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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>
30
31#include <asm/pgtable.h>
32#include <asm/tlbflush.h>
33#include <linux/swapops.h>
34
Hugh Dickins5d337b92005-09-03 15:54:41 -070035DEFINE_SPINLOCK(swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070036unsigned int nr_swapfiles;
37long total_swap_pages;
38static int swap_overflow;
39
Linus Torvalds1da177e2005-04-16 15:20:36 -070040static const char Bad_file[] = "Bad swap file entry ";
41static const char Unused_file[] = "Unused swap file entry ";
42static const char Bad_offset[] = "Bad swap offset entry ";
43static const char Unused_offset[] = "Unused swap offset entry ";
44
45struct swap_list_t swap_list = {-1, -1};
46
Rafael J. Wysockif577eb32006-03-23 02:59:59 -080047static struct swap_info_struct swap_info[MAX_SWAPFILES];
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
Ingo Molnarfc0abb12006-01-18 17:42:33 -080049static DEFINE_MUTEX(swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
51/*
52 * We need this because the bdev->unplug_fn can sleep and we cannot
Hugh Dickins5d337b92005-09-03 15:54:41 -070053 * hold swap_lock while calling the unplug_fn. And swap_lock
Ingo Molnarfc0abb12006-01-18 17:42:33 -080054 * cannot be turned into a mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 */
56static DECLARE_RWSEM(swap_unplug_sem);
57
Linus Torvalds1da177e2005-04-16 15:20:36 -070058void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page)
59{
60 swp_entry_t entry;
61
62 down_read(&swap_unplug_sem);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070063 entry.val = page_private(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 if (PageSwapCache(page)) {
65 struct block_device *bdev = swap_info[swp_type(entry)].bdev;
66 struct backing_dev_info *bdi;
67
68 /*
69 * If the page is removed from swapcache from under us (with a
70 * racy try_to_unuse/swapoff) we need an additional reference
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070071 * count to avoid reading garbage from page_private(page) above.
72 * If the WARN_ON triggers during a swapoff it maybe the race
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 * condition and it's harmless. However if it triggers without
74 * swapoff it signals a problem.
75 */
76 WARN_ON(page_count(page) <= 1);
77
78 bdi = bdev->bd_inode->i_mapping->backing_dev_info;
McMullan, Jasonba323112005-05-16 21:53:40 -070079 blk_run_backing_dev(bdi, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 }
81 up_read(&swap_unplug_sem);
82}
83
Hugh Dickins048c27f2005-09-03 15:54:40 -070084#define SWAPFILE_CLUSTER 256
85#define LATENCY_LIMIT 256
86
Hugh Dickins6eb396d2005-09-03 15:54:35 -070087static inline unsigned long scan_swap_map(struct swap_info_struct *si)
Linus Torvalds1da177e2005-04-16 15:20:36 -070088{
Hugh Dickins7dfad412005-09-03 15:54:38 -070089 unsigned long offset, last_in_cluster;
Hugh Dickins048c27f2005-09-03 15:54:40 -070090 int latency_ration = LATENCY_LIMIT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070091
Hugh Dickins7dfad412005-09-03 15:54:38 -070092 /*
93 * We try to cluster swap pages by allocating them sequentially
94 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this
95 * way, however, we resort to first-free allocation, starting
96 * a new cluster. This prevents us from scattering swap pages
97 * all over the entire swap partition, so that we reduce
98 * overall disk seek times between swap pages. -- sct
99 * But we do now try to find an empty cluster. -Andrea
100 */
101
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700102 si->flags += SWP_SCANNING;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700103 if (unlikely(!si->cluster_nr)) {
104 si->cluster_nr = SWAPFILE_CLUSTER - 1;
105 if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER)
106 goto lowest;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700107 spin_unlock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700108
109 offset = si->lowest_bit;
110 last_in_cluster = offset + SWAPFILE_CLUSTER - 1;
111
112 /* Locate the first empty (unaligned) cluster */
113 for (; last_in_cluster <= si->highest_bit; offset++) {
114 if (si->swap_map[offset])
115 last_in_cluster = offset + SWAPFILE_CLUSTER;
116 else if (offset == last_in_cluster) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700117 spin_lock(&swap_lock);
Akinobu Mita9b65ef52006-03-22 00:09:09 -0800118 si->cluster_next = offset-SWAPFILE_CLUSTER+1;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700119 goto cluster;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 }
Hugh Dickins048c27f2005-09-03 15:54:40 -0700121 if (unlikely(--latency_ration < 0)) {
122 cond_resched();
123 latency_ration = LATENCY_LIMIT;
124 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700125 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700126 spin_lock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700127 goto lowest;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700129
130 si->cluster_nr--;
131cluster:
132 offset = si->cluster_next;
133 if (offset > si->highest_bit)
134lowest: offset = si->lowest_bit;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700135checks: if (!(si->flags & SWP_WRITEOK))
136 goto no_page;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700137 if (!si->highest_bit)
138 goto no_page;
139 if (!si->swap_map[offset]) {
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700140 if (offset == si->lowest_bit)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 si->lowest_bit++;
142 if (offset == si->highest_bit)
143 si->highest_bit--;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700144 si->inuse_pages++;
145 if (si->inuse_pages == si->pages) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 si->lowest_bit = si->max;
147 si->highest_bit = 0;
148 }
149 si->swap_map[offset] = 1;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700150 si->cluster_next = offset + 1;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700151 si->flags -= SWP_SCANNING;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 return offset;
153 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700154
Hugh Dickins5d337b92005-09-03 15:54:41 -0700155 spin_unlock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700156 while (++offset <= si->highest_bit) {
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700157 if (!si->swap_map[offset]) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700158 spin_lock(&swap_lock);
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700159 goto checks;
160 }
Hugh Dickins048c27f2005-09-03 15:54:40 -0700161 if (unlikely(--latency_ration < 0)) {
162 cond_resched();
163 latency_ration = LATENCY_LIMIT;
164 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700165 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700166 spin_lock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700167 goto lowest;
168
169no_page:
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700170 si->flags -= SWP_SCANNING;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 return 0;
172}
173
174swp_entry_t get_swap_page(void)
175{
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700176 struct swap_info_struct *si;
177 pgoff_t offset;
178 int type, next;
179 int wrapped = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180
Hugh Dickins5d337b92005-09-03 15:54:41 -0700181 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 if (nr_swap_pages <= 0)
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700183 goto noswap;
184 nr_swap_pages--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700186 for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) {
187 si = swap_info + type;
188 next = si->next;
189 if (next < 0 ||
190 (!wrapped && si->prio != swap_info[next].prio)) {
191 next = swap_list.head;
192 wrapped++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 }
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700194
195 if (!si->highest_bit)
196 continue;
197 if (!(si->flags & SWP_WRITEOK))
198 continue;
199
200 swap_list.next = next;
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700201 offset = scan_swap_map(si);
Hugh Dickins5d337b92005-09-03 15:54:41 -0700202 if (offset) {
203 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700204 return swp_entry(type, offset);
Hugh Dickins5d337b92005-09-03 15:54:41 -0700205 }
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700206 next = swap_list.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 }
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700208
209 nr_swap_pages++;
210noswap:
Hugh Dickins5d337b92005-09-03 15:54:41 -0700211 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700212 return (swp_entry_t) {0};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213}
214
Rafael J. Wysocki3a291a22006-01-06 00:16:37 -0800215swp_entry_t get_swap_page_of_type(int type)
216{
217 struct swap_info_struct *si;
218 pgoff_t offset;
219
220 spin_lock(&swap_lock);
221 si = swap_info + type;
222 if (si->flags & SWP_WRITEOK) {
223 nr_swap_pages--;
224 offset = scan_swap_map(si);
225 if (offset) {
226 spin_unlock(&swap_lock);
227 return swp_entry(type, offset);
228 }
229 nr_swap_pages++;
230 }
231 spin_unlock(&swap_lock);
232 return (swp_entry_t) {0};
233}
234
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235static struct swap_info_struct * swap_info_get(swp_entry_t entry)
236{
237 struct swap_info_struct * p;
238 unsigned long offset, type;
239
240 if (!entry.val)
241 goto out;
242 type = swp_type(entry);
243 if (type >= nr_swapfiles)
244 goto bad_nofile;
245 p = & swap_info[type];
246 if (!(p->flags & SWP_USED))
247 goto bad_device;
248 offset = swp_offset(entry);
249 if (offset >= p->max)
250 goto bad_offset;
251 if (!p->swap_map[offset])
252 goto bad_free;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700253 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 return p;
255
256bad_free:
257 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val);
258 goto out;
259bad_offset:
260 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val);
261 goto out;
262bad_device:
263 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val);
264 goto out;
265bad_nofile:
266 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val);
267out:
268 return NULL;
269}
270
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271static int swap_entry_free(struct swap_info_struct *p, unsigned long offset)
272{
273 int count = p->swap_map[offset];
274
275 if (count < SWAP_MAP_MAX) {
276 count--;
277 p->swap_map[offset] = count;
278 if (!count) {
279 if (offset < p->lowest_bit)
280 p->lowest_bit = offset;
281 if (offset > p->highest_bit)
282 p->highest_bit = offset;
Hugh Dickins89d09a22005-09-03 15:54:36 -0700283 if (p->prio > swap_info[swap_list.next].prio)
284 swap_list.next = p - swap_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 nr_swap_pages++;
286 p->inuse_pages--;
287 }
288 }
289 return count;
290}
291
292/*
293 * Caller has made sure that the swapdevice corresponding to entry
294 * is still around or has not been recycled.
