blob: afae7b1f680b5f4140d305d2a5be7fb476f50fd5 [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. Wysockib0cb1a12007-07-29 23:24:36 +0200428#ifdef CONFIG_HIBERNATION
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800429/*
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. Wysocki7bf23682007-01-05 16:36:28 -0800437int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
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. Wysocki7bf23682007-01-05 16:36:28 -0800453 if (bdev_p)
454 *bdev_p = sis->bdev;
455
Rafael J. Wysocki6e1819d2006-03-23 03:00:03 -0800456 spin_unlock(&swap_lock);
457 return i;
458 }
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800459 if (bdev == sis->bdev) {
460 struct swap_extent *se;
461
462 se = list_entry(sis->extent_list.next,
463 struct swap_extent, list);
464 if (se->start_block == offset) {
Rafael J. Wysocki7bf23682007-01-05 16:36:28 -0800465 if (bdev_p)
466 *bdev_p = sis->bdev;
467
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800468 spin_unlock(&swap_lock);
469 bdput(bdev);
470 return i;
471 }
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800472 }
473 }
474 spin_unlock(&swap_lock);
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800475 if (bdev)
476 bdput(bdev);
477
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800478 return -ENODEV;
479}
480
481/*
482 * Return either the total number of swap pages of given type, or the number
483 * of free pages of that type (depending on @free)
484 *
485 * This is needed for software suspend
486 */
487unsigned int count_swap_pages(int type, int free)
488{
489 unsigned int n = 0;
490
491 if (type < nr_swapfiles) {
492 spin_lock(&swap_lock);
493 if (swap_info[type].flags & SWP_WRITEOK) {
494 n = swap_info[type].pages;
495 if (free)
496 n -= swap_info[type].inuse_pages;
497 }
498 spin_unlock(&swap_lock);
499 }
500 return n;
501}
502#endif
503
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504/*
Hugh Dickins72866f62005-10-29 18:15:55 -0700505 * No need to decide whether this PTE shares the swap entry with others,
506 * just let do_wp_page work it out if a write is requested later - to
507 * force COW, vm_page_prot omits write permission from any private vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 */
Hugh Dickins59bd2652008-02-07 00:13:48 -0800509static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 unsigned long addr, swp_entry_t entry, struct page *page)
511{
Hugh Dickins42946212005-10-29 18:16:05 -0700512 inc_mm_counter(vma->vm_mm, anon_rss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 get_page(page);
514 set_pte_at(vma->vm_mm, addr, pte,
515 pte_mkold(mk_pte(page, vma->vm_page_prot)));
516 page_add_anon_rmap(page, vma, addr);
517 swap_free(entry);
518 /*
519 * Move the page to the active list so it is not
520 * immediately swapped out again after swapon.
521 */
522 activate_page(page);
523}
524
525static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
526 unsigned long addr, unsigned long end,
527 swp_entry_t entry, struct page *page)
528{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 pte_t swp_pte = swp_entry_to_pte(entry);
Hugh Dickins705e87c2005-10-29 18:16:27 -0700530 pte_t *pte;
Hugh Dickins59bd2652008-02-07 00:13:48 -0800531 spinlock_t *ptl;
Hugh Dickins705e87c2005-10-29 18:16:27 -0700532 int found = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533
Hugh Dickins59bd2652008-02-07 00:13:48 -0800534 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 do {
536 /*
537 * swapoff spends a _lot_ of time in this loop!
538 * Test inline before going to call unuse_pte.
539 */
540 if (unlikely(pte_same(*pte, swp_pte))) {
Hugh Dickins59bd2652008-02-07 00:13:48 -0800541 unuse_pte(vma, pte++, addr, entry, page);
542 found = 1;
543 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 }
545 } while (pte++, addr += PAGE_SIZE, addr != end);
Hugh Dickins59bd2652008-02-07 00:13:48 -0800546 pte_unmap_unlock(pte - 1, ptl);
Hugh Dickins705e87c2005-10-29 18:16:27 -0700547 return found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548}
549
550static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
551 unsigned long addr, unsigned long end,
552 swp_entry_t entry, struct page *page)
553{
554 pmd_t *pmd;
555 unsigned long next;
556
557 pmd = pmd_offset(pud, addr);
558 do {
559 next = pmd_addr_end(addr, end);
560 if (pmd_none_or_clear_bad(pmd))
561 continue;
562 if (unuse_pte_range(vma, pmd, addr, next, entry, page))
563 return 1;
564 } while (pmd++, addr = next, addr != end);
565 return 0;
566}
567
568static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
569 unsigned long addr, unsigned long end,
570 swp_entry_t entry, struct page *page)
571{
572 pud_t *pud;
573 unsigned long next;
574
575 pud = pud_offset(pgd, addr);
576 do {
577 next = pud_addr_end(addr, end);
578 if (pud_none_or_clear_bad(pud))
579 continue;
580 if (unuse_pmd_range(vma, pud, addr, next, entry, page))
581 return 1;
582 } while (pud++, addr = next, addr != end);
583 return 0;
584}
585
586static int unuse_vma(struct vm_area_struct *vma,
587 swp_entry_t entry, struct page *page)
588{
589 pgd_t *pgd;
590 unsigned long addr, end, next;
591
592 if (page->mapping) {
593 addr = page_address_in_vma(page, vma);
594 if (addr == -EFAULT)
595 return 0;
596 else
597 end = addr + PAGE_SIZE;
598 } else {
599 addr = vma->vm_start;
600 end = vma->vm_end;
601 }
602
603 pgd = pgd_offset(vma->vm_mm, addr);
604 do {
605 next = pgd_addr_end(addr, end);
606 if (pgd_none_or_clear_bad(pgd))
607 continue;
608 if (unuse_pud_range(vma, pgd, addr, next, entry, page))
609 return 1;
610 } while (pgd++, addr = next, addr != end);
611 return 0;
612}
613
614static int unuse_mm(struct mm_struct *mm,
615 swp_entry_t entry, struct page *page)
616{
617 struct vm_area_struct *vma;
618
619 if (!down_read_trylock(&mm->mmap_sem)) {
620 /*
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700621 * Activate page so shrink_cache is unlikely to unmap its
622 * ptes while lock is dropped, so swapoff can make progress.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623 */
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700624 activate_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 unlock_page(page);
626 down_read(&mm->mmap_sem);
627 lock_page(page);
628 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 for (vma = mm->mmap; vma; vma = vma->vm_next) {
630 if (vma->anon_vma && unuse_vma(vma, entry, page))
631 break;
632 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 up_read(&mm->mmap_sem);
634 /*
635 * Currently unuse_mm cannot fail, but leave error handling
636 * at call sites for now, since we change it from time to time.
