blob: 2bfacbac0f4c2d9d79c64549565835d45a64fb2b [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>
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
948/*
949 * Free all of a swapdev's extent information
950 */
951static void destroy_swap_extents(struct swap_info_struct *sis)
952{
953 while (!list_empty(&sis->extent_list)) {
954 struct swap_extent *se;
955
956 se = list_entry(sis->extent_list.next,
957 struct swap_extent, list);
958 list_del(&se->list);
959 kfree(se);
960 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961}
962
963/*
964 * Add a block range (and the corresponding page range) into this swapdev's
Hugh Dickins11d31882005-09-03 15:54:34 -0700965 * extent list. The extent list is kept sorted in page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700966 *
Hugh Dickins11d31882005-09-03 15:54:34 -0700967 * This function rather assumes that it is called in ascending page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 */
969static int
970add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
971 unsigned long nr_pages, sector_t start_block)
972{
973 struct swap_extent *se;
974 struct swap_extent *new_se;
975 struct list_head *lh;
976
Hugh Dickins11d31882005-09-03 15:54:34 -0700977 lh = sis->extent_list.prev; /* The highest page extent */
978 if (lh != &sis->extent_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979 se = list_entry(lh, struct swap_extent, list);
Hugh Dickins11d31882005-09-03 15:54:34 -0700980 BUG_ON(se->start_page + se->nr_pages != start_page);
981 if (se->start_block + se->nr_pages == start_block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982 /* Merge it */
983 se->nr_pages += nr_pages;
984 return 0;
985 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986 }
987
988 /*
989 * No merge. Insert a new extent, preserving ordering.
990 */
991 new_se = kmalloc(sizeof(*se), GFP_KERNEL);
992 if (new_se == NULL)
993 return -ENOMEM;
994 new_se->start_page = start_page;
995 new_se->nr_pages = nr_pages;
996 new_se->start_block = start_block;
997
Hugh Dickins11d31882005-09-03 15:54:34 -0700998 list_add_tail(&new_se->list, &sis->extent_list);
Hugh Dickins53092a72005-09-03 15:54:34 -0700999 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000}
1001
1002/*
1003 * A `swap extent' is a simple thing which maps a contiguous range of pages
1004 * onto a contiguous range of disk blocks. An ordered list of swap extents
1005 * is built at swapon time and is then used at swap_writepage/swap_readpage
1006 * time for locating where on disk a page belongs.
1007 *
1008 * If the swapfile is an S_ISBLK block device, a single extent is installed.
1009 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
1010 * swap files identically.
1011 *
1012 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
1013 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
1014 * swapfiles are handled *identically* after swapon time.
1015 *
1016 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
1017 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
1018 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
1019 * requirements, they are simply tossed out - we will never use those blocks
1020 * for swapping.
1021 *
Hugh Dickinsb0d9bcd2005-09-03 15:54:31 -07001022 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
Linus Torvalds1da177e2005-04-16 15:20:36 -07001023 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
1024 * which will scribble on the fs.
1025 *
1026 * The amount of disk space which a single swap extent represents varies.
1027 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
1028 * extents in the list. To avoid much list walking, we cache the previous
1029 * search location in `curr_swap_extent', and start new searches from there.
1030 * This is extremely effective. The average number of iterations in
1031 * map_swap_page() has been measured at about 0.3 per page. - akpm.
1032 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001033static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001034{
1035 struct inode *inode;
1036 unsigned blocks_per_page;
1037 unsigned long page_no;
1038 unsigned blkbits;
1039 sector_t probe_block;
1040 sector_t last_block;
Hugh Dickins53092a72005-09-03 15:54:34 -07001041 sector_t lowest_block = -1;
1042 sector_t highest_block = 0;
1043 int nr_extents = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 int ret;
1045
1046 inode = sis->swap_file->f_mapping->host;
1047 if (S_ISBLK(inode->i_mode)) {
1048 ret = add_swap_extent(sis, 0, sis->max, 0);
Hugh Dickins53092a72005-09-03 15:54:34 -07001049 *span = sis->pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050 goto done;
1051 }
1052
1053 blkbits = inode->i_blkbits;
1054 blocks_per_page = PAGE_SIZE >> blkbits;
1055
1056 /*
1057 * Map all the blocks into the extent list. This code doesn't try
1058 * to be very smart.