295 */
296void swap_free(swp_entry_t entry)
297{
298 struct swap_info_struct * p;
299
300 p = swap_info_get(entry);
301 if (p) {
302 swap_entry_free(p, swp_offset(entry));
Hugh Dickins5d337b92005-09-03 15:54:41 -0700303 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 }
305}
306
307/*
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700308 * How many references to page are currently swapped out?
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309 */
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700310static inline int page_swapcount(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311{
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700312 int count = 0;
313 struct swap_info_struct *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 swp_entry_t entry;
315
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700316 entry.val = page_private(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 p = swap_info_get(entry);
318 if (p) {
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700319 /* Subtract the 1 for the swap cache itself */
320 count = p->swap_map[swp_offset(entry)] - 1;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700321 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 }
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700323 return count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324}
325
326/*
327 * We can use this swap cache entry directly
328 * if there are no other references to it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 */
330int can_share_swap_page(struct page *page)
331{
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700332 int count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700334 BUG_ON(!PageLocked(page));
335 count = page_mapcount(page);
336 if (count <= 1 && PageSwapCache(page))
337 count += page_swapcount(page);
338 return count == 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339}
340
341/*
342 * Work out if there are any other processes sharing this
343 * swap cache page. Free it if you can. Return success.
344 */
345int remove_exclusive_swap_page(struct page *page)
346{
347 int retval;
348 struct swap_info_struct * p;
349 swp_entry_t entry;
350
351 BUG_ON(PagePrivate(page));
352 BUG_ON(!PageLocked(page));
353
354 if (!PageSwapCache(page))
355 return 0;
356 if (PageWriteback(page))
357 return 0;
358 if (page_count(page) != 2) /* 2: us + cache */
359 return 0;
360
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700361 entry.val = page_private(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 p = swap_info_get(entry);
363 if (!p)
364 return 0;
365
366 /* Is the only swap cache user the cache itself? */
367 retval = 0;
368 if (p->swap_map[swp_offset(entry)] == 1) {
369 /* Recheck the page count with the swapcache lock held.. */
370 write_lock_irq(&swapper_space.tree_lock);
371 if ((page_count(page) == 2) && !PageWriteback(page)) {
372 __delete_from_swap_cache(page);
373 SetPageDirty(page);
374 retval = 1;
375 }
376 write_unlock_irq(&swapper_space.tree_lock);
377 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700378 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379
380 if (retval) {
381 swap_free(entry);
382 page_cache_release(page);
383 }
384
385 return retval;
386}
387
388/*
389 * Free the swap entry like above, but also try to
390 * free the page cache entry if it is the last user.
391 */
392void free_swap_and_cache(swp_entry_t entry)
393{
394 struct swap_info_struct * p;
395 struct page *page = NULL;
396
Christoph Lameter06972122006-06-23 02:03:35 -0700397 if (is_migration_entry(entry))
398 return;
399
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 p = swap_info_get(entry);
401 if (p) {
Nick Piggin93fac702006-03-31 02:29:56 -0800402 if (swap_entry_free(p, swp_offset(entry)) == 1) {
403 page = find_get_page(&swapper_space, entry.val);
404 if (page && unlikely(TestSetPageLocked(page))) {
405 page_cache_release(page);
406 page = NULL;
407 }
408 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700409 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 }
411 if (page) {
412 int one_user;
413
414 BUG_ON(PagePrivate(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 one_user = (page_count(page) == 2);
416 /* Only cache user (+us), or swap space full? Free it! */
Nick Piggin93fac702006-03-31 02:29:56 -0800417 /* Also recheck PageSwapCache after page is locked (above) */
418 if (PageSwapCache(page) && !PageWriteback(page) &&
419 (one_user || vm_swap_full())) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 delete_from_swap_cache(page);
421 SetPageDirty(page);
422 }
423 unlock_page(page);
424 page_cache_release(page);
425 }
426}
427
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800428#ifdef CONFIG_SOFTWARE_SUSPEND
429/*
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800430 * Find the swap type that corresponds to given device (if any).
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800431 *
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800432 * @offset - number of the PAGE_SIZE-sized block of the device, starting
433 * from 0, in which the swap header is expected to be located.
434 *
435 * This is needed for the suspend to disk (aka swsusp).