637 */
638 return 0;
639}
640
641/*
642 * Scan swap_map from current position to next entry still in use.
643 * Recycle to start on reaching the end, returning 0 when empty.
644 */
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700645static unsigned int find_next_to_unuse(struct swap_info_struct *si,
646 unsigned int prev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647{
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700648 unsigned int max = si->max;
649 unsigned int i = prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 int count;
651
652 /*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700653 * No need for swap_lock here: we're just looking
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654 * for whether an entry is in use, not modifying it; false
655 * hits are okay, and sys_swapoff() has already prevented new
Hugh Dickins5d337b92005-09-03 15:54:41 -0700656 * allocations from this area (while holding swap_lock).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657 */
658 for (;;) {
659 if (++i >= max) {
660 if (!prev) {
661 i = 0;
662 break;
663 }
664 /*
665 * No entries in use at top of swap_map,
666 * loop back to start and recheck there.
667 */
668 max = prev + 1;
669 prev = 0;
670 i = 1;
671 }
672 count = si->swap_map[i];
673 if (count && count != SWAP_MAP_BAD)
674 break;
675 }
676 return i;
677}
678
679/*
680 * We completely avoid races by reading each swap page in advance,
681 * and then search for the process using it. All the necessary
682 * page table adjustments can then be made atomically.
683 */
684static int try_to_unuse(unsigned int type)
685{
686 struct swap_info_struct * si = &swap_info[type];
687 struct mm_struct *start_mm;
688 unsigned short *swap_map;
689 unsigned short swcount;
690 struct page *page;
691 swp_entry_t entry;
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700692 unsigned int i = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 int retval = 0;
694 int reset_overflow = 0;
695 int shmem;
696
697 /*
698 * When searching mms for an entry, a good strategy is to
699 * start at the first mm we freed the previous entry from
700 * (though actually we don't notice whether we or coincidence
701 * freed the entry). Initialize this start_mm with a hold.
702 *
703 * A simpler strategy would be to start at the last mm we
704 * freed the previous entry from; but that would take less
705 * advantage of mmlist ordering, which clusters forked mms
706 * together, child after parent. If we race with dup_mmap(), we
707 * prefer to resolve parent before child, lest we miss entries
708 * duplicated after we scanned child: using last mm would invert
709 * that. Though it's only a serious concern when an overflowed
710 * swap count is reset from SWAP_MAP_MAX, preventing a rescan.
711 */
712 start_mm = &init_mm;
713 atomic_inc(&init_mm.mm_users);
714
715 /*
716 * Keep on scanning until all entries have gone. Usually,
717 * one pass through swap_map is enough, but not necessarily:
718 * there are races when an instance of an entry might be missed.
719 */
720 while ((i = find_next_to_unuse(si, i)) != 0) {
721 if (signal_pending(current)) {
722 retval = -EINTR;
723 break;
724 }
725
726 /*
727 * Get a page for the entry, using the existing swap
728 * cache page if there is one. Otherwise, get a clean
729 * page and read the swap into it.
730 */
731 swap_map = &si->swap_map[i];
732 entry = swp_entry(type, i);
Hugh Dickins02098fe2008-02-04 22:28:42 -0800733 page = read_swap_cache_async(entry,
734 GFP_HIGHUSER_MOVABLE, NULL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735 if (!page) {
736 /*
737 * Either swap_duplicate() failed because entry
738 * has been freed independently, and will not be
739 * reused since sys_swapoff() already disabled
740 * allocation from here, or alloc_page() failed.
741 */
742 if (!*swap_map)
743 continue;
744 retval = -ENOMEM;
745 break;
746 }
747
748 /*
749 * Don't hold on to start_mm if it looks like exiting.
750 */
751 if (atomic_read(&start_mm->mm_users) == 1) {
752 mmput(start_mm);
753 start_mm = &init_mm;
754 atomic_inc(&init_mm.mm_users);
755 }
756
757 /*
758 * Wait for and lock page. When do_swap_page races with
759 * try_to_unuse, do_swap_page can handle the fault much
760 * faster than try_to_unuse can locate the entry. This
761 * apparently redundant "wait_on_page_locked" lets try_to_unuse
762 * defer to do_swap_page in such a case - in some tests,
763 * do_swap_page and try_to_unuse repeatedly compete.
764 */
765 wait_on_page_locked(page);
766 wait_on_page_writeback(page);
767 lock_page(page);
768 wait_on_page_writeback(page);
769
770 /*
771 * Remove all references to entry.
772 * Whenever we reach init_mm, there's no address space
773 * to search, but use it as a reminder to search shmem.
