapfiles are handled *identically* after swapon time.
1089 *
1090 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
1091 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
1092 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
1093 * requirements, they are simply tossed out - we will never use those blocks
1094 * for swapping.
1095 *
Hugh Dickinsb0d9bcd2005-09-03 15:54:31 -07001096 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
1098 * which will scribble on the fs.
1099 *
1100 * The amount of disk space which a single swap extent represents varies.
1101 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
1102 * extents in the list. To avoid much list walking, we cache the previous
1103 * search location in `curr_swap_extent', and start new searches from there.
1104 * This is extremely effective. The average number of iterations in
1105 * map_swap_page() has been measured at about 0.3 per page. - akpm.
1106 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001107static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108{
1109 struct inode *inode;
1110 unsigned blocks_per_page;
1111 unsigned long page_no;
1112 unsigned blkbits;
1113 sector_t probe_block;
1114 sector_t last_block;
Hugh Dickins53092a72005-09-03 15:54:34 -07001115 sector_t lowest_block = -1;
1116 sector_t highest_block = 0;
1117 int nr_extents = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001118 int ret;
1119
1120 inode = sis->swap_file->f_mapping->host;
1121 if (S_ISBLK(inode->i_mode)) {
1122 ret = add_swap_extent(sis, 0, sis->max, 0);
Hugh Dickins53092a72005-09-03 15:54:34 -07001123 *span = sis->pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124 goto done;
1125 }
1126
1127 blkbits = inode->i_blkbits;
1128 blocks_per_page = PAGE_SIZE >> blkbits;
1129
1130 /*
1131 * Map all the blocks into the extent list. This code doesn't try
1132 * to be very smart.
1133 */
1134 probe_block = 0;
1135 page_no = 0;
1136 last_block = i_size_read(inode) >> blkbits;
1137 while ((probe_block + blocks_per_page) <= last_block &&
1138 page_no < sis->max) {
1139 unsigned block_in_page;
1140 sector_t first_block;
1141
1142 first_block = bmap(inode, probe_block);
1143 if (first_block == 0)
1144 goto bad_bmap;
1145
1146 /*
1147 * It must be PAGE_SIZE aligned on-disk
1148 */
1149 if (first_block & (blocks_per_page - 1)) {
1150 probe_block++;
1151 goto reprobe;
1152 }
1153
1154 for (block_in_page = 1; block_in_page < blocks_per_page;
1155 block_in_page++) {
1156 sector_t block;
1157
1158 block = bmap(inode, probe_block + block_in_page);
1159 if (block == 0)
1160 goto bad_bmap;
1161 if (block != first_block + block_in_page) {
1162 /* Discontiguity */
1163 probe_block++;
1164 goto reprobe;
1165 }
1166 }
1167
Hugh Dickins53092a72005-09-03 15:54:34 -07001168 first_block >>= (PAGE_SHIFT - blkbits);
1169 if (page_no) { /* exclude the header page */
1170 if (first_block < lowest_block)
1171 lowest_block = first_block;
1172 if (first_block > highest_block)
1173 highest_block = first_block;
1174 }
1175
Linus Torvalds1da177e2005-04-16 15:20:36 -07001176 /*
1177 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1178 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001179 ret = add_swap_extent(sis, page_no, 1, first_block);
1180 if (ret < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181 goto out;
Hugh Dickins53092a72005-09-03 15:54:34 -07001182 nr_extents += ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183 page_no++;
1184 probe_block += blocks_per_page;
1185reprobe:
1186 continue;
1187 }
Hugh Dickins53092a72005-09-03 15:54:34 -07001188 ret = nr_extents;
1189 *span = 1 + highest_block - lowest_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190 if (page_no == 0)
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001191 page_no = 1; /* force Empty message */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192 sis->max = page_no;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001193 sis->pages = page_no - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001194 sis->highest_bit = page_no - 1;
1195done:
1196 sis->curr_swap_extent = list_entry(sis->extent_list.prev,
1197 struct swap_extent, list);
1198 goto out;
1199bad_bmap:
1200 printk(KERN_ERR "swapon: swapfile has holes\n");
1201 ret = -EINVAL;
1202out:
1203 return ret;
1204}
1205