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800436 */
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800437int swap_type_of(dev_t device, sector_t offset)
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800438{
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800439 struct block_device *bdev = NULL;
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800440 int i;
441
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800442 if (device)
443 bdev = bdget(device);
444
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800445 spin_lock(&swap_lock);
446 for (i = 0; i < nr_swapfiles; i++) {
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800447 struct swap_info_struct *sis = swap_info + i;
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800448
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800449 if (!(sis->flags & SWP_WRITEOK))
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800450 continue;
Rafael J. Wysockib6b5bce2006-08-27 01:23:25 -0700451
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800452 if (!bdev) {
Rafael J. Wysocki6e1819d2006-03-23 03:00:03 -0800453 spin_unlock(&swap_lock);
454 return i;
455 }
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800456 if (bdev == sis->bdev) {
457 struct swap_extent *se;
458
459 se = list_entry(sis->extent_list.next,
460 struct swap_extent, list);
461 if (se->start_block == offset) {
462 spin_unlock(&swap_lock);
463 bdput(bdev);
464 return i;
465 }
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800466 }
467 }
468 spin_unlock(&swap_lock);
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800469 if (bdev)
470 bdput(bdev);
471
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800472 return -ENODEV;
473}
474
475/*
476 * Return either the total number of swap pages of given type, or the number
477 * of free pages of that type (depending on @free)
478 *
479 * This is needed for software suspend
480 */
481unsigned int count_swap_pages(int type, int free)
482{
483 unsigned int n = 0;
484
485 if (type < nr_swapfiles) {
486 spin_lock(&swap_lock);
487 if (swap_info[type].flags & SWP_WRITEOK) {
488 n = swap_info[type].pages;
489 if (free)
490 n -= swap_info[type].inuse_pages;
491 }
492 spin_unlock(&swap_lock);
493 }
494 return n;
495}
496#endif
497
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498/*
Hugh Dickins72866f62005-10-29 18:15:55 -0700499 * No need to decide whether this PTE shares the swap entry with others,
500 * just let do_wp_page work it out if a write is requested later - to
501 * force COW, vm_page_prot omits write permission from any private vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502 */
503static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
504 unsigned long addr, swp_entry_t entry, struct page *page)
505{
Hugh Dickins42946212005-10-29 18:16:05 -0700506 inc_mm_counter(vma->vm_mm, anon_rss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 get_page(page);
508 set_pte_at(vma->vm_mm, addr, pte,
509 pte_mkold(mk_pte(page, vma->vm_page_prot)));
510 page_add_anon_rmap(page, vma, addr);
511 swap_free(entry);
512 /*
513 * Move the page to the active list so it is not
514 * immediately swapped out again after swapon.
515 */
516 activate_page(page);
517}
518
519static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
520 unsigned long addr, unsigned long end,
521 swp_entry_t entry, struct page *page)
522{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523 pte_t swp_pte = swp_entry_to_pte(entry);
Hugh Dickins705e87c2005-10-29 18:16:27 -0700524 pte_t *pte;
525 spinlock_t *ptl;
526 int found = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527
Hugh Dickins705e87c2005-10-29 18:16:27 -0700528 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 do {
530 /*
531 * swapoff spends a _lot_ of time in this loop!
532 * Test inline before going to call unuse_pte.
533 */
534 if (unlikely(pte_same(*pte, swp_pte))) {
Hugh Dickins705e87c2005-10-29 18:16:27 -0700535 unuse_pte(vma, pte++, addr, entry, page);
536 found = 1;
537 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 }
539 } while (pte++, addr += PAGE_SIZE, addr != end);
Hugh Dickins705e87c2005-10-29 18:16:27 -0700540 pte_unmap_unlock(pte - 1, ptl);
541 return found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542}
543
544static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
545 unsigned long addr, unsigned long end,
546 swp_entry_t entry, struct page *page)
547{
548 pmd_t *pmd;
549 unsigned long next;
550
551 pmd = pmd_offset(pud, addr);
552 do {
553 next = pmd_addr_end(addr, end);
554 if (pmd_none_or_clear_bad(pmd))
555 continue;
556 if (unuse_pte_range(vma, pmd, addr, next, entry, page))
557 return 1;
558 } while (pmd++, addr = next, addr != end);
559 return 0;
560}
561
562static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
563 unsigned long addr, unsigned long end,
564 swp_entry_t entry, struct page *page)
565{
566 pud_t *pud;
567 unsigned long next;
568
569 pud = pud_offset(pgd, addr);
570 do {
571 next = pud_addr_end(addr, end);
572 if (pud_none_or_clear_bad(pud))
573 continue;
574 if (unuse_pmd_range(vma, pud, addr, next, entry, page))
575 return 1;
576 } while (pud++, addr = next, addr != end);
577 return 0;
578}
579
580static int unuse_vma(struct vm_area_struct *vma,
581 swp_entry_t entry, struct page *page)
582{
583 pgd_t *pgd;
584 unsigned long addr, end, next;
585
586 if (page->mapping) {
587 addr = page_address_in_vma(page, vma);
588 if (addr == -EFAULT)
589 return 0;
590 else
591 end = addr + PAGE_SIZE;
592 } else {
593 addr = vma->vm_start;
594 end = vma->vm_end;
595 }
596
597 pgd = pgd_offset(vma->vm_mm, addr);
598 do {
599 next = pgd_addr_end(addr, end);
600 if (pgd_none_or_clear_bad(pgd))
601 continue;
602 if (unuse_pud_range(vma, pgd, addr, next, entry, page))
603 return 1;
604 } while (pgd++, addr = next, addr != end);
605 return 0;
606}
607
608static int unuse_mm(struct mm_struct *mm,
609 swp_entry_t entry, struct page *page)
610{
611 struct vm_area_struct *vma;
612
613 if (!down_read_trylock(&mm->mmap_sem)) {
614 /*
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700615 * Activate page so shrink_cache is unlikely to unmap its
616 * ptes while lock is dropped, so swapoff can make progress.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 */
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700618 activate_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619 unlock_page(page);
620 down_read(&mm->mmap_sem);
621 lock_page(page);
622 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623 for (vma = mm->mmap; vma; vma = vma->vm_next) {
624 if (vma->anon_vma && unuse_vma(vma, entry, page))
625 break;
626 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 up_read(&mm->mmap_sem);
628 /*
629 * Currently unuse_mm cannot fail, but leave error handling
630 * at call sites for now, since we change it from time to time.
631 */
632 return 0;
633}
634
635/*
636 * Scan swap_map from current position to next entry still in use.
637 * Recycle to start on reaching the end, returning 0 when empty.
638 */
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700639static unsigned int find_next_to_unuse(struct swap_info_struct *si,
640 unsigned int prev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641{
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700642 unsigned int max = si->max;
643 unsigned int i = prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644 int count;
645
646 /*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700647 * No need for swap_lock here: we're just looking
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 * for whether an entry is in use, not modifying it; false
649 * hits are okay, and sys_swapoff() has already prevented new
Hugh Dickins5d337b92005-09-03 15:54:41 -0700650 * allocations from this area (while holding swap_lock).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 */
652 for (;;) {
653 if (++i >= max) {
654 if (!prev) {
655 i = 0;
656 break;
657 }
658 /*
659 * No entries in use at top of swap_map,
660 * loop back to start and recheck there.
661 */
662 max = prev + 1;
663 prev = 0;
664 i = 1;
665 }
666 count = si->swap_map[i];
667 if (count && count != SWAP_MAP_BAD)
668 break;
669 }
670 return i;
671}
672
673/*
674 * We completely avoid races by reading each swap page in advance,
675 * and then search for the process using it. All the necessary
676 * page table adjustments can then be made atomically.
677 */
678static int try_to_unuse(unsigned int type)
679{
680 struct swap_info_struct * si = &swap_info[type];
681 struct mm_struct *start_mm;
682 unsigned short *swap_map;
683 unsigned short swcount;
684 struct page *page;
685 swp_entry_t entry;
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700686 unsigned int i = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 int retval = 0;
688 int reset_overflow = 0;
689 int shmem;
690
691 /*
692 * When searching mms for an entry, a good strategy is to
693 * start at the first mm we freed the previous entry from
694 * (though actually we don't notice whether we or coincidence
695 * freed the entry). Initialize this start_mm with a hold.
696 *
697 * A simpler strategy would be to start at the last mm we
698 * freed the previous entry from; but that would take less
699 * advantage of mmlist ordering, which clusters forked mms
700 * together, child after parent. If we race with dup_mmap(), we
701 * prefer to resolve parent before child, lest we miss entries
702 * duplicated after we scanned child: using last mm would invert
703 * that. Though it's only a serious concern when an overflowed
704 * swap count is reset from SWAP_MAP_MAX, preventing a rescan.