774 */
775 shmem = 0;
776 swcount = *swap_map;
777 if (swcount > 1) {
778 if (start_mm == &init_mm)
779 shmem = shmem_unuse(entry, page);
780 else
781 retval = unuse_mm(start_mm, entry, page);
782 }
783 if (*swap_map > 1) {
784 int set_start_mm = (*swap_map >= swcount);
785 struct list_head *p = &start_mm->mmlist;
786 struct mm_struct *new_start_mm = start_mm;
787 struct mm_struct *prev_mm = start_mm;
788 struct mm_struct *mm;
789
790 atomic_inc(&new_start_mm->mm_users);
791 atomic_inc(&prev_mm->mm_users);
792 spin_lock(&mmlist_lock);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800793 while (*swap_map > 1 && !retval && !shmem &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 (p = p->next) != &start_mm->mmlist) {
795 mm = list_entry(p, struct mm_struct, mmlist);
Hugh Dickins70af7c52006-06-23 02:03:44 -0700796 if (!atomic_inc_not_zero(&mm->mm_users))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 spin_unlock(&mmlist_lock);
799 mmput(prev_mm);
800 prev_mm = mm;
801
802 cond_resched();
803
804 swcount = *swap_map;
805 if (swcount <= 1)
806 ;
807 else if (mm == &init_mm) {
808 set_start_mm = 1;
809 shmem = shmem_unuse(entry, page);
810 } else
811 retval = unuse_mm(mm, entry, page);
812 if (set_start_mm && *swap_map < swcount) {
813 mmput(new_start_mm);
814 atomic_inc(&mm->mm_users);
815 new_start_mm = mm;
816 set_start_mm = 0;
817 }
818 spin_lock(&mmlist_lock);
819 }
820 spin_unlock(&mmlist_lock);
821 mmput(prev_mm);
822 mmput(start_mm);
823 start_mm = new_start_mm;
824 }
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800825 if (shmem) {
826 /* page has already been unlocked and released */
827 if (shmem > 0)
828 continue;
829 retval = shmem;
830 break;
831 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 if (retval) {
833 unlock_page(page);
834 page_cache_release(page);
835 break;
836 }
837
838 /*
839 * How could swap count reach 0x7fff when the maximum
840 * pid is 0x7fff, and there's no way to repeat a swap
841 * page within an mm (except in shmem, where it's the
842 * shared object which takes the reference count)?
843 * We believe SWAP_MAP_MAX cannot occur in Linux 2.4.
844 *
845 * If that's wrong, then we should worry more about
846 * exit_mmap() and do_munmap() cases described above:
847 * we might be resetting SWAP_MAP_MAX too early here.
848 * We know "Undead"s can happen, they're okay, so don't
849 * report them; but do report if we reset SWAP_MAP_MAX.
850 */
851 if (*swap_map == SWAP_MAP_MAX) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700852 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700853 *swap_map = 1;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700854 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 reset_overflow = 1;
856 }
857
858 /*
859 * If a reference remains (rare), we would like to leave
860 * the page in the swap cache; but try_to_unmap could
861 * then re-duplicate the entry once we drop page lock,
862 * so we might loop indefinitely; also, that page could
863 * not be swapped out to other storage meanwhile. So:
864 * delete from cache even if there's another reference,
865 * after ensuring that the data has been saved to disk -
866 * since if the reference remains (rarer), it will be
867 * read from disk into another page. Splitting into two
868 * pages would be incorrect if swap supported "shared
869 * private" pages, but they are handled by tmpfs files.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870 */
871 if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) {
872 struct writeback_control wbc = {
873 .sync_mode = WB_SYNC_NONE,
874 };
875
876 swap_writepage(page, &wbc);
877 lock_page(page);
878 wait_on_page_writeback(page);
879 }
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800880 if (PageSwapCache(page))
881 delete_from_swap_cache(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882
883 /*
884 * So we could skip searching mms once swap count went
885 * to 1, we did not mark any present ptes as dirty: must
Anderson Briglia2706a1b2007-07-15 23:38:09 -0700886 * mark page dirty so shrink_page_list will preserve it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887 */
888 SetPageDirty(page);
889 unlock_page(page);
890 page_cache_release(page);
891
892 /*
893 * Make sure that we aren't completely killing
894 * interactive performance.
895 */
896 cond_resched();
897 }
898
899 mmput(start_mm);
900 if (reset_overflow) {
901 printk(KERN_WARNING "swapoff: cleared swap entry overflow\n");
902 swap_overflow = 0;
903 }
904 return retval;
905}
906
907/*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700908 * After a successful try_to_unuse, if no swap is now in use, we know
909 * we can empty the mmlist. swap_lock must be held on entry and exit.
910 * Note that mmlist_lock nests inside swap_lock, and an mm must be
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 * added to the mmlist just after page_duplicate - before would be racy.
912 */
913static void drain_mmlist(void)
914{
915 struct list_head *p, *next;
916 unsigned int i;
917
918 for (i = 0; i < nr_swapfiles; i++)
919 if (swap_info[i].inuse_pages)
920 return;
921 spin_lock(&mmlist_lock);
922 list_for_each_safe(p, next, &init_mm.mmlist)
923 list_del_init(p);
924 spin_unlock(&mmlist_lock);
925}
926
927/*
928 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
929 * corresponds to page offset `offset'.
930 */
931sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset)
932{
933 struct swap_extent *se = sis->curr_swap_extent;
934 struct swap_extent *start_se = se;
935
936 for ( ; ; ) {
937 struct list_head *lh;
938
939 if (se->start_page <= offset &&
940 offset < (se->start_page + se->nr_pages)) {
941 return se->start_block + (offset - se->start_page);
942 }
Hugh Dickins11d31882005-09-03 15:54:34 -0700943 lh = se->list.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 if (lh == &sis->extent_list)
Hugh Dickins11d31882005-09-03 15:54:34 -0700945 lh = lh->next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946 se = list_entry(lh, struct swap_extent, list);
947 sis->curr_swap_extent = se;
948 BUG_ON(se == start_se); /* It *must* be present */
949 }
950}
951
Rafael J. Wysockib0cb1a12007-07-29 23:24:36 +0200952#ifdef CONFIG_HIBERNATION
Rafael J. Wysocki3aef83e2006-12-06 20:34:10 -0800953/*
954 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
955 * corresponding to given index in swap_info (swap type).