1206#if 0 /* We don't need this yet */
1207#include <linux/backing-dev.h>
1208int page_queue_congested(struct page *page)
1209{
1210 struct backing_dev_info *bdi;
1211
1212 BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */
1213
1214 if (PageSwapCache(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07001215 swp_entry_t entry = { .val = page_private(page) };
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 struct swap_info_struct *sis;
1217
1218 sis = get_swap_info_struct(swp_type(entry));
1219 bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info;
1220 } else
1221 bdi = page->mapping->backing_dev_info;
1222 return bdi_write_congested(bdi);
1223}
1224#endif
1225
1226asmlinkage long sys_swapoff(const char __user * specialfile)
1227{
1228 struct swap_info_struct * p = NULL;
1229 unsigned short *swap_map;
1230 struct file *swap_file, *victim;
1231 struct address_space *mapping;
1232 struct inode *inode;
1233 char * pathname;
1234 int i, type, prev;
1235 int err;
1236
1237 if (!capable(CAP_SYS_ADMIN))
1238 return -EPERM;
1239
1240 pathname = getname(specialfile);
1241 err = PTR_ERR(pathname);
1242 if (IS_ERR(pathname))
1243 goto out;
1244
1245 victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0);
1246 putname(pathname);
1247 err = PTR_ERR(victim);
1248 if (IS_ERR(victim))
1249 goto out;
1250
1251 mapping = victim->f_mapping;
1252 prev = -1;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001253 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254 for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
1255 p = swap_info + type;
1256 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
1257 if (p->swap_file->f_mapping == mapping)
1258 break;
1259 }
1260 prev = type;
1261 }
1262 if (type < 0) {
1263 err = -EINVAL;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001264 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001265 goto out_dput;
1266 }
1267 if (!security_vm_enough_memory(p->pages))
1268 vm_unacct_memory(p->pages);
1269 else {
1270 err = -ENOMEM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001271 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272 goto out_dput;
1273 }
1274 if (prev < 0) {
1275 swap_list.head = p->next;
1276 } else {
1277 swap_info[prev].next = p->next;
1278 }
1279 if (type == swap_list.next) {
1280 /* just pick something that's safe... */
1281 swap_list.next = swap_list.head;
1282 }
Hugh Dickins78ecba02008-07-23 21:28:23 -07001283 if (p->prio < 0) {
1284 for (i = p->next; i >= 0; i = swap_info[i].next)
1285 swap_info[i].prio = p->prio--;
1286 least_priority++;
1287 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001288 nr_swap_pages -= p->pages;
1289 total_swap_pages -= p->pages;
1290 p->flags &= ~SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001291 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -07001292
Linus Torvalds1da177e2005-04-16 15:20:36 -07001293 current->flags |= PF_SWAPOFF;
1294 err = try_to_unuse(type);
1295 current->flags &= ~PF_SWAPOFF;
1296
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297 if (err) {
1298 /* re-insert swap space back into swap_list */
Hugh Dickins5d337b92005-09-03 15:54:41 -07001299 spin_lock(&swap_lock);
Hugh Dickins78ecba02008-07-23 21:28:23 -07001300 if (p->prio < 0)
1301 p->prio = --least_priority;
1302 prev = -1;
1303 for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001304 if (p->prio >= swap_info[i].prio)
1305 break;
Hugh Dickins78ecba02008-07-23 21:28:23 -07001306 prev = i;
1307 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001308 p->next = i;
1309 if (prev < 0)
1310 swap_list.head = swap_list.next = p - swap_info;
1311 else
1312 swap_info[prev].next = p - swap_info;
1313 nr_swap_pages += p->pages;
1314 total_swap_pages += p->pages;
1315 p->flags |= SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001316 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001317 goto out_dput;
1318 }
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001319
1320 /* wait for any unplug function to finish */
1321 down_write(&swap_unplug_sem);
1322 up_write(&swap_unplug_sem);
1323
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001324 destroy_swap_extents(p);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001325 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001326 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327 drain_mmlist();