705 */
706 start_mm = &init_mm;
707 atomic_inc(&init_mm.mm_users);
708
709 /*
710 * Keep on scanning until all entries have gone. Usually,
711 * one pass through swap_map is enough, but not necessarily:
712 * there are races when an instance of an entry might be missed.
713 */
714 while ((i = find_next_to_unuse(si, i)) != 0) {
715 if (signal_pending(current)) {
716 retval = -EINTR;
717 break;
718 }
719
720 /*
721 * Get a page for the entry, using the existing swap
722 * cache page if there is one. Otherwise, get a clean
723 * page and read the swap into it.
724 */
725 swap_map = &si->swap_map[i];
726 entry = swp_entry(type, i);
727 page = read_swap_cache_async(entry, NULL, 0);
728 if (!page) {
729 /*
730 * Either swap_duplicate() failed because entry
731 * has been freed independently, and will not be
732 * reused since sys_swapoff() already disabled
733 * allocation from here, or alloc_page() failed.
734 */
735 if (!*swap_map)
736 continue;
737 retval = -ENOMEM;
738 break;
739 }
740
741 /*
742 * Don't hold on to start_mm if it looks like exiting.
743 */
744 if (atomic_read(&start_mm->mm_users) == 1) {
745 mmput(start_mm);
746 start_mm = &init_mm;
747 atomic_inc(&init_mm.mm_users);
748 }
749
750 /*
751 * Wait for and lock page. When do_swap_page races with
752 * try_to_unuse, do_swap_page can handle the fault much
753 * faster than try_to_unuse can locate the entry. This
754 * apparently redundant "wait_on_page_locked" lets try_to_unuse
755 * defer to do_swap_page in such a case - in some tests,
756 * do_swap_page and try_to_unuse repeatedly compete.
757 */
758 wait_on_page_locked(page);
759 wait_on_page_writeback(page);
760 lock_page(page);
761 wait_on_page_writeback(page);
762
763 /*
764 * Remove all references to entry.
765 * Whenever we reach init_mm, there's no address space
766 * to search, but use it as a reminder to search shmem.
767 */
768 shmem = 0;
769 swcount = *swap_map;
770 if (swcount > 1) {
771 if (start_mm == &init_mm)
772 shmem = shmem_unuse(entry, page);
773 else
774 retval = unuse_mm(start_mm, entry, page);
775 }
776 if (*swap_map > 1) {
777 int set_start_mm = (*swap_map >= swcount);
778 struct list_head *p = &start_mm->mmlist;
779 struct mm_struct *new_start_mm = start_mm;
780 struct mm_struct *prev_mm = start_mm;
781 struct mm_struct *mm;
782
783 atomic_inc(&new_start_mm->mm_users);
784 atomic_inc(&prev_mm->mm_users);
785 spin_lock(&mmlist_lock);
786 while (*swap_map > 1 && !retval &&
787 (p = p->next) != &start_mm->mmlist) {
788 mm = list_entry(p, struct mm_struct, mmlist);
Hugh Dickins70af7c52006-06-23 02:03:44 -0700789 if (!atomic_inc_not_zero(&mm->mm_users))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791 spin_unlock(&mmlist_lock);
792 mmput(prev_mm);
793 prev_mm = mm;
794
795 cond_resched();
796
797 swcount = *swap_map;
798 if (swcount <= 1)
799 ;
800 else if (mm == &init_mm) {
801 set_start_mm = 1;
802 shmem = shmem_unuse(entry, page);
803 } else
804 retval = unuse_mm(mm, entry, page);
805 if (set_start_mm && *swap_map < swcount) {
806 mmput(new_start_mm);
807 atomic_inc(&mm->mm_users);
808 new_start_mm = mm;
809 set_start_mm = 0;
810 }
811 spin_lock(&mmlist_lock);
812 }
813 spin_unlock(&mmlist_lock);
814 mmput(prev_mm);
815 mmput(start_mm);
816 start_mm = new_start_mm;
817 }
818 if (retval) {
819 unlock_page(page);
820 page_cache_release(page);
821 break;
822 }
823
824 /*
825 * How could swap count reach 0x7fff when the maximum
826 * pid is 0x7fff, and there's no way to repeat a swap
827 * page within an mm (except in shmem, where it's the
828 * shared object which takes the reference count)?
829 * We believe SWAP_MAP_MAX cannot occur in Linux 2.4.
830 *
831 * If that's wrong, then we should worry more about
832 * exit_mmap() and do_munmap() cases described above:
833 * we might be resetting SWAP_MAP_MAX too early here.
834 * We know "Undead"s can happen, they're okay, so don't
835 * report them; but do report if we reset SWAP_MAP_MAX.
836 */
837 if (*swap_map == SWAP_MAP_MAX) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700838 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839 *swap_map = 1;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700840 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841 reset_overflow = 1;
842 }
843
844 /*
845 * If a reference remains (rare), we would like to leave
846 * the page in the swap cache; but try_to_unmap could
847 * then re-duplicate the entry once we drop page lock,
848 * so we might loop indefinitely; also, that page could
849 * not be swapped out to other storage meanwhile. So:
850 * delete from cache even if there's another reference,
851 * after ensuring that the data has been saved to disk -
852 * since if the reference remains (rarer), it will be
853 * read from disk into another page. Splitting into two
854 * pages would be incorrect if swap supported "shared
855 * private" pages, but they are handled by tmpfs files.
856 *
857 * Note shmem_unuse already deleted a swappage from
858 * the swap cache, unless the move to filepage failed:
859 * in which case it left swappage in cache, lowered its
860 * swap count to pass quickly through the loops above,
861 * and now we must reincrement count to try again later.
862 */
863 if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) {
864 struct writeback_control wbc = {
865 .sync_mode = WB_SYNC_NONE,
866 };
867
868 swap_writepage(page, &wbc);
869 lock_page(page);
870 wait_on_page_writeback(page);
871 }
872 if (PageSwapCache(page)) {
873 if (shmem)
874 swap_duplicate(entry);
875 else
876 delete_from_swap_cache(page);
877 }
878
879 /*
880 * So we could skip searching mms once swap count went
881 * to 1, we did not mark any present ptes as dirty: must
882 * mark page dirty so shrink_list will preserve it.
883 */
884 SetPageDirty(page);
885 unlock_page(page);
886 page_cache_release(page);
887
888 /*
889 * Make sure that we aren't completely killing
890 * interactive performance.
891 */
892 cond_resched();
893 }
894
895 mmput(start_mm);
896 if (reset_overflow) {
897 printk(KERN_WARNING "swapoff: cleared swap entry overflow\n");
898 swap_overflow = 0;
899 }
900 return retval;
901}
902
903/*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700904 * After a successful try_to_unuse, if no swap is now in use, we know
905 * we can empty the mmlist. swap_lock must be held on entry and exit.
906 * Note that mmlist_lock nests inside swap_lock, and an mm must be
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907 * added to the mmlist just after page_duplicate - before would be racy.
908 */
909static void drain_mmlist(void)
910{
911 struct list_head *p, *next;
912 unsigned int i;
913
914 for (i = 0; i < nr_swapfiles; i++)
915 if (swap_info[i].inuse_pages)
916 return;
917 spin_lock(&mmlist_lock);
918 list_for_each_safe(p, next, &init_mm.mmlist)
919 list_del_init(p);
920 spin_unlock(&mmlist_lock);
921}
922
923/*
924 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
925 * corresponds to page offset `offset'.