1059 */
1060 probe_block = 0;
1061 page_no = 0;
1062 last_block = i_size_read(inode) >> blkbits;
1063 while ((probe_block + blocks_per_page) <= last_block &&
1064 page_no < sis->max) {
1065 unsigned block_in_page;
1066 sector_t first_block;
1067
1068 first_block = bmap(inode, probe_block);
1069 if (first_block == 0)
1070 goto bad_bmap;
1071
1072 /*
1073 * It must be PAGE_SIZE aligned on-disk
1074 */
1075 if (first_block & (blocks_per_page - 1)) {
1076 probe_block++;
1077 goto reprobe;
1078 }
1079
1080 for (block_in_page = 1; block_in_page < blocks_per_page;
1081 block_in_page++) {
1082 sector_t block;
1083
1084 block = bmap(inode, probe_block + block_in_page);
1085 if (block == 0)
1086 goto bad_bmap;
1087 if (block != first_block + block_in_page) {
1088 /* Discontiguity */
1089 probe_block++;
1090 goto reprobe;
1091 }
1092 }
1093
Hugh Dickins53092a72005-09-03 15:54:34 -07001094 first_block >>= (PAGE_SHIFT - blkbits);
1095 if (page_no) { /* exclude the header page */
1096 if (first_block < lowest_block)
1097 lowest_block = first_block;
1098 if (first_block > highest_block)
1099 highest_block = first_block;
1100 }
1101
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102 /*
1103 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1104 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001105 ret = add_swap_extent(sis, page_no, 1, first_block);
1106 if (ret < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107 goto out;
Hugh Dickins53092a72005-09-03 15:54:34 -07001108 nr_extents += ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109 page_no++;
1110 probe_block += blocks_per_page;
1111reprobe:
1112 continue;
1113 }
Hugh Dickins53092a72005-09-03 15:54:34 -07001114 ret = nr_extents;
1115 *span = 1 + highest_block - lowest_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116 if (page_no == 0)
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001117 page_no = 1; /* force Empty message */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001118 sis->max = page_no;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001119 sis->pages = page_no - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001120 sis->highest_bit = page_no - 1;
1121done:
1122 sis->curr_swap_extent = list_entry(sis->extent_list.prev,
1123 struct swap_extent, list);
1124 goto out;
1125bad_bmap:
1126 printk(KERN_ERR "swapon: swapfile has holes\n");
1127 ret = -EINVAL;
1128out:
1129 return ret;
1130}
1131
1132#if 0 /* We don't need this yet */
1133#include <linux/backing-dev.h>
1134int page_queue_congested(struct page *page)
1135{
1136 struct backing_dev_info *bdi;
1137
1138 BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */
1139
1140 if (PageSwapCache(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07001141 swp_entry_t entry = { .val = page_private(page) };
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142 struct swap_info_struct *sis;
1143
1144 sis = get_swap_info_struct(swp_type(entry));
1145 bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info;
1146 } else
1147 bdi = page->mapping->backing_dev_info;
1148 return bdi_write_congested(bdi);
1149}
1150#endif
1151
1152asmlinkage long sys_swapoff(const char __user * specialfile)
1153{
1154 struct swap_info_struct * p = NULL;
1155 unsigned short *swap_map;
1156 struct file *swap_file, *victim;
1157 struct address_space *mapping;
1158 struct inode *inode;
1159 char * pathname;
1160 int i, type, prev;
1161 int err;
1162
1163 if (!capable(CAP_SYS_ADMIN))
1164 return -EPERM;
1165
1166 pathname = getname(specialfile);
1167 err = PTR_ERR(pathname);
1168 if (IS_ERR(pathname))
1169 goto out;
1170
1171 victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0);
1172 putname(pathname);
1173 err = PTR_ERR(victim);
1174 if (IS_ERR(victim))
1175 goto out;
1176
1177 mapping = victim->f_mapping;
1178 prev = -1;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001179 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
1181 p = swap_info + type;
1182 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
1183 if (p->swap_file->f_mapping == mapping)
1184 break;
1185 }
1186 prev = type;
1187 }
1188 if (type < 0) {
1189 err = -EINVAL;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001190 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191 goto out_dput;
1192 }
1193 if (!security_vm_enough_memory(p->pages))
1194 vm_unacct_memory(p->pages);
1195 else {
1196 err = -ENOMEM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001197 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198 goto out_dput;
1199 }
1200 if (prev < 0) {
1201 swap_list.head = p->next;
1202 } else {
1203 swap_info[prev].next = p->next;
1204 }
1205 if (type == swap_list.next) {
1206 /* just pick something that's safe... */
1207 swap_list.next = swap_list.head;
1208 }
1209 nr_swap_pages -= p->pages;
1210 total_swap_pages -= p->pages;
1211 p->flags &= ~SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001212 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -07001213