956 */
957sector_t swapdev_block(int swap_type, pgoff_t offset)
958{
959 struct swap_info_struct *sis;
960
961 if (swap_type >= nr_swapfiles)
962 return 0;
963
964 sis = swap_info + swap_type;
965 return (sis->flags & SWP_WRITEOK) ? map_swap_page(sis, offset) : 0;
966}
Rafael J. Wysockib0cb1a12007-07-29 23:24:36 +0200967#endif /* CONFIG_HIBERNATION */
Rafael J. Wysocki3aef83e2006-12-06 20:34:10 -0800968
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969/*
970 * Free all of a swapdev's extent information
971 */
972static void destroy_swap_extents(struct swap_info_struct *sis)
973{
974 while (!list_empty(&sis->extent_list)) {
975 struct swap_extent *se;
976
977 se = list_entry(sis->extent_list.next,
978 struct swap_extent, list);
979 list_del(&se->list);
980 kfree(se);
981 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982}
983
984/*
985 * Add a block range (and the corresponding page range) into this swapdev's
Hugh Dickins11d31882005-09-03 15:54:34 -0700986 * extent list. The extent list is kept sorted in page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700987 *
Hugh Dickins11d31882005-09-03 15:54:34 -0700988 * This function rather assumes that it is called in ascending page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989 */
990static int
991add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
992 unsigned long nr_pages, sector_t start_block)
993{
994 struct swap_extent *se;
995 struct swap_extent *new_se;
996 struct list_head *lh;
997
Hugh Dickins11d31882005-09-03 15:54:34 -0700998 lh = sis->extent_list.prev; /* The highest page extent */
999 if (lh != &sis->extent_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000 se = list_entry(lh, struct swap_extent, list);
Hugh Dickins11d31882005-09-03 15:54:34 -07001001 BUG_ON(se->start_page + se->nr_pages != start_page);
1002 if (se->start_block + se->nr_pages == start_block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 /* Merge it */
1004 se->nr_pages += nr_pages;
1005 return 0;
1006 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001007 }
1008
1009 /*
1010 * No merge. Insert a new extent, preserving ordering.
1011 */
1012 new_se = kmalloc(sizeof(*se), GFP_KERNEL);
1013 if (new_se == NULL)
1014 return -ENOMEM;
1015 new_se->start_page = start_page;
1016 new_se->nr_pages = nr_pages;
1017 new_se->start_block = start_block;
1018
Hugh Dickins11d31882005-09-03 15:54:34 -07001019 list_add_tail(&new_se->list, &sis->extent_list);
Hugh Dickins53092a72005-09-03 15:54:34 -07001020 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001021}
1022
1023/*
1024 * A `swap extent' is a simple thing which maps a contiguous range of pages
1025 * onto a contiguous range of disk blocks. An ordered list of swap extents
1026 * is built at swapon time and is then used at swap_writepage/swap_readpage
1027 * time for locating where on disk a page belongs.
1028 *
1029 * If the swapfile is an S_ISBLK block device, a single extent is installed.
1030 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
1031 * swap files identically.
1032 *
1033 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
1034 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
1035 * swapfiles are handled *identically* after swapon time.
1036 *
1037 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
1038 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
1039 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
1040 * requirements, they are simply tossed out - we will never use those blocks
1041 * for swapping.
1042 *
Hugh Dickinsb0d9bcd2005-09-03 15:54:31 -07001043 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
1045 * which will scribble on the fs.
1046 *
1047 * The amount of disk space which a single swap extent represents varies.
1048 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
1049 * extents in the list. To avoid much list walking, we cache the previous
1050 * search location in `curr_swap_extent', and start new searches from there.
1051 * This is extremely effective. The average number of iterations in
1052 * map_swap_page() has been measured at about 0.3 per page. - akpm.
1053 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001054static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055{
1056 struct inode *inode;
1057 unsigned blocks_per_page;
1058 unsigned long page_no;
1059 unsigned blkbits;
1060 sector_t probe_block;
1061 sector_t last_block;
Hugh Dickins53092a72005-09-03 15:54:34 -07001062 sector_t lowest_block = -1;
1063 sector_t highest_block = 0;
1064 int nr_extents = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 int ret;
1066
1067 inode = sis->swap_file->f_mapping->host;
1068 if (S_ISBLK(inode->i_mode)) {
1069 ret = add_swap_extent(sis, 0, sis->max, 0);
Hugh Dickins53092a72005-09-03 15:54:34 -07001070 *span = sis->pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071 goto done;
1072 }
1073
1074 blkbits = inode->i_blkbits;
1075 blocks_per_page = PAGE_SIZE >> blkbits;
1076
1077 /*
1078 * Map all the blocks into the extent list. This code doesn't try
1079 * to be very smart.