926 */
927sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset)
928{
929 struct swap_extent *se = sis->curr_swap_extent;
930 struct swap_extent *start_se = se;
931
932 for ( ; ; ) {
933 struct list_head *lh;
934
935 if (se->start_page <= offset &&
936 offset < (se->start_page + se->nr_pages)) {
937 return se->start_block + (offset - se->start_page);
938 }
Hugh Dickins11d31882005-09-03 15:54:34 -0700939 lh = se->list.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700940 if (lh == &sis->extent_list)
Hugh Dickins11d31882005-09-03 15:54:34 -0700941 lh = lh->next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 se = list_entry(lh, struct swap_extent, list);
943 sis->curr_swap_extent = se;
944 BUG_ON(se == start_se); /* It *must* be present */
945 }
946}
947
Rafael J. Wysocki3aef83e2006-12-06 20:34:10 -0800948#ifdef CONFIG_SOFTWARE_SUSPEND
949/*
950 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
951 * corresponding to given index in swap_info (swap type).
952 */
953sector_t swapdev_block(int swap_type, pgoff_t offset)
954{
955 struct swap_info_struct *sis;
956
957 if (swap_type >= nr_swapfiles)
958 return 0;
959
960 sis = swap_info + swap_type;
961 return (sis->flags & SWP_WRITEOK) ? map_swap_page(sis, offset) : 0;
962}
963#endif /* CONFIG_SOFTWARE_SUSPEND */
964
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965/*
966 * Free all of a swapdev's extent information
967 */
968static void destroy_swap_extents(struct swap_info_struct *sis)
969{
970 while (!list_empty(&sis->extent_list)) {
971 struct swap_extent *se;
972
973 se = list_entry(sis->extent_list.next,
974 struct swap_extent, list);
975 list_del(&se->list);
976 kfree(se);
977 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700978}
979
980/*
981 * Add a block range (and the corresponding page range) into this swapdev's
Hugh Dickins11d31882005-09-03 15:54:34 -0700982 * extent list. The extent list is kept sorted in page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983 *
Hugh Dickins11d31882005-09-03 15:54:34 -0700984 * This function rather assumes that it is called in ascending page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985 */
986static int
987add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
988 unsigned long nr_pages, sector_t start_block)
989{
990 struct swap_extent *se;
991 struct swap_extent *new_se;
992 struct list_head *lh;
993
Hugh Dickins11d31882005-09-03 15:54:34 -0700994 lh = sis->extent_list.prev; /* The highest page extent */
995 if (lh != &sis->extent_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996 se = list_entry(lh, struct swap_extent, list);
Hugh Dickins11d31882005-09-03 15:54:34 -0700997 BUG_ON(se->start_page + se->nr_pages != start_page);
998 if (se->start_block + se->nr_pages == start_block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999 /* Merge it */
1000 se->nr_pages += nr_pages;
1001 return 0;
1002 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 }
1004
1005 /*
1006 * No merge. Insert a new extent, preserving ordering.
1007 */
1008 new_se = kmalloc(sizeof(*se), GFP_KERNEL);
1009 if (new_se == NULL)
1010 return -ENOMEM;
1011 new_se->start_page = start_page;
1012 new_se->nr_pages = nr_pages;
1013 new_se->start_block = start_block;
1014
Hugh Dickins11d31882005-09-03 15:54:34 -07001015 list_add_tail(&new_se->list, &sis->extent_list);
Hugh Dickins53092a72005-09-03 15:54:34 -07001016 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017}
1018
1019/*
1020 * A `swap extent' is a simple thing which maps a contiguous range of pages
1021 * onto a contiguous range of disk blocks. An ordered list of swap extents
1022 * is built at swapon time and is then used at swap_writepage/swap_readpage
1023 * time for locating where on disk a page belongs.
1024 *
1025 * If the swapfile is an S_ISBLK block device, a single extent is installed.
1026 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
1027 * swap files identically.
1028 *
1029 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
1030 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
1031 * swapfiles are handled *identically* after swapon time.
1032 *
1033 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
1034 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
1035 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
1036 * requirements, they are simply tossed out - we will never use those blocks
1037 * for swapping.
1038 *
Hugh Dickinsb0d9bcd2005-09-03 15:54:31 -07001039 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
1041 * which will scribble on the fs.
1042 *
1043 * The amount of disk space which a single swap extent represents varies.
1044 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
1045 * extents in the list. To avoid much list walking, we cache the previous
1046 * search location in `curr_swap_extent', and start new searches from there.
1047 * This is extremely effective. The average number of iterations in
1048 * map_swap_page() has been measured at about 0.3 per page. - akpm.
1049 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001050static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001051{
1052 struct inode *inode;
1053 unsigned blocks_per_page;
1054 unsigned long page_no;
1055 unsigned blkbits;
1056 sector_t probe_block;
1057 sector_t last_block;
Hugh Dickins53092a72005-09-03 15:54:34 -07001058 sector_t lowest_block = -1;
1059 sector_t highest_block = 0;
1060 int nr_extents = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061 int ret;
1062
1063 inode = sis->swap_file->f_mapping->host;
1064 if (S_ISBLK(inode->i_mode)) {
1065 ret = add_swap_extent(sis, 0, sis->max, 0);
Hugh Dickins53092a72005-09-03 15:54:34 -07001066 *span = sis->pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067 goto done;
1068 }
1069
1070 blkbits = inode->i_blkbits;
1071 blocks_per_page = PAGE_SIZE >> blkbits;
1072
1073 /*
1074 * Map all the blocks into the extent list. This code doesn't try
1075 * to be very smart.