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214 current->flags |= PF_SWAPOFF;
1215 err = try_to_unuse(type);
1216 current->flags &= ~PF_SWAPOFF;
1217
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218 if (err) {
1219 /* re-insert swap space back into swap_list */
Hugh Dickins5d337b92005-09-03 15:54:41 -07001220 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221 for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next)
1222 if (p->prio >= swap_info[i].prio)
1223 break;
1224 p->next = i;
1225 if (prev < 0)
1226 swap_list.head = swap_list.next = p - swap_info;
1227 else
1228 swap_info[prev].next = p - swap_info;
1229 nr_swap_pages += p->pages;
1230 total_swap_pages += p->pages;
1231 p->flags |= SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001232 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233 goto out_dput;
1234 }
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001235
1236 /* wait for any unplug function to finish */
1237 down_write(&swap_unplug_sem);
1238 up_write(&swap_unplug_sem);
1239
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001240 destroy_swap_extents(p);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001241 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001242 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001243 drain_mmlist();
Hugh Dickins5d337b92005-09-03 15:54:41 -07001244
1245 /* wait for anyone still in scan_swap_map */
1246 p->highest_bit = 0; /* cuts scans short */
1247 while (p->flags >= SWP_SCANNING) {
1248 spin_unlock(&swap_lock);
Nishanth Aravamudan13e4b572005-09-10 00:27:25 -07001249 schedule_timeout_uninterruptible(1);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001250 spin_lock(&swap_lock);
1251 }
1252
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253 swap_file = p->swap_file;
1254 p->swap_file = NULL;
1255 p->max = 0;
1256 swap_map = p->swap_map;
1257 p->swap_map = NULL;
1258 p->flags = 0;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001259 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001260 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001261 vfree(swap_map);
1262 inode = mapping->host;
1263 if (S_ISBLK(inode->i_mode)) {
1264 struct block_device *bdev = I_BDEV(inode);
1265 set_blocksize(bdev, p->old_block_size);
1266 bd_release(bdev);
1267 } else {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001268 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001269 inode->i_flags &= ~S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001270 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271 }
1272 filp_close(swap_file, NULL);
1273 err = 0;
1274
1275out_dput:
1276 filp_close(victim, NULL);
1277out:
1278 return err;
1279}
1280
1281#ifdef CONFIG_PROC_FS
1282/* iterator */
1283static void *swap_start(struct seq_file *swap, loff_t *pos)
1284{
1285 struct swap_info_struct *ptr = swap_info;
1286 int i;
1287 loff_t l = *pos;
1288
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001289 mutex_lock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001291 if (!l)
1292 return SEQ_START_TOKEN;
1293
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294 for (i = 0; i < nr_swapfiles; i++, ptr++) {
1295 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1296 continue;
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001297 if (!--l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298 return ptr;
1299 }
1300
1301 return NULL;
1302}
1303
1304static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
1305{
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001306 struct swap_info_struct *ptr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307 struct swap_info_struct *endptr = swap_info + nr_swapfiles;
1308
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001309 if (v == SEQ_START_TOKEN)
1310 ptr = swap_info;
1311 else {
1312 ptr = v;
1313 ptr++;
1314 }
1315
1316 for (; ptr < endptr; ptr++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001317 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1318 continue;
1319 ++*pos;
1320 return ptr;
1321 }
1322
1323 return NULL;
1324}
1325
1326static void swap_stop(struct seq_file *swap, void *v)
1327{
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001328 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001329}
1330
1331static int swap_show(struct seq_file *swap, void *v)
1332{
1333 struct swap_info_struct *ptr = v;
1334 struct file *file;
1335 int len;
1336
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001337 if (ptr == SEQ_START_TOKEN) {
1338 seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1339 return 0;
1340 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341
1342 file = ptr->swap_file;
1343 len = seq_path(swap, file->f_vfsmnt, file->f_dentry, " \t\n\\");
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001344 seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345 len < 40 ? 40 - len : 1, " ",