Hugh Dickins5d337b92005-09-03 15:54:41 -07001328
1329 /* wait for anyone still in scan_swap_map */
1330 p->highest_bit = 0; /* cuts scans short */
1331 while (p->flags >= SWP_SCANNING) {
1332 spin_unlock(&swap_lock);
Nishanth Aravamudan13e4b572005-09-10 00:27:25 -07001333 schedule_timeout_uninterruptible(1);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001334 spin_lock(&swap_lock);
1335 }
1336
Linus Torvalds1da177e2005-04-16 15:20:36 -07001337 swap_file = p->swap_file;
1338 p->swap_file = NULL;
1339 p->max = 0;
1340 swap_map = p->swap_map;
1341 p->swap_map = NULL;
1342 p->flags = 0;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001343 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001344 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345 vfree(swap_map);
1346 inode = mapping->host;
1347 if (S_ISBLK(inode->i_mode)) {
1348 struct block_device *bdev = I_BDEV(inode);
1349 set_blocksize(bdev, p->old_block_size);
1350 bd_release(bdev);
1351 } else {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001352 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353 inode->i_flags &= ~S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001354 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 }
1356 filp_close(swap_file, NULL);
1357 err = 0;
1358
1359out_dput:
1360 filp_close(victim, NULL);
1361out:
1362 return err;
1363}
1364
1365#ifdef CONFIG_PROC_FS
1366/* iterator */
1367static void *swap_start(struct seq_file *swap, loff_t *pos)
1368{
1369 struct swap_info_struct *ptr = swap_info;
1370 int i;
1371 loff_t l = *pos;
1372
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001373 mutex_lock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001375 if (!l)
1376 return SEQ_START_TOKEN;
1377
Linus Torvalds1da177e2005-04-16 15:20:36 -07001378 for (i = 0; i < nr_swapfiles; i++, ptr++) {
1379 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1380 continue;
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001381 if (!--l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 return ptr;
1383 }
1384
1385 return NULL;
1386}
1387
1388static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
1389{
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001390 struct swap_info_struct *ptr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391 struct swap_info_struct *endptr = swap_info + nr_swapfiles;
1392
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001393 if (v == SEQ_START_TOKEN)
1394 ptr = swap_info;
1395 else {
1396 ptr = v;
1397 ptr++;
1398 }
1399
1400 for (; ptr < endptr; ptr++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1402 continue;
1403 ++*pos;
1404 return ptr;
1405 }
1406
1407 return NULL;
1408}
1409
1410static void swap_stop(struct seq_file *swap, void *v)
1411{
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001412 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413}
1414
1415static int swap_show(struct seq_file *swap, void *v)
1416{
1417 struct swap_info_struct *ptr = v;
1418 struct file *file;
1419 int len;
1420
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001421 if (ptr == SEQ_START_TOKEN) {
1422 seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1423 return 0;
1424 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425
1426 file = ptr->swap_file;
Jan Blunckc32c2f62008-02-14 19:38:43 -08001427 len = seq_path(swap, &file->f_path, " \t\n\\");
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001428 seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429 len < 40 ? 40 - len : 1, " ",
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001430 S_ISBLK(file->f_path.dentry->d_inode->i_mode) ?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431 "partition" : "file\t",
1432 ptr->pages << (PAGE_SHIFT - 10),
1433 ptr->inuse_pages << (PAGE_SHIFT - 10),
1434 ptr->prio);
1435 return 0;
1436}
1437
Helge Deller15ad7cd2006-12-06 20:40:36 -08001438static const struct seq_operations swaps_op = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439 .start = swap_start,
1440 .next = swap_next,
1441 .stop = swap_stop,
1442 .show = swap_show
1443};
1444
1445static int swaps_open(struct inode *inode, struct file *file)
1446{
1447 return seq_open(file, &swaps_op);
1448}
1449