1080 */
1081 probe_block = 0;
1082 page_no = 0;
1083 last_block = i_size_read(inode) >> blkbits;
1084 while ((probe_block + blocks_per_page) <= last_block &&
1085 page_no < sis->max) {
1086 unsigned block_in_page;
1087 sector_t first_block;
1088
1089 first_block = bmap(inode, probe_block);
1090 if (first_block == 0)
1091 goto bad_bmap;
1092
1093 /*
1094 * It must be PAGE_SIZE aligned on-disk
1095 */
1096 if (first_block & (blocks_per_page - 1)) {
1097 probe_block++;
1098 goto reprobe;
1099 }
1100
1101 for (block_in_page = 1; block_in_page < blocks_per_page;
1102 block_in_page++) {
1103 sector_t block;
1104
1105 block = bmap(inode, probe_block + block_in_page);
1106 if (block == 0)
1107 goto bad_bmap;
1108 if (block != first_block + block_in_page) {
1109 /* Discontiguity */
1110 probe_block++;
1111 goto reprobe;
1112 }
1113 }
1114
Hugh Dickins53092a72005-09-03 15:54:34 -07001115 first_block >>= (PAGE_SHIFT - blkbits);
1116 if (page_no) { /* exclude the header page */
1117 if (first_block < lowest_block)
1118 lowest_block = first_block;
1119 if (first_block > highest_block)
1120 highest_block = first_block;
1121 }
1122
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123 /*
1124 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1125 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001126 ret = add_swap_extent(sis, page_no, 1, first_block);
1127 if (ret < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128 goto out;
Hugh Dickins53092a72005-09-03 15:54:34 -07001129 nr_extents += ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130 page_no++;
1131 probe_block += blocks_per_page;
1132reprobe:
1133 continue;
1134 }
Hugh Dickins53092a72005-09-03 15:54:34 -07001135 ret = nr_extents;
1136 *span = 1 + highest_block - lowest_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137 if (page_no == 0)
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001138 page_no = 1; /* force Empty message */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139 sis->max = page_no;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001140 sis->pages = page_no - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141 sis->highest_bit = page_no - 1;
1142done:
1143 sis->curr_swap_extent = list_entry(sis->extent_list.prev,
1144 struct swap_extent, list);
1145 goto out;
1146bad_bmap:
1147 printk(KERN_ERR "swapon: swapfile has holes\n");
1148 ret = -EINVAL;
1149out:
1150 return ret;
1151}
1152
1153#if 0 /* We don't need this yet */
1154#include <linux/backing-dev.h>
1155int page_queue_congested(struct page *page)
1156{
1157 struct backing_dev_info *bdi;
1158
1159 BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */
1160
1161 if (PageSwapCache(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07001162 swp_entry_t entry = { .val = page_private(page) };
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163 struct swap_info_struct *sis;
1164
1165 sis = get_swap_info_struct(swp_type(entry));
1166 bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info;
1167 } else
1168 bdi = page->mapping->backing_dev_info;
1169 return bdi_write_congested(bdi);
1170}
1171#endif
1172
1173asmlinkage long sys_swapoff(const char __user * specialfile)
1174{
1175 struct swap_info_struct * p = NULL;
1176 unsigned short *swap_map;
1177 struct file *swap_file, *victim;
1178 struct address_space *mapping;
1179 struct inode *inode;
1180 char * pathname;
1181 int i, type, prev;
1182 int err;
1183
1184 if (!capable(CAP_SYS_ADMIN))
1185 return -EPERM;
1186
1187 pathname = getname(specialfile);
1188 err = PTR_ERR(pathname);
1189 if (IS_ERR(pathname))
1190 goto out;
1191
1192 victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0);
1193 putname(pathname);
1194 err = PTR_ERR(victim);
1195 if (IS_ERR(victim))
1196 goto out;
1197
1198 mapping = victim->f_mapping;
1199 prev = -1;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001200 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201 for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
1202 p = swap_info + type;
1203 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
1204 if (p->swap_file->f_mapping == mapping)
1205 break;
1206 }
1207 prev = type;
1208 }
1209 if (type < 0) {
1210 err = -EINVAL;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001211 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212 goto out_dput;
1213 }
1214 if (!security_vm_enough_memory(p->pages))
1215 vm_unacct_memory(p->pages);
1216 else {
1217 err = -ENOMEM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001218 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219 goto out_dput;
1220 }
1221 if (prev < 0) {
1222 swap_list.head = p->next;
1223 } else {
1224 swap_info[prev].next = p->next;
1225 }
1226 if (type == swap_list.next) {
1227 /* just pick something that's safe... */
1228 swap_list.next = swap_list.head;
1229 }
1230 nr_swap_pages -= p->pages;
1231 total_swap_pages -= p->pages;
1232 p->flags &= ~SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001233 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -07001234
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 current->flags |= PF_SWAPOFF;
1236 err = try_to_unuse(type);
1237 current->flags &= ~PF_SWAPOFF;
1238
Linus Torvalds1da177e2005-04-16 15:20:36 -07001239 if (err) {
1240 /* re-insert swap space back into swap_list */
Hugh Dickins5d337b92005-09-03 15:54:41 -07001241 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242 for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next)
1243 if (p->prio >= swap_info[i].prio)
1244 break;
1245 p->next = i;
1246 if (prev < 0)
1247 swap_list.head = swap_list.next = p - swap_info;
1248 else
1249 swap_info[prev].next = p - swap_info;
1250 nr_swap_pages += p->pages;
1251 total_swap_pages += p->pages;
1252 p->flags |= SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001253 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254 goto out_dput;
1255 }
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001256
1257 /* wait for any unplug function to finish */
1258 down_write(&swap_unplug_sem);
1259 up_write(&swap_unplug_sem);
1260
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001261 destroy_swap_extents(p);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001262 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001263 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264 drain_mmlist();
Hugh Dickins5d337b92005-09-03 15:54:41 -07001265
1266 /* wait for anyone still in scan_swap_map */
1267 p->highest_bit = 0; /* cuts scans short */
1268 while (p->flags >= SWP_SCANNING) {
1269 spin_unlock(&swap_lock);
Nishanth Aravamudan13e4b572005-09-10 00:27:25 -07001270 schedule_timeout_uninterruptible(1);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001271 spin_lock(&swap_lock);
1272 }
1273
Linus Torvalds1da177e2005-04-16 15:20:36 -07001274 swap_file = p->swap_file;
1275 p->swap_file = NULL;
1276 p->max = 0;
1277 swap_map = p->swap_map;
1278 p->swap_map = NULL;
1279 p->flags = 0;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001280 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001281 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001282 vfree(swap_map);
1283 inode = mapping->host;
1284 if (S_ISBLK(inode->i_mode)) {
1285 struct block_device *bdev = I_BDEV(inode);
1286 set_blocksize(bdev, p->old_block_size);
1287 bd_release(bdev);