1346 S_ISBLK(file->f_dentry->d_inode->i_mode) ?
1347 "partition" : "file\t",
1348 ptr->pages << (PAGE_SHIFT - 10),
1349 ptr->inuse_pages << (PAGE_SHIFT - 10),
1350 ptr->prio);
1351 return 0;
1352}
1353
1354static struct seq_operations swaps_op = {
1355 .start = swap_start,
1356 .next = swap_next,
1357 .stop = swap_stop,
1358 .show = swap_show
1359};
1360
1361static int swaps_open(struct inode *inode, struct file *file)
1362{
1363 return seq_open(file, &swaps_op);
1364}
1365
1366static struct file_operations proc_swaps_operations = {
1367 .open = swaps_open,
1368 .read = seq_read,
1369 .llseek = seq_lseek,
1370 .release = seq_release,
1371};
1372
1373static int __init procswaps_init(void)
1374{
1375 struct proc_dir_entry *entry;
1376
1377 entry = create_proc_entry("swaps", 0, NULL);
1378 if (entry)
1379 entry->proc_fops = &proc_swaps_operations;
1380 return 0;
1381}
1382__initcall(procswaps_init);
1383#endif /* CONFIG_PROC_FS */
1384
1385/*
1386 * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
1387 *
1388 * The swapon system call
1389 */
1390asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
1391{
1392 struct swap_info_struct * p;
1393 char *name = NULL;
1394 struct block_device *bdev = NULL;
1395 struct file *swap_file = NULL;
1396 struct address_space *mapping;
1397 unsigned int type;
1398 int i, prev;
1399 int error;
1400 static int least_priority;
1401 union swap_header *swap_header = NULL;
1402 int swap_header_version;
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001403 unsigned int nr_good_pages = 0;
1404 int nr_extents = 0;
Hugh Dickins53092a72005-09-03 15:54:34 -07001405 sector_t span;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406 unsigned long maxpages = 1;
1407 int swapfilesize;
1408 unsigned short *swap_map;
1409 struct page *page = NULL;
1410 struct inode *inode = NULL;
1411 int did_down = 0;
1412
1413 if (!capable(CAP_SYS_ADMIN))
1414 return -EPERM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001415 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416 p = swap_info;
1417 for (type = 0 ; type < nr_swapfiles ; type++,p++)
1418 if (!(p->flags & SWP_USED))
1419 break;
1420 error = -EPERM;
Christoph Lameter06972122006-06-23 02:03:35 -07001421 if (type >= MAX_SWAPFILES) {
Hugh Dickins5d337b92005-09-03 15:54:41 -07001422 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423 goto out;
1424 }
1425 if (type >= nr_swapfiles)
1426 nr_swapfiles = type+1;
1427 INIT_LIST_HEAD(&p->extent_list);
1428 p->flags = SWP_USED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429 p->swap_file = NULL;
1430 p->old_block_size = 0;
1431 p->swap_map = NULL;
1432 p->lowest_bit = 0;
1433 p->highest_bit = 0;
1434 p->cluster_nr = 0;
1435 p->inuse_pages = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001436 p->next = -1;
1437 if (swap_flags & SWAP_FLAG_PREFER) {
1438 p->prio =
1439 (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT;
1440 } else {
1441 p->prio = --least_priority;
1442 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001443 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001444 name = getname(specialfile);
1445 error = PTR_ERR(name);
1446 if (IS_ERR(name)) {
1447 name = NULL;
1448 goto bad_swap_2;
1449 }
1450 swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0);
1451 error = PTR_ERR(swap_file);
1452 if (IS_ERR(swap_file)) {
1453 swap_file = NULL;
1454 goto bad_swap_2;
1455 }
1456
1457 p->swap_file = swap_file;