Helge Deller15ad7cd2006-12-06 20:40:36 -08001450static const struct file_operations proc_swaps_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001451 .open = swaps_open,
1452 .read = seq_read,
1453 .llseek = seq_lseek,
1454 .release = seq_release,
1455};
1456
1457static int __init procswaps_init(void)
1458{
Denis V. Lunev3d71f862008-04-29 01:02:13 -07001459 proc_create("swaps", 0, NULL, &proc_swaps_operations);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460 return 0;
1461}
1462__initcall(procswaps_init);
1463#endif /* CONFIG_PROC_FS */
1464
Jan Beulich17963162008-12-16 11:35:24 +00001465#ifdef MAX_SWAPFILES_CHECK
1466static int __init max_swapfiles_check(void)
1467{
1468 MAX_SWAPFILES_CHECK();
1469 return 0;
1470}
1471late_initcall(max_swapfiles_check);
1472#endif
1473
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474/*
1475 * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
1476 *
1477 * The swapon system call
1478 */
1479asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
1480{
1481 struct swap_info_struct * p;
1482 char *name = NULL;
1483 struct block_device *bdev = NULL;
1484 struct file *swap_file = NULL;
1485 struct address_space *mapping;
1486 unsigned int type;
1487 int i, prev;
1488 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489 union swap_header *swap_header = NULL;
1490 int swap_header_version;
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001491 unsigned int nr_good_pages = 0;
1492 int nr_extents = 0;
Hugh Dickins53092a72005-09-03 15:54:34 -07001493 sector_t span;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001494 unsigned long maxpages = 1;
1495 int swapfilesize;
Hugh Dickins78ecba02008-07-23 21:28:23 -07001496 unsigned short *swap_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001497 struct page *page = NULL;
1498 struct inode *inode = NULL;
1499 int did_down = 0;
1500
1501 if (!capable(CAP_SYS_ADMIN))
1502 return -EPERM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001503 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504 p = swap_info;
1505 for (type = 0 ; type < nr_swapfiles ; type++,p++)
1506 if (!(p->flags & SWP_USED))
1507 break;
1508 error = -EPERM;
Christoph Lameter06972122006-06-23 02:03:35 -07001509 if (type >= MAX_SWAPFILES) {
Hugh Dickins5d337b92005-09-03 15:54:41 -07001510 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511 goto out;
1512 }
1513 if (type >= nr_swapfiles)
1514 nr_swapfiles = type+1;
Hugh Dickins78ecba02008-07-23 21:28:23 -07001515 memset(p, 0, sizeof(*p));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516 INIT_LIST_HEAD(&p->extent_list);
1517 p->flags = SWP_USED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001518 p->next = -1;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001519 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001520 name = getname(specialfile);
1521 error = PTR_ERR(name);
1522 if (IS_ERR(name)) {
1523 name = NULL;
1524 goto bad_swap_2;
1525 }
1526 swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0);
1527 error = PTR_ERR(swap_file);
1528 if (IS_ERR(swap_file)) {
1529 swap_file = NULL;
1530 goto bad_swap_2;
1531 }
1532
1533 p->swap_file = swap_file;
1534 mapping = swap_file->f_mapping;
1535 inode = mapping->host;
1536
1537 error = -EBUSY;
1538 for (i = 0; i < nr_swapfiles; i++) {
1539 struct swap_info_struct *q = &swap_info[i];
1540
1541 if (i == type || !q->swap_file)
1542 continue;
1543 if (mapping == q->swap_file->f_mapping)
1544 goto bad_swap;
1545 }
1546
1547 error = -EINVAL;
1548 if (S_ISBLK(inode->i_mode)) {
1549 bdev = I_BDEV(inode);
1550 error = bd_claim(bdev, sys_swapon);
1551 if (error < 0) {
1552 bdev = NULL;
Rob Landleyf7b3a432005-09-22 21:44:27 -07001553 error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554 goto bad_swap;
1555 }
1556 p->old_block_size = block_size(bdev);
1557 error = set_blocksize(bdev, PAGE_SIZE);
1558 if (error < 0)
1559 goto bad_swap;
1560 p->bdev = bdev;
1561 } else if (S_ISREG(inode->i_mode)) {
1562 p->bdev = inode->i_sb->s_bdev;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001563 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564 did_down = 1;
1565 if (IS_SWAPFILE(inode)) {
1566 error = -EBUSY;
1567 goto bad_swap;
1568 }
1569 } else {
1570 goto bad_swap;
1571 }
1572
1573 swapfilesize = i_size_read(inode) >> PAGE_SHIFT;
1574
1575 /*
1576 * Read the swap header.