1288 } else {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001289 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290 inode->i_flags &= ~S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001291 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001292 }
1293 filp_close(swap_file, NULL);
1294 err = 0;
1295
1296out_dput:
1297 filp_close(victim, NULL);
1298out:
1299 return err;
1300}
1301
1302#ifdef CONFIG_PROC_FS
1303/* iterator */
1304static void *swap_start(struct seq_file *swap, loff_t *pos)
1305{
1306 struct swap_info_struct *ptr = swap_info;
1307 int i;
1308 loff_t l = *pos;
1309
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001310 mutex_lock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001312 if (!l)
1313 return SEQ_START_TOKEN;
1314
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315 for (i = 0; i < nr_swapfiles; i++, ptr++) {
1316 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1317 continue;
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001318 if (!--l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319 return ptr;
1320 }
1321
1322 return NULL;
1323}
1324
1325static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
1326{
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001327 struct swap_info_struct *ptr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328 struct swap_info_struct *endptr = swap_info + nr_swapfiles;
1329
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001330 if (v == SEQ_START_TOKEN)
1331 ptr = swap_info;
1332 else {
1333 ptr = v;
1334 ptr++;
1335 }
1336
1337 for (; ptr < endptr; ptr++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1339 continue;
1340 ++*pos;
1341 return ptr;
1342 }
1343
1344 return NULL;
1345}
1346
1347static void swap_stop(struct seq_file *swap, void *v)
1348{
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001349 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001350}
1351
1352static int swap_show(struct seq_file *swap, void *v)
1353{
1354 struct swap_info_struct *ptr = v;
1355 struct file *file;
1356 int len;
1357
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001358 if (ptr == SEQ_START_TOKEN) {
1359 seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1360 return 0;
1361 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362
1363 file = ptr->swap_file;
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001364 len = seq_path(swap, file->f_path.mnt, file->f_path.dentry, " \t\n\\");
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001365 seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366 len < 40 ? 40 - len : 1, " ",
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001367 S_ISBLK(file->f_path.dentry->d_inode->i_mode) ?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368 "partition" : "file\t",
1369 ptr->pages << (PAGE_SHIFT - 10),
1370 ptr->inuse_pages << (PAGE_SHIFT - 10),
1371 ptr->prio);
1372 return 0;
1373}
1374
Helge Deller15ad7cd2006-12-06 20:40:36 -08001375static const struct seq_operations swaps_op = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 .start = swap_start,
1377 .next = swap_next,
1378 .stop = swap_stop,
1379 .show = swap_show
1380};
1381
1382static int swaps_open(struct inode *inode, struct file *file)
1383{
1384 return seq_open(file, &swaps_op);
1385}
1386
Helge Deller15ad7cd2006-12-06 20:40:36 -08001387static const struct file_operations proc_swaps_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388 .open = swaps_open,
1389 .read = seq_read,
1390 .llseek = seq_lseek,
1391 .release = seq_release,
1392};
1393
1394static int __init procswaps_init(void)
1395{
1396 struct proc_dir_entry *entry;
1397
1398 entry = create_proc_entry("swaps", 0, NULL);
1399 if (entry)
1400 entry->proc_fops = &proc_swaps_operations;
1401 return 0;
1402}
1403__initcall(procswaps_init);
1404#endif /* CONFIG_PROC_FS */
1405
1406/*
1407 * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
1408 *
1409 * The swapon system call
1410 */
1411asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
1412{
1413 struct swap_info_struct * p;
1414 char *name = NULL;
1415 struct block_device *bdev = NULL;
1416 struct file *swap_file = NULL;
1417 struct address_space *mapping;
1418 unsigned int type;
1419 int i, prev;
1420 int error;
1421 static int least_priority;
1422 union swap_header *swap_header = NULL;
1423 int swap_header_version;
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001424 unsigned int nr_good_pages = 0;
1425 int nr_extents = 0;
Hugh Dickins53092a72005-09-03 15:54:34 -07001426 sector_t span;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427 unsigned long maxpages = 1;
1428 int swapfilesize;
1429 unsigned short *swap_map;
1430 struct page *page = NULL;
1431 struct inode *inode = NULL;
1432 int did_down = 0;
1433
1434 if (!capable(CAP_SYS_ADMIN))
1435 return -EPERM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001436 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437 p = swap_info;
1438 for (type = 0 ; type < nr_swapfiles ; type++,p++)
1439 if (!(p->flags & SWP_USED))
1440 break;
1441 error = -EPERM;
Christoph Lameter06972122006-06-23 02:03:35 -07001442 if (type >= MAX_SWAPFILES) {
Hugh Dickins5d337b92005-09-03 15:54:41 -07001443 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001444 goto out;
1445 }
1446 if (type >= nr_swapfiles)
1447 nr_swapfiles = type+1;
1448 INIT_LIST_HEAD(&p->extent_list);
1449 p->flags = SWP_USED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450 p->swap_file = NULL;
1451 p->old_block_size = 0;
1452 p->swap_map = NULL;
1453 p->lowest_bit = 0;
1454 p->highest_bit = 0;
1455 p->cluster_nr = 0;
1456 p->inuse_pages = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001457 p->next = -1;
1458 if (swap_flags & SWAP_FLAG_PREFER) {
1459 p->prio =
1460 (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT;
1461 } else {
1462 p->prio = --least_priority;
1463 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001464 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465 name = getname(specialfile);
1466 error = PTR_ERR(name);
1467 if (IS_ERR(name)) {
1468 name = NULL;
1469 goto bad_swap_2;
1470 }
1471 swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0);
1472 error = PTR_ERR(swap_file);
1473 if (IS_ERR(swap_file)) {
1474 swap_file = NULL;
1475 goto bad_swap_2;
1476 }
1477
1478 p->swap_file = swap_file;
1479 mapping = swap_file->f_mapping;
1480 inode = mapping->host;
1481
1482 error = -EBUSY;
1483 for (i = 0; i < nr_swapfiles; i++) {
1484 struct swap_info_struct *q = &swap_info[i];
1485
1486 if (i == type || !q->swap_file)
1487 continue;
1488 if (mapping == q->swap_file->f_mapping)
1489 goto bad_swap;
1490 }
1491
1492 error = -EINVAL;
1493 if (S_ISBLK(inode->i_mode)) {
1494 bdev = I_BDEV(inode);
1495 error = bd_claim(bdev, sys_swapon);
1496 if (error < 0) {
1497 bdev = NULL;
Rob Landleyf7b3a432005-09-22 21:44:27 -07001498 error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499 goto bad_swap;
1500 }
1501 p->old_block_size = block_size(bdev);
1502 error = set_blocksize(bdev, PAGE_SIZE);
1503 if (error < 0)
1504 goto bad_swap;
1505 p->bdev = bdev;
1506 } else if (S_ISREG(inode->i_mode)) {
1507 p->bdev = inode->i_sb->s_bdev;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001508 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509 did_down = 1;
1510 if (IS_SWAPFILE(inode)) {
1511 error = -EBUSY;
1512 goto bad_swap;
1513 }
1514 } else {
1515 goto bad_swap;
1516 }
1517
1518 swapfilesize = i_size_read(inode) >> PAGE_SHIFT;
1519
1520 /*
1521 * Read the swap header.