1458 mapping = swap_file->f_mapping;
1459 inode = mapping->host;
1460
1461 error = -EBUSY;
1462 for (i = 0; i < nr_swapfiles; i++) {
1463 struct swap_info_struct *q = &swap_info[i];
1464
1465 if (i == type || !q->swap_file)
1466 continue;
1467 if (mapping == q->swap_file->f_mapping)
1468 goto bad_swap;
1469 }
1470
1471 error = -EINVAL;
1472 if (S_ISBLK(inode->i_mode)) {
1473 bdev = I_BDEV(inode);
1474 error = bd_claim(bdev, sys_swapon);
1475 if (error < 0) {
1476 bdev = NULL;
Rob Landleyf7b3a432005-09-22 21:44:27 -07001477 error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001478 goto bad_swap;
1479 }
1480 p->old_block_size = block_size(bdev);
1481 error = set_blocksize(bdev, PAGE_SIZE);
1482 if (error < 0)
1483 goto bad_swap;
1484 p->bdev = bdev;
1485 } else if (S_ISREG(inode->i_mode)) {
1486 p->bdev = inode->i_sb->s_bdev;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001487 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001488 did_down = 1;
1489 if (IS_SWAPFILE(inode)) {
1490 error = -EBUSY;
1491 goto bad_swap;
1492 }
1493 } else {
1494 goto bad_swap;
1495 }
1496
1497 swapfilesize = i_size_read(inode) >> PAGE_SHIFT;
1498
1499 /*
1500 * Read the swap header.
1501 */
1502 if (!mapping->a_ops->readpage) {
1503 error = -EINVAL;
1504 goto bad_swap;
1505 }
Pekka Enberg090d2b12006-06-23 02:05:08 -07001506 page = read_mapping_page(mapping, 0, swap_file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507 if (IS_ERR(page)) {
1508 error = PTR_ERR(page);
1509 goto bad_swap;
1510 }
1511 wait_on_page_locked(page);
1512 if (!PageUptodate(page))
1513 goto bad_swap;
1514 kmap(page);
1515 swap_header = page_address(page);
1516
1517 if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
1518 swap_header_version = 1;
1519 else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
1520 swap_header_version = 2;
1521 else {
Jesper Juhle97a3112006-01-11 01:50:28 +01001522 printk(KERN_ERR "Unable to find swap-space signature\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523 error = -EINVAL;
1524 goto bad_swap;
1525 }
1526
1527 switch (swap_header_version) {
1528 case 1:
1529 printk(KERN_ERR "version 0 swap is no longer supported. "
1530 "Use mkswap -v1 %s\n", name);
1531 error = -EINVAL;
1532 goto bad_swap;
1533 case 2:
1534 /* Check the swap header's sub-version and the size of
1535 the swap file and bad block lists */
1536 if (swap_header->info.version != 1) {
1537 printk(KERN_WARNING
1538 "Unable to handle swap header version %d\n",
1539 swap_header->info.version);
1540 error = -EINVAL;
1541 goto bad_swap;
1542 }
1543
1544 p->lowest_bit = 1;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001545 p->cluster_next = 1;
1546
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547 /*
1548 * Find out how many pages are allowed for a single swap
1549 * device. There are two limiting factors: 1) the number of
1550 * bits for the swap offset in the swp_entry_t type and
1551 * 2) the number of bits in the a swap pte as defined by
1552 * the different architectures. In order to find the
1553 * largest possible bit mask a swap entry with swap type 0
1554 * and swap offset ~0UL is created, encoded to a swap pte,
1555 * decoded to a swp_entry_t again and finally the swap
1556 * offset is extracted. This will mask all the bits from
1557 * the initial ~0UL mask that can't be encoded in either
1558 * the swp_entry_t or the architecture definition of a
1559 * swap pte.