1577 */
1578 if (!mapping->a_ops->readpage) {
1579 error = -EINVAL;
1580 goto bad_swap;
1581 }
Pekka Enberg090d2b12006-06-23 02:05:08 -07001582 page = read_mapping_page(mapping, 0, swap_file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583 if (IS_ERR(page)) {
1584 error = PTR_ERR(page);
1585 goto bad_swap;
1586 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 kmap(page);
1588 swap_header = page_address(page);
1589
1590 if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
1591 swap_header_version = 1;
1592 else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
1593 swap_header_version = 2;
1594 else {
Jesper Juhle97a3112006-01-11 01:50:28 +01001595 printk(KERN_ERR "Unable to find swap-space signature\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596 error = -EINVAL;
1597 goto bad_swap;
1598 }
1599
1600 switch (swap_header_version) {
1601 case 1:
1602 printk(KERN_ERR "version 0 swap is no longer supported. "
1603 "Use mkswap -v1 %s\n", name);
1604 error = -EINVAL;
1605 goto bad_swap;
1606 case 2:
Chris Dearman797df572008-04-28 02:12:19 -07001607 /* swap partition endianess hack... */
1608 if (swab32(swap_header->info.version) == 1) {
1609 swab32s(&swap_header->info.version);
1610 swab32s(&swap_header->info.last_page);
1611 swab32s(&swap_header->info.nr_badpages);
1612 for (i = 0; i < swap_header->info.nr_badpages; i++)
1613 swab32s(&swap_header->info.badpages[i]);
1614 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001615 /* Check the swap header's sub-version and the size of
1616 the swap file and bad block lists */
1617 if (swap_header->info.version != 1) {
1618 printk(KERN_WARNING
1619 "Unable to handle swap header version %d\n",
1620 swap_header->info.version);
1621 error = -EINVAL;
1622 goto bad_swap;
1623 }
1624
1625 p->lowest_bit = 1;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001626 p->cluster_next = 1;
1627
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628 /*
1629 * Find out how many pages are allowed for a single swap
1630 * device. There are two limiting factors: 1) the number of
1631 * bits for the swap offset in the swp_entry_t type and
1632 * 2) the number of bits in the a swap pte as defined by
1633 * the different architectures. In order to find the
1634 * largest possible bit mask a swap entry with swap type 0
1635 * and swap offset ~0UL is created, encoded to a swap pte,
1636 * decoded to a swp_entry_t again and finally the swap
1637 * offset is extracted. This will mask all the bits from
1638 * the initial ~0UL mask that can't be encoded in either
1639 * the swp_entry_t or the architecture definition of a
1640 * swap pte.
1641 */
1642 maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1;
1643 if (maxpages > swap_header->info.last_page)
1644 maxpages = swap_header->info.last_page;
1645 p->highest_bit = maxpages - 1;
1646
1647 error = -EINVAL;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001648 if (!maxpages)
1649 goto bad_swap;
Eric Sandeen5d1854e2006-12-06 20:33:06 -08001650 if (swapfilesize && maxpages > swapfilesize) {
1651 printk(KERN_WARNING
1652 "Swap area shorter than signature indicates\n");
1653 goto bad_swap;
1654 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001655 if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
1656 goto bad_swap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001657 if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
1658 goto bad_swap;
Tobias Klausercd105df2006-01-08 01:00:59 -08001659
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 /* OK, set up the swap map and apply the bad block list */
Hugh Dickins78ecba02008-07-23 21:28:23 -07001661 swap_map = vmalloc(maxpages * sizeof(short));
1662 if (!swap_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001663 error = -ENOMEM;
1664 goto bad_swap;
1665 }
1666
1667 error = 0;
Hugh Dickins78ecba02008-07-23 21:28:23 -07001668 memset(swap_map, 0, maxpages * sizeof(short));
Tobias Klausercd105df2006-01-08 01:00:59 -08001669 for (i = 0; i < swap_header->info.nr_badpages; i++) {
1670 int page_nr = swap_header->info.badpages[i];
1671 if (page_nr <= 0 || page_nr >= swap_header->info.last_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001672 error = -EINVAL;
1673 else
Hugh Dickins78ecba02008-07-23 21:28:23 -07001674 swap_map[page_nr] = SWAP_MAP_BAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001675 }