1522 */
1523 if (!mapping->a_ops->readpage) {
1524 error = -EINVAL;
1525 goto bad_swap;
1526 }
Pekka Enberg090d2b12006-06-23 02:05:08 -07001527 page = read_mapping_page(mapping, 0, swap_file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528 if (IS_ERR(page)) {
1529 error = PTR_ERR(page);
1530 goto bad_swap;
1531 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001532 kmap(page);
1533 swap_header = page_address(page);
1534
1535 if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
1536 swap_header_version = 1;
1537 else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
1538 swap_header_version = 2;
1539 else {
Jesper Juhle97a3112006-01-11 01:50:28 +01001540 printk(KERN_ERR "Unable to find swap-space signature\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001541 error = -EINVAL;
1542 goto bad_swap;
1543 }
1544
1545 switch (swap_header_version) {
1546 case 1:
1547 printk(KERN_ERR "version 0 swap is no longer supported. "
1548 "Use mkswap -v1 %s\n", name);
1549 error = -EINVAL;
1550 goto bad_swap;
1551 case 2:
1552 /* Check the swap header's sub-version and the size of
1553 the swap file and bad block lists */
1554 if (swap_header->info.version != 1) {
1555 printk(KERN_WARNING
1556 "Unable to handle swap header version %d\n",
1557 swap_header->info.version);
1558 error = -EINVAL;
1559 goto bad_swap;
1560 }
1561
1562 p->lowest_bit = 1;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001563 p->cluster_next = 1;
1564
Linus Torvalds1da177e2005-04-16 15:20:36 -07001565 /*
1566 * Find out how many pages are allowed for a single swap
1567 * device. There are two limiting factors: 1) the number of
1568 * bits for the swap offset in the swp_entry_t type and
1569 * 2) the number of bits in the a swap pte as defined by
1570 * the different architectures. In order to find the
1571 * largest possible bit mask a swap entry with swap type 0
1572 * and swap offset ~0UL is created, encoded to a swap pte,
1573 * decoded to a swp_entry_t again and finally the swap
1574 * offset is extracted. This will mask all the bits from
1575 * the initial ~0UL mask that can't be encoded in either
1576 * the swp_entry_t or the architecture definition of a
1577 * swap pte.
1578 */
1579 maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1;
1580 if (maxpages > swap_header->info.last_page)
1581 maxpages = swap_header->info.last_page;
1582 p->highest_bit = maxpages - 1;
1583
1584 error = -EINVAL;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001585 if (!maxpages)
1586 goto bad_swap;
Eric Sandeen5d1854e2006-12-06 20:33:06 -08001587 if (swapfilesize && maxpages > swapfilesize) {
1588 printk(KERN_WARNING
1589 "Swap area shorter than signature indicates\n");
1590 goto bad_swap;
1591 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001592 if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
1593 goto bad_swap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594 if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
1595 goto bad_swap;
Tobias Klausercd105df2006-01-08 01:00:59 -08001596
Linus Torvalds1da177e2005-04-16 15:20:36 -07001597 /* OK, set up the swap map and apply the bad block list */
1598 if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) {
1599 error = -ENOMEM;
1600 goto bad_swap;
1601 }
1602
1603 error = 0;
1604 memset(p->swap_map, 0, maxpages * sizeof(short));
Tobias Klausercd105df2006-01-08 01:00:59 -08001605 for (i = 0; i < swap_header->info.nr_badpages; i++) {
1606 int page_nr = swap_header->info.badpages[i];
1607 if (page_nr <= 0 || page_nr >= swap_header->info.last_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001608 error = -EINVAL;
1609 else
Tobias Klausercd105df2006-01-08 01:00:59 -08001610 p->swap_map[page_nr] = SWAP_MAP_BAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611 }
1612 nr_good_pages = swap_header->info.last_page -
1613 swap_header->info.nr_badpages -
1614 1 /* header page */;
Tobias Klausercd105df2006-01-08 01:00:59 -08001615 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616 goto bad_swap;
1617 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001618
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001619 if (nr_good_pages) {
1620 p->swap_map[0] = SWAP_MAP_BAD;
1621 p->max = maxpages;
1622 p->pages = nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001623 nr_extents = setup_swap_extents(p, &span);
1624 if (nr_extents < 0) {
1625 error = nr_extents;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001626 goto bad_swap;
Hugh Dickins53092a72005-09-03 15:54:34 -07001627 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001628 nr_good_pages = p->pages;
1629 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001630 if (!nr_good_pages) {
1631 printk(KERN_WARNING "Empty swap-file\n");
1632 error = -EINVAL;
1633 goto bad_swap;
1634 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001636 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001637 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638 p->flags = SWP_ACTIVE;
1639 nr_swap_pages += nr_good_pages;
1640 total_swap_pages += nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001641
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001642 printk(KERN_INFO "Adding %uk swap on %s. "