1560 */
1561 maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1;
1562 if (maxpages > swap_header->info.last_page)
1563 maxpages = swap_header->info.last_page;
1564 p->highest_bit = maxpages - 1;
1565
1566 error = -EINVAL;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001567 if (!maxpages)
1568 goto bad_swap;
Eric Sandeen5d1854e2006-12-06 20:33:06 -08001569 if (swapfilesize && maxpages > swapfilesize) {
1570 printk(KERN_WARNING
1571 "Swap area shorter than signature indicates\n");
1572 goto bad_swap;
1573 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001574 if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
1575 goto bad_swap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001576 if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
1577 goto bad_swap;
Tobias Klausercd105df2006-01-08 01:00:59 -08001578
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579 /* OK, set up the swap map and apply the bad block list */
1580 if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) {
1581 error = -ENOMEM;
1582 goto bad_swap;
1583 }
1584
1585 error = 0;
1586 memset(p->swap_map, 0, maxpages * sizeof(short));
Tobias Klausercd105df2006-01-08 01:00:59 -08001587 for (i = 0; i < swap_header->info.nr_badpages; i++) {
1588 int page_nr = swap_header->info.badpages[i];
1589 if (page_nr <= 0 || page_nr >= swap_header->info.last_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590 error = -EINVAL;
1591 else
Tobias Klausercd105df2006-01-08 01:00:59 -08001592 p->swap_map[page_nr] = SWAP_MAP_BAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593 }
1594 nr_good_pages = swap_header->info.last_page -
1595 swap_header->info.nr_badpages -
1596 1 /* header page */;
Tobias Klausercd105df2006-01-08 01:00:59 -08001597 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001598 goto bad_swap;
1599 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001600
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001601 if (nr_good_pages) {
1602 p->swap_map[0] = SWAP_MAP_BAD;
1603 p->max = maxpages;
1604 p->pages = nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001605 nr_extents = setup_swap_extents(p, &span);
1606 if (nr_extents < 0) {
1607 error = nr_extents;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001608 goto bad_swap;
Hugh Dickins53092a72005-09-03 15:54:34 -07001609 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001610 nr_good_pages = p->pages;
1611 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001612 if (!nr_good_pages) {
1613 printk(KERN_WARNING "Empty swap-file\n");
1614 error = -EINVAL;
1615 goto bad_swap;
1616 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001618 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001619 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001620 p->flags = SWP_ACTIVE;
1621 nr_swap_pages += nr_good_pages;
1622 total_swap_pages += nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001623
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001624 printk(KERN_INFO "Adding %uk swap on %s. "
Hugh Dickins53092a72005-09-03 15:54:34 -07001625 "Priority:%d extents:%d across:%lluk\n",
1626 nr_good_pages<<(PAGE_SHIFT-10), name, p->prio,
1627 nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628
1629 /* insert swap space into swap_list: */
1630 prev = -1;
1631 for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
1632 if (p->prio >= swap_info[i].prio) {
1633 break;
1634 }
1635 prev = i;
1636 }
1637 p->next = i;
1638 if (prev < 0) {
1639 swap_list.head = swap_list.next = p - swap_info;
1640 } else {
1641 swap_info[prev].next = p - swap_info;
1642 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001643 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001644 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 error = 0;
1646 goto out;
1647bad_swap:
1648 if (bdev) {
1649 set_blocksize(bdev, p->old_block_size);
1650 bd_release(bdev);
1651 }
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001652 destroy_swap_extents(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001653bad_swap_2:
Hugh Dickins5d337b92005-09-03 15:54:41 -07001654 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655 swap_map = p->swap_map;
1656 p->swap_file = NULL;
1657 p->swap_map = NULL;
1658 p->flags = 0;
1659 if (!(swap_flags & SWAP_FLAG_PREFER))
1660 ++least_priority;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001661 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001662 vfree(swap_map);
1663 if (swap_file)
1664 filp_close(swap_file, NULL);
1665out:
1666 if (page && !IS_ERR(page)) {
1667 kunmap(page);
1668 page_cache_release(page);
1669 }
1670 if (name)
1671 putname(name);
1672 if (did_down) {
1673 if (!error)
1674 inode->i_flags |= S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001675 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001676 }
1677 return error;
1678}
1679
1680void si_swapinfo(struct sysinfo *val)
1681{
1682 unsigned int i;
1683 unsigned long nr_to_be_unused = 0;
1684
Hugh Dickins5d337b92005-09-03 15:54:41 -07001685 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686 for (i = 0; i < nr_swapfiles; i++) {
1687 if (!(swap_info[i].flags & SWP_USED) ||
1688 (swap_info[i].flags & SWP_WRITEOK))
1689 continue;
1690 nr_to_be_unused += swap_info[i].inuse_pages;
1691 }
1692 val->freeswap = nr_swap_pages + nr_to_be_unused;
1693 val->totalswap = total_swap_pages + nr_to_be_unused;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001694 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695}
1696
1697/*
1698 * Verify that a swap entry is valid and increment its swap map count.