1676 nr_good_pages = swap_header->info.last_page -
1677 swap_header->info.nr_badpages -
1678 1 /* header page */;
Tobias Klausercd105df2006-01-08 01:00:59 -08001679 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680 goto bad_swap;
1681 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001682
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001683 if (nr_good_pages) {
Hugh Dickins78ecba02008-07-23 21:28:23 -07001684 swap_map[0] = SWAP_MAP_BAD;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001685 p->max = maxpages;
1686 p->pages = nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001687 nr_extents = setup_swap_extents(p, &span);
1688 if (nr_extents < 0) {
1689 error = nr_extents;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001690 goto bad_swap;
Hugh Dickins53092a72005-09-03 15:54:34 -07001691 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001692 nr_good_pages = p->pages;
1693 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001694 if (!nr_good_pages) {
1695 printk(KERN_WARNING "Empty swap-file\n");
1696 error = -EINVAL;
1697 goto bad_swap;
1698 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001700 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001701 spin_lock(&swap_lock);
Hugh Dickins78ecba02008-07-23 21:28:23 -07001702 if (swap_flags & SWAP_FLAG_PREFER)
1703 p->prio =
1704 (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT;
1705 else
1706 p->prio = --least_priority;
1707 p->swap_map = swap_map;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001708 p->flags = SWP_ACTIVE;
1709 nr_swap_pages += nr_good_pages;
1710 total_swap_pages += nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001711
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001712 printk(KERN_INFO "Adding %uk swap on %s. "
Hugh Dickins53092a72005-09-03 15:54:34 -07001713 "Priority:%d extents:%d across:%lluk\n",
1714 nr_good_pages<<(PAGE_SHIFT-10), name, p->prio,
1715 nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716
1717 /* insert swap space into swap_list: */
1718 prev = -1;
1719 for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
1720 if (p->prio >= swap_info[i].prio) {
1721 break;
1722 }
1723 prev = i;
1724 }
1725 p->next = i;
1726 if (prev < 0) {
1727 swap_list.head = swap_list.next = p - swap_info;
1728 } else {
1729 swap_info[prev].next = p - swap_info;
1730 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001731 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001732 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001733 error = 0;
1734 goto out;
1735bad_swap:
1736 if (bdev) {
1737 set_blocksize(bdev, p->old_block_size);
1738 bd_release(bdev);
1739 }
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001740 destroy_swap_extents(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741bad_swap_2:
Hugh Dickins5d337b92005-09-03 15:54:41 -07001742 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001743 p->swap_file = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 p->flags = 0;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001745 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001746 vfree(swap_map);
1747 if (swap_file)
1748 filp_close(swap_file, NULL);
1749out:
1750 if (page && !IS_ERR(page)) {
1751 kunmap(page);
1752 page_cache_release(page);
1753 }
1754 if (name)
1755 putname(name);
1756 if (did_down) {
1757 if (!error)
1758 inode->i_flags |= S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001759 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760 }
1761 return error;
1762}
1763
1764void si_swapinfo(struct sysinfo *val)
1765{
1766 unsigned int i;
1767 unsigned long nr_to_be_unused = 0;
1768
Hugh Dickins5d337b92005-09-03 15:54:41 -07001769 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001770 for (i = 0; i < nr_swapfiles; i++) {
1771 if (!(swap_info[i].flags & SWP_USED) ||
1772 (swap_info[i].flags & SWP_WRITEOK))
1773 continue;
1774 nr_to_be_unused += swap_info[i].inuse_pages;
1775 }
1776 val->freeswap = nr_swap_pages + nr_to_be_unused;
1777 val->totalswap = total_swap_pages + nr_to_be_unused;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001778 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001779}
1780
1781/*
1782 * Verify that a swap entry is valid and increment its swap map count.