Hugh Dickins53092a72005-09-03 15:54:34 -07001643 "Priority:%d extents:%d across:%lluk\n",
1644 nr_good_pages<<(PAGE_SHIFT-10), name, p->prio,
1645 nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646
1647 /* insert swap space into swap_list: */
1648 prev = -1;
1649 for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
1650 if (p->prio >= swap_info[i].prio) {
1651 break;
1652 }
1653 prev = i;
1654 }
1655 p->next = i;
1656 if (prev < 0) {
1657 swap_list.head = swap_list.next = p - swap_info;
1658 } else {
1659 swap_info[prev].next = p - swap_info;
1660 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001661 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001662 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001663 error = 0;
1664 goto out;
1665bad_swap:
1666 if (bdev) {
1667 set_blocksize(bdev, p->old_block_size);
1668 bd_release(bdev);
1669 }
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001670 destroy_swap_extents(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001671bad_swap_2:
Hugh Dickins5d337b92005-09-03 15:54:41 -07001672 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673 swap_map = p->swap_map;
1674 p->swap_file = NULL;
1675 p->swap_map = NULL;
1676 p->flags = 0;
1677 if (!(swap_flags & SWAP_FLAG_PREFER))
1678 ++least_priority;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001679 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680 vfree(swap_map);
1681 if (swap_file)
1682 filp_close(swap_file, NULL);
1683out:
1684 if (page && !IS_ERR(page)) {
1685 kunmap(page);
1686 page_cache_release(page);
1687 }
1688 if (name)
1689 putname(name);
1690 if (did_down) {
1691 if (!error)
1692 inode->i_flags |= S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001693 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001694 }
1695 return error;
1696}
1697
1698void si_swapinfo(struct sysinfo *val)
1699{
1700 unsigned int i;
1701 unsigned long nr_to_be_unused = 0;
1702
Hugh Dickins5d337b92005-09-03 15:54:41 -07001703 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704 for (i = 0; i < nr_swapfiles; i++) {
1705 if (!(swap_info[i].flags & SWP_USED) ||
1706 (swap_info[i].flags & SWP_WRITEOK))
1707 continue;
1708 nr_to_be_unused += swap_info[i].inuse_pages;
1709 }
1710 val->freeswap = nr_swap_pages + nr_to_be_unused;
1711 val->totalswap = total_swap_pages + nr_to_be_unused;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001712 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001713}
1714
1715/*
1716 * Verify that a swap entry is valid and increment its swap map count.
1717 *
1718 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
1719 * "permanent", but will be reclaimed by the next swapoff.
1720 */
1721int swap_duplicate(swp_entry_t entry)
1722{
1723 struct swap_info_struct * p;
1724 unsigned long offset, type;
1725 int result = 0;
1726
Christoph Lameter06972122006-06-23 02:03:35 -07001727 if (is_migration_entry(entry))
1728 return 1;
1729
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 type = swp_type(entry);
1731 if (type >= nr_swapfiles)
1732 goto bad_file;
1733 p = type + swap_info;
1734 offset = swp_offset(entry);
1735
Hugh Dickins5d337b92005-09-03 15:54:41 -07001736 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 if (offset < p->max && p->swap_map[offset]) {
1738 if (p->swap_map[offset] < SWAP_MAP_MAX - 1) {
1739 p->swap_map[offset]++;
1740 result = 1;
1741 } else if (p->swap_map[offset] <= SWAP_MAP_MAX) {
1742 if (swap_overflow++ < 5)
1743 printk(KERN_WARNING "swap_dup: swap entry overflow\n");
1744 p->swap_map[offset] = SWAP_MAP_MAX;
1745 result = 1;
1746 }
1747 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001748 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001749out:
1750 return result;
1751
1752bad_file:
1753 printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
1754 goto out;
1755}
1756
1757struct swap_info_struct *
1758get_swap_info_struct(unsigned type)
1759{
1760 return &swap_info[type];
1761}
1762
1763/*
Hugh Dickins5d337b92005-09-03 15:54:41 -07001764 * swap_lock prevents swap_map being freed. Don't grab an extra
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765 * reference on the swaphandle, it doesn't matter if it becomes unused.
1766 */
1767int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
1768{
Hugh Dickins89528982008-02-04 22:28:45 -08001769 struct swap_info_struct *si;
Hugh Dickins3f9e7942006-09-29 02:01:26 -07001770 int our_page_cluster = page_cluster;
Hugh Dickins89528982008-02-04 22:28:45 -08001771 pgoff_t target, toff;
1772 pgoff_t base, end;
1773 int nr_pages = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001774
Hugh Dickins3f9e7942006-09-29 02:01:26 -07001775 if (!our_page_cluster) /* no readahead */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001776 return 0;
Hugh Dickins89528982008-02-04 22:28:45 -08001777
1778 si = &swap_info[swp_type(entry)];
1779 target = swp_offset(entry);
1780 base = (target >> our_page_cluster) << our_page_cluster;
1781 end = base + (1 << our_page_cluster);
1782 if (!base) /* first page is swap header */
1783 base++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784
Hugh Dickins5d337b92005-09-03 15:54:41 -07001785 spin_lock(&