1076 */
1077 probe_block = 0;
1078 page_no = 0;
1079 last_block = i_size_read(inode) >> blkbits;
1080 while ((probe_block + blocks_per_page) <= last_block &&
1081 page_no < sis->max) {
1082 unsigned block_in_page;
1083 sector_t first_block;
1084
1085 first_block = bmap(inode, probe_block);
1086 if (first_block == 0)
1087 goto bad_bmap;
1088
1089 /*
1090 * It must be PAGE_SIZE aligned on-disk
1091 */
1092 if (first_block & (blocks_per_page - 1)) {
1093 probe_block++;
1094 goto reprobe;
1095 }
1096
1097 for (block_in_page = 1; block_in_page < blocks_per_page;
1098 block_in_page++) {
1099 sector_t block;
1100
1101 block = bmap(inode, probe_block + block_in_page);
1102 if (block == 0)
1103 goto bad_bmap;
1104 if (block != first_block + block_in_page) {
1105 /* Discontiguity */
1106 probe_block++;
1107 goto reprobe;
1108 }
1109 }
1110
Hugh Dickins53092a72005-09-03 15:54:34 -07001111 first_block >>= (PAGE_SHIFT - blkbits);
1112 if (page_no) { /* exclude the header page */
1113 if (first_block < lowest_block)
1114 lowest_block = first_block;
1115 if (first_block > highest_block)
1116 highest_block = first_block;
1117 }
1118
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119 /*
1120 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1121 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001122 ret = add_swap_extent(sis, page_no, 1, first_block);
1123 if (ret < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124 goto out;
Hugh Dickins53092a72005-09-03 15:54:34 -07001125 nr_extents += ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126 page_no++;
1127 probe_block += blocks_per_page;
1128reprobe:
1129 continue;
1130 }
Hugh Dickins53092a72005-09-03 15:54:34 -07001131 ret = nr_extents;
1132 *span = 1 + highest_block - lowest_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133 if (page_no == 0)
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001134 page_no = 1; /* force Empty message */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001135 sis->max = page_no;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001136 sis->pages = page_no - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137 sis->highest_bit = page_no - 1;
1138done:
1139 sis->curr_swap_extent = list_entry(sis->extent_list.prev,
1140 struct swap_extent, list);
1141 goto out;
1142bad_bmap:
1143 printk(KERN_ERR "swapon: swapfile has holes\n");
1144 ret = -EINVAL;
1145out:
1146 return ret;
1147}
1148
1149#if 0 /* We don't need this yet */
1150#include <linux/backing-dev.h>
1151int page_queue_congested(struct page *page)
1152{
1153 struct backing_dev_info *bdi;
1154
1155 BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */
1156
1157 if (PageSwapCache(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07001158 swp_entry_t entry = { .val = page_private(page) };
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159 struct swap_info_struct *sis;
1160
1161 sis = get_swap_info_struct(swp_type(entry));
1162 bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info;
1163 } else
1164 bdi = page->mapping->backing_dev_info;
1165 return bdi_write_congested(bdi);
1166}
1167#endif
1168
1169asmlinkage long sys_swapoff(const char __user * specialfile)
1170{
1171 struct swap_info_struct * p = NULL;
1172 unsigned short *swap_map;
1173 struct file *swap_file, *victim;
1174 struct address_space *mapping;
1175 struct inode *inode;
1176 char * pathname;
1177 int i, type, prev;
1178 int err;
1179
1180 if (!capable(CAP_SYS_ADMIN))
1181 return -EPERM;
1182
1183 pathname = getname(specialfile);
1184 err = PTR_ERR(pathname);
1185 if (IS_ERR(pathname))
1186 goto out;
1187
1188 victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0);
1189 putname(pathname);
1190 err = PTR_ERR(victim);
1191 if (IS_ERR(victim))
1192 goto out;
1193
1194 mapping = victim->f_mapping;
1195 prev = -1;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001196 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197 for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
1198 p = swap_info + type;
1199 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
1200 if (p->swap_file->f_mapping == mapping)
1201 break;
1202 }
1203 prev = type;
1204 }
1205 if (type < 0) {
1206 err = -EINVAL;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001207 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001208 goto out_dput;
1209 }
1210 if (!security_vm_enough_memory(p->pages))
1211 vm_unacct_memory(p->pages);
1212 else {
1213 err = -ENOMEM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001214 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001215 goto out_dput;
1216 }
1217 if (prev < 0) {
1218 swap_list.head = p->next;
1219 } else {
1220 swap_info[prev].next = p->next;
1221 }
1222 if (type == swap_list.next) {
1223 /* just pick something that's safe... */
1224 swap_list.next = swap_list.head;
1225 }
1226 nr_swap_pages -= p->pages;
1227 total_swap_pages -= p->pages;
1228 p->flags &= ~SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001229 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -07001230
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231 current->flags |= PF_SWAPOFF;
1232 err = try_to_unuse(type);
1233 current->flags &= ~PF_SWAPOFF;
1234
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 if (err) {
1236 /* re-insert swap space back into swap_list */
Hugh Dickins5d337b92005-09-03 15:54:41 -07001237 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next)
1239 if (p->prio >= swap_info[i].prio)
1240 break;
1241 p->next = i;
1242 if (prev < 0)
1243 swap_list.head = swap_list.next = p - swap_info;
1244 else
1245 swap_info[prev].next = p - swap_info;
1246 nr_swap_pages += p->pages;
1247 total_swap_pages += p->pages;
1248 p->flags |= SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001249 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001250 goto out_dput;
1251 }
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001252
1253 /* wait for any unplug function to finish */
1254 down_write(&swap_unplug_sem);
1255 up_write(&swap_unplug_sem);
1256
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001257 destroy_swap_extents(p);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001258 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001259 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001260 drain_mmlist();
Hugh Dickins5d337b92005-09-03 15:54:41 -07001261
1262 /* wait for anyone still in scan_swap_map */
1263 p->highest_bit = 0; /* cuts scans short */
1264 while (p->flags >= SWP_SCANNING) {
1265 spin_unlock(&swap_lock);
Nishanth Aravamudan13e4b572005-09-10 00:27:25 -07001266 schedule_timeout_uninterruptible(1);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001267 spin_lock(&swap_lock);
1268 }
1269
Linus Torvalds1da177e2005-04-16 15:20:36 -07001270 swap_file = p->swap_file;
1271 p->swap_file = NULL;
1272 p->max = 0;
1273 swap_map = p->swap_map;
1274 p->swap_map = NULL;
1275 p->flags = 0;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001276 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001277 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278 vfree(swap_map);
1279 inode = mapping->host;
1280 if (S_ISBLK(inode->i_mode)) {
1281 struct block_device *bdev = I_BDEV(inode);
1282 set_blocksize(bdev, p->old_block_size);
1283 bd_release(bdev);
1284 } else {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001285 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286 inode->i_flags &= ~S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001287 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001288 }
1289 filp_close(swap_file, NULL);
1290 err = 0;
1291
1292out_dput:
1293 filp_close(victim, NULL);
1294out:
1295 return err;
1296}
1297
1298#ifdef CONFIG_PROC_FS
1299/* iterator */
1300static void *swap_start(struct seq_file *swap, loff_t *pos)
1301{
1302 struct swap_info_struct *ptr = swap_info;
1303 int i;
1304 loff_t l = *pos;
1305
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001306 mutex_lock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001308 if (!l)
1309 return SEQ_START_TOKEN;
1310
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311 for (i = 0; i < nr_swapfiles; i++, ptr++) {
1312 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1313 continue;
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001314 if (!--l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315 return ptr;
1316 }
1317
1318 return NULL;
1319}
1320
1321static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
1322{