1783 *
1784 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
1785 * "permanent", but will be reclaimed by the next swapoff.
1786 */
1787int swap_duplicate(swp_entry_t entry)
1788{
1789 struct swap_info_struct * p;
1790 unsigned long offset, type;
1791 int result = 0;
1792
Christoph Lameter06972122006-06-23 02:03:35 -07001793 if (is_migration_entry(entry))
1794 return 1;
1795
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796 type = swp_type(entry);
1797 if (type >= nr_swapfiles)
1798 goto bad_file;
1799 p = type + swap_info;
1800 offset = swp_offset(entry);
1801
Hugh Dickins5d337b92005-09-03 15:54:41 -07001802 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001803 if (offset < p->max && p->swap_map[offset]) {
1804 if (p->swap_map[offset] < SWAP_MAP_MAX - 1) {
1805 p->swap_map[offset]++;
1806 result = 1;
1807 } else if (p->swap_map[offset] <= SWAP_MAP_MAX) {
1808 if (swap_overflow++ < 5)
1809 printk(KERN_WARNING "swap_dup: swap entry overflow\n");
1810 p->swap_map[offset] = SWAP_MAP_MAX;
1811 result = 1;
1812 }
1813 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001814 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815out:
1816 return result;
1817
1818bad_file:
1819 printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
1820 goto out;
1821}
1822
1823struct swap_info_struct *
1824get_swap_info_struct(unsigned type)
1825{
1826 return &swap_info[type];
1827}
1828
1829/*
Hugh Dickins5d337b92005-09-03 15:54:41 -07001830 * swap_lock prevents swap_map being freed. Don't grab an extra
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831 * reference on the swaphandle, it doesn't matter if it becomes unused.
1832 */
1833int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
1834{
Hugh Dickins89528982008-02-04 22:28:45 -08001835 struct swap_info_struct *si;
Hugh Dickins3f9e7942006-09-29 02:01:26 -07001836 int our_page_cluster = page_cluster;
Hugh Dickins89528982008-02-04 22:28:45 -08001837 pgoff_t target, toff;
1838 pgoff_t base, end;
1839 int nr_pages = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001840
Hugh Dickins3f9e7942006-09-29 02:01:26 -07001841 if (!our_page_cluster) /* no readahead */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001842 return 0;
Hugh Dickins89528982008-02-04 22:28:45 -08001843
1844 si = &swap_info[swp_type(entry)];
1845 target = swp_offset(entry);
1846 base = (target >> our_page_cluster) << our_page_cluster;
1847 end = base + (1 << our_page_cluster);
1848 if (!base) /* first page is swap header */
1849 base++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001850
Hugh Dickins5d337b92005-09-03 15:54:41 -07001851 spin_lock(&swap_lock);
Hugh Dickins89528982008-02-04 22:28:45 -08001852 if (end > si->max) /* don't go beyond end of map */
1853 end = si->max;
1854
1855 /* Count contiguous allocated slots above our target */
1856 for (toff = target; ++toff < end; nr_pages++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001857 /* Don't read in free or bad pages */
Hugh Dickins89528982008-02-04 22:28:45 -08001858 if (!si->swap_map[toff])
Linus Torvalds1da177e2005-04-16 15:20:36 -07001859 break;
Hugh Dickins89528982008-02-04 22:28:45 -08001860 if (si->swap_map[toff] == SWAP_MAP_BAD)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001861 break;
Hugh Dickins89528982008-02-04 22:28:45 -08001862 }
1863 /* Count contiguous allocated slots below our target */
1864 for (toff = target; --toff >= base; nr_pages++) {
1865 /* Don't read in free or bad pages */
1866 if (!si->swap_map[toff])
1867 break;
1868 if (si->swap_map[toff] == SWAP_MAP_BAD)
1869 break;
1870 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001871 spin_unlock(&swap_lock);
Hugh Dickins89528982008-02-04 22:28:45 -08001872
1873 /*
1874 * Indicate starting offset, and return number of pages to get:
1875 * if only 1, say 0, since there's then no readahead to be done.
1876 */
1877 *offset = ++toff;
1878 return nr_pages? ++nr_pages: 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001879}