1699 *
1700 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
1701 * "permanent", but will be reclaimed by the next swapoff.
1702 */
1703int swap_duplicate(swp_entry_t entry)
1704{
1705 struct swap_info_struct * p;
1706 unsigned long offset, type;
1707 int result = 0;
1708
Christoph Lameter06972122006-06-23 02:03:35 -07001709 if (is_migration_entry(entry))
1710 return 1;
1711
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712 type = swp_type(entry);
1713 if (type >= nr_swapfiles)
1714 goto bad_file;
1715 p = type + swap_info;
1716 offset = swp_offset(entry);
1717
Hugh Dickins5d337b92005-09-03 15:54:41 -07001718 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001719 if (offset < p->max && p->swap_map[offset]) {
1720 if (p->swap_map[offset] < SWAP_MAP_MAX - 1) {
1721 p->swap_map[offset]++;
1722 result = 1;
1723 } else if (p->swap_map[offset] <= SWAP_MAP_MAX) {
1724 if (swap_overflow++ < 5)
1725 printk(KERN_WARNING "swap_dup: swap entry overflow\n");
1726 p->swap_map[offset] = SWAP_MAP_MAX;
1727 result = 1;
1728 }
1729 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001730 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731out:
1732 return result;
1733
1734bad_file:
1735 printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
1736 goto out;
1737}
1738
1739struct swap_info_struct *
1740get_swap_info_struct(unsigned type)
1741{
1742 return &swap_info[type];
1743}
1744
1745/*
Hugh Dickins5d337b92005-09-03 15:54:41 -07001746 * swap_lock prevents swap_map being freed. Don't grab an extra
Linus Torvalds1da177e2005-04-16 15:20:36 -07001747 * reference on the swaphandle, it doesn't matter if it becomes unused.
1748 */
1749int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
1750{
Hugh Dickins3f9e7942006-09-29 02:01:26 -07001751 int our_page_cluster = page_cluster;
1752 int ret = 0, i = 1 << our_page_cluster;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001753 unsigned long toff;
1754 struct swap_info_struct *swapdev = swp_type(entry) + swap_info;
1755
Hugh Dickins3f9e7942006-09-29 02:01:26 -07001756 if (!our_page_cluster) /* no readahead */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757 return 0;
Hugh Dickins3f9e7942006-09-29 02:01:26 -07001758 toff = (swp_offset(entry) >> our_page_cluster) << our_page_cluster;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001759 if (!toff) /* first page is swap header */
1760 toff++, i--;
1761 *offset = toff;
1762
Hugh Dickins5d337b92005-09-03 15:54:41 -07001763 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001764 do {
1765 /* Don't read-ahead past the end of the swap area */
1766 if (toff >= swapdev->max)
1767 break;
1768 /* Don't read in free or bad pages */
1769 if (!swapdev->swap_map[toff])
1770 break;
1771 if (swapdev->swap_map[toff] == SWAP_MAP_BAD)
1772 break;
1773 toff++;
1774 ret++;
1775 } while (--i);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001776 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777 return ret;
1778}