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001323 struct swap_info_struct *ptr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001324 struct swap_info_struct *endptr = swap_info + nr_swapfiles;
1325
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001326 if (v == SEQ_START_TOKEN)
1327 ptr = swap_info;
1328 else {
1329 ptr = v;
1330 ptr++;
1331 }
1332
1333 for (; ptr < endptr; ptr++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1335 continue;
1336 ++*pos;
1337 return ptr;
1338 }
1339
1340 return NULL;
1341}
1342
1343static void swap_stop(struct seq_file *swap, void *v)
1344{
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001345 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346}
1347
1348static int swap_show(struct seq_file *swap, void *v)
1349{
1350 struct swap_info_struct *ptr = v;
1351 struct file *file;
1352 int len;
1353
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001354 if (ptr == SEQ_START_TOKEN) {
1355 seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1356 return 0;
1357 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358
1359 file = ptr->swap_file;
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001360 len = seq_path(swap, file->f_path.mnt, file->f_path.dentry, " \t\n\\");
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001361 seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362 len < 40 ? 40 - len : 1, " ",
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001363 S_ISBLK(file->f_path.dentry->d_inode->i_mode) ?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364 "partition" : "file\t",
1365 ptr->pages << (PAGE_SHIFT - 10),
1366 ptr->inuse_pages << (PAGE_SHIFT - 10),
1367 ptr->prio);
1368 return 0;
1369}
1370
Helge Deller15ad7cd2006-12-06 20:40:36 -08001371static const struct seq_operations swaps_op = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 .start = swap_start,
1373 .next = swap_next,
1374 .stop = swap_stop,
1375 .show = swap_show
1376};
1377
1378static int swaps_open(struct inode *inode, struct file *file)
1379{
1380 return seq_open(file, &swaps_op);
1381}
1382
Helge Deller15ad7cd2006-12-06 20:40:36 -08001383static const struct file_operations proc_swaps_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 .open = swaps_open,
1385 .read = seq_read,
1386 .llseek = seq_lseek,
1387 .release = seq_release,
1388};
1389
1390static int __init procswaps_init(void)
1391{
1392 struct proc_dir_entry *entry;
1393
1394 entry = create_proc_entry("swaps", 0, NULL);
1395 if (entry)
1396 entry->proc_fops = &proc_swaps_operations;
1397 return 0;
1398}
1399__initcall(procswaps_init);
1400#endif /* CONFIG_PROC_FS */
1401
1402/*
1403 * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
1404 *
1405 * The swapon system call
1406 */
1407asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
1408{
1409 struct swap_info_struct * p;
1410 char *name = NULL;
1411 struct block_device *bdev = NULL;
1412 struct file *swap_file = NULL;
1413 struct address_space *mapping;
1414 unsigned int type;
1415 int i, prev;
1416 int error;
1417 static int least_priority;
1418 union swap_header *swap_header = NULL;
1419 int swap_header_version;
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001420 unsigned int nr_good_pages = 0;
1421 int nr_extents = 0;
Hugh Dickins53092a72005-09-03 15:54:34 -07001422 sector_t span;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423 unsigned long maxpages = 1;
1424 int swapfilesize;
1425 unsigned short *swap_map;
1426 struct page *page = NULL;
1427 struct inode *inode = NULL;
1428 int did_down = 0;
1429
1430 if (!capable(CAP_SYS_ADMIN))
1431 return -EPERM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001432 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433 p = swap_info;
1434 for (type = 0 ; type < nr_swapfiles ; type++,p++)
1435 if (!(p->flags & SWP_USED))
1436 break;
1437 error = -EPERM;
Christoph Lameter06972122006-06-23 02:03:35 -07001438 if (type >= MAX_SWAPFILES) {
Hugh Dickins5d337b92005-09-03 15:54:41 -07001439 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001440 goto out;
1441 }
1442 if (type >= nr_swapfiles)
1443 nr_swapfiles = type+1;
1444 INIT_LIST_HEAD(&p->extent_list);
1445 p->flags = SWP_USED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001446 p->swap_file = NULL;
1447 p->old_block_size = 0;
1448 p->swap_map = NULL;
1449 p->lowest_bit = 0;
1450 p->highest_bit = 0;
1451 p->cluster_nr = 0;
1452 p->inuse_pages = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001453 p->next = -1;
1454 if (swap_flags & SWAP_FLAG_PREFER) {
1455 p->prio =
1456 (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT;
1457 } else {
1458 p->prio = --least_priority;
1459 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001460 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461 name = getname(specialfile);
1462 error = PTR_ERR(name);
1463 if (IS_ERR(name)) {
1464 name = NULL;
1465 goto bad_swap_2;
1466 }
1467 swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0);
1468 error = PTR_ERR(swap_file);
1469 if (IS_ERR(swap_file)) {
1470 swap_file = NULL;
1471 goto bad_swap_2;
1472 }
1473
1474 p->swap_file = swap_file;
1475 mapping = swap_file->f_mapping;
1476 inode = mapping->host;
1477
1478 error = -EBUSY;
1479 for (i = 0; i < nr_swapfiles; i++) {
1480 struct swap_info_struct *q = &swap_info[i];
1481
1482 if (i == type || !q->swap_file)
1483 continue;
1484 if (mapping == q->swap_file->f_mapping)
1485 goto bad_swap;
1486 }
1487
1488 error = -EINVAL;
1489 if (S_ISBLK(inode->i_mode)) {
1490 bdev = I_BDEV(inode);
1491 error = bd_claim(bdev, sys_swapon);
1492 if (error < 0) {
1493 bdev = NULL;
Rob Landleyf7b3a432005-09-22 21:44:27 -07001494 error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495 goto bad_swap;
1496 }
1497 p->old_block_size = block_size(bdev);
1498 error = set_blocksize(bdev, PAGE_SIZE);
1499 if (error < 0)
1500 goto bad_swap;
1501 p->bdev = bdev;
1502 } else if (S_ISREG(inode->i_mode)) {
1503 p->bdev = inode->i_sb->s_bdev;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001504 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 did_down = 1;
1506 if (IS_SWAPFILE(inode)) {
1507 error = -EBUSY;
1508 goto bad_swap;
1509 }
1510 } else {
1511 goto bad_swap;
1512 }
1513
1514 swapfilesize = i_size_read(inode) >> PAGE_SHIFT;
1515
1516 /*
1517 * Read the swap header.
1518 */
1519 if (!mapping->a_ops->readpage) {
1520 error = -EINVAL;
1521 goto bad_swap;
1522 }
Pekka Enberg090d2b12006-06-23 02:05:08 -07001523 page = read_mapping_page(mapping, 0, swap_file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524 if (IS_ERR(page)) {
1525 error = PTR_ERR(page);
1526 goto bad_swap;
1527 }
1528 wait_on_page_locked(page);
1529 if (!PageUptodate(page))
1530 goto bad_swap;
1531 kmap(page);
1532 swap_header = page_address(page);
1533
1534 if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
1535 swap_header_version = 1;
1536 else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
1537 swap_header_version = 2;
1538 else {
Jesper Juhle97a3112006-01-11 01:50:28 +01001539 printk(KERN_ERR "Unable to find swap-space signature\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540 error = -EINVAL;
1541 goto bad_swap;
1542 }
1543
1544 switch (swap_header_version) {
1545 case 1:
1546 printk(KERN_ERR "version 0 swap is no longer supported. "
1547 "Use mkswap -v1 %s\n", name);
1548 error = -EINVAL;
1549 goto bad_swap;
1550 case 2:
1551 /* Check the swap header's sub-version and the size of
1552 the swap file and bad block lists */
1553 if (swap_header->info.version != 1) {
1554 printk(KERN_WARNING
1555 "Unable to handle swap header version %d\n",
1556 swap_header->info.version);
1557 error = -EINVAL;
1558 goto bad_swap;
1559 }
1560
1561 p->lowest_bit = 1;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001562 p->cluster_next = 1;
1563
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564 /*
1565 * Find out how many pages are allowed for a single swap
1566 * device. There are two limiting factors: 1) the number of
1567 * bits for the swap offset in the swp_entry_t type and
1568 * 2) the number of bits in the a swap pte as defined by
1569 * the different architectures. In order to find the
1570 * largest possible bit mask a swap entry with swap type 0
1571 * and swap offset ~0UL is created, encoded to a swap pte,
1572 * decoded to a swp_entry_t again and finally the swap
1573 * offset is extracted. This will mask all the bits from
1574 * the initial ~0UL mask that can't be encoded in either
1575 * the swp_entry_t or the architecture definition of a
1576 * swap pte.
1577 */
1578 maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1;
1579 if (maxpages > swap_header->info.last_page)
1580 maxpages = swap_header->info.last_page;
1581 p->highest_bit = maxpages - 1;
1582
1583 error = -EINVAL;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001584 if (!maxpages)
1585 goto bad_swap;
Eric Sandeen5d1854e2006-12-06 20:33:06 -08001586 if (swapfilesize && maxpages > swapfilesize) {
1587 printk(KERN_WARNING
1588 "Swap area shorter than signature indicates\n");
1589 goto bad_swap;
1590 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001591 if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
1592 goto bad_swap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593 if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
1594 goto bad_swap;
Tobias Klausercd105df2006-01-08 01:00:59 -08001595
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596 /* OK, set up the swap map and apply the bad block list */
1597 if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) {
1598 error = -ENOMEM;
1599 goto bad_swap;
1600 }
1601
1602 error = 0;
1603 memset(p->swap_map, 0, maxpages * sizeof(short));
Tobias Klausercd105df2006-01-08 01:00:59 -08001604 for (i = 0; i < swap_header->info.nr_badpages; i++) {
1605 int page_nr = swap_header->info.badpages[i];
1606 if (page_nr <= 0 || page_nr >= swap_header->info.last_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001607 error = -EINVAL;
1608 else
Tobias Klausercd105df2006-01-08 01:00:59 -08001609 p->swap_map[page_nr] = SWAP_MAP_BAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001610 }
1611 nr_good_pages = swap_header->info.last_page -
1612 swap_header->info.nr_badpages -
1613 1 /* header page */;
Tobias Klausercd105df2006-01-08 01:00:59 -08001614 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001615 goto bad_swap;
1616 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001617
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001618 if (nr_good_pages) {
1619 p->swap_map[0] = SWAP_MAP_BAD;
1620 p->max = maxpages;
1621 p->pages = nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001622 nr_extents = setup_swap_extents(p, &span);
1623 if (nr_extents < 0) {
1624 error = nr_extents;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001625 goto bad_swap;
Hugh Dickins53092a72005-09-03 15:54:34 -07001626 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001627 nr_good_pages = p->pages;
1628 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629 if (!nr_good_pages) {
1630 printk(KERN_WARNING "Empty swap-file\n");
1631 error = -EINVAL;
1632 goto bad_swap;
1633 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001634
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001635 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001636 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 p->flags = SWP_ACTIVE;
1638 nr_swap_pages += nr_good_pages;
1639 total_swap_pages += nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001640
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001641 printk(KERN_INFO "Adding %uk swap on %s. "
Hugh Dickins53092a72005-09-03 15:54:34 -07001642 "Priority:%d extents:%d across:%lluk\n",
1643 nr_good_pages<<(PAGE_SHIFT-10), name, p->prio,
1644 nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645
1646 /* insert swap space into swap_list: */
1647 prev = -1;
1648 for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
1649 if (p->prio >= swap_info[i].prio) {
1650 break;
1651 }
1652 prev = i;
1653 }
1654 p->next = i;
1655 if (prev < 0) {
1656 swap_list.head = swap_list.next = p - swap_info;
1657 } else {
1658 swap_info[prev].next = p - swap_info;
1659 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001660 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001661 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001662 error = 0;
1663 goto out;
1664bad_swap:
1665 if (bdev) {
1666 set_blocksize(bdev, p->old_block_size);
1667 bd_release(bdev);
1668 }
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001669 destroy_swap_extents(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001670bad_swap_2:
Hugh Dickins5d337b92005-09-03 15:54:41 -07001671 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001672 swap_map = p->swap_map;
1673 p->swap_file = NULL;
1674 p->swap_map = NULL;
1675 p->flags = 0;
1676 if (!(swap_flags & SWAP_FLAG_PREFER))
1677 ++least_priority;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001678 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001679 vfree(swap_map);
1680 if (swap_file)
1681 filp_close(swap_file, NULL);
1682out:
1683 if (page && !IS_ERR(page)) {
1684 kunmap(page);
1685 page_cache_release(page);
1686 }
1687 if (name)
1688 putname(name);
1689 if (did_down) {
1690 if (!error)
1691 inode->i_flags |= S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001692 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693 }
1694 return error;
1695}
1696
1697void si_swapinfo(struct sysinfo *val)
1698{
1699 unsigned int i;
1700 unsigned long nr_to_be_unused = 0;
1701
Hugh Dickins5d337b92005-09-03 15:54:41 -07001702 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001703 for (i = 0; i < nr_swapfiles; i++) {
1704 if (!(swap_info[i].flags & SWP_USED) ||
1705 (swap_info[i].flags & SWP_WRITEOK))
1706 continue;
1707 nr_to_be_unused += swap_info[i].inuse_pages;
1708 }
1709 val->freeswap = nr_swap_pages + nr_to_be_unused;
1710 val->totalswap = total_swap_pages + nr_to_be_unused;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001711 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712}
1713
1714/*
1715 * Verify that a swap entry is valid and increment its swap map count.
1716 *
1717 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
1718 * "permanent", but will be reclaimed by the next swapoff.
1719 */
1720int swap_duplicate(swp_entry_t entry)
1721{
1722 struct swap_info_struct * p;
1723 unsigned long offset, type;
1724 int result = 0;
1725
Christoph Lameter06972122006-06-23 02:03:35 -07001726 if (is_migration_entry(entry))
1727 return 1;
1728
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729 type = swp_type(entry);
1730 if (type >= nr_swapfiles)
1731 goto bad_file;
1732 p = type + swap_info;
1733 offset = swp_offset(entry);
1734
Hugh Dickins5d337b92005-09-03 15:54:41 -07001735 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001736 if (offset < p->max && p->swap_map[offset]) {
1737 if (p->swap_map[offset] < SWAP_MAP_MAX - 1) {
1738 p->swap_map[offset]++;
1739 result = 1;
1740 } else if (p->swap_map[offset] <= SWAP_MAP_MAX) {
1741 if (swap_overflow++ < 5)
1742 printk(KERN_WARNING "swap_dup: swap entry overflow\n");
1743 p->swap_map[offset] = SWAP_MAP_MAX;
1744 result = 1;
1745 }
1746 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001747 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748out:
1749 return result;
1750
1751bad_file:
1752 printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
1753 goto out;
1754}
1755
1756struct swap_info_struct *
1757get_swap_info_struct(unsigned type)
1758{
1759 return &swap_info[type];
1760}
1761
1762/*
Hugh Dickins5d337b92005-09-03 15:54:41 -07001763 * swap_lock prevents swap_map being freed. Don't grab an extra
Linus Torvalds1da177e2005-04-16 15:20:36 -07001764 * reference on the swaphandle, it doesn't matter if it becomes unused.
1765 */
1766int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
1767{
Hugh Dickins3f9e7942006-09-29 02:01:26 -07001768 int our_page_cluster = page_cluster;
1769 int ret = 0, i = 1 << our_page_cluster;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001770 unsigned long toff;
1771 struct swap_info_struct *swapdev = swp_type(entry) + swap_info;
1772
Hugh Dickins3f9e7942006-09-29 02:01:26 -07001773 if (!our_page_cluster) /* no readahead */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001774 return 0;
Hugh Dickins3f9e7942006-09-29 02:01:26 -07001775 toff = (swp_offset(entry) >> our_page_cluster) << our_page_cluster;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001776 if (!toff) /* first page is swap header */
1777 toff++, i--;
1778 *offset = toff;
1779
Hugh Dickins5d337b92005-09-03 15:54:41 -07001780 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001781 do {
1782 /* Don't read-ahead past the end of the swap area */
1783 if (toff >= swapdev->max)
1784 break;
1785 /* Don't read in free or bad pages */
1786 if (!swapdev->swap_map[toff])
1787 break;
1788 if (swapdev->swap_map[toff] == SWAP_MAP_BAD)
1789 break;
1790 toff++;
1791 ret++;
1792 } while (--i);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001793 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001794 return ret;
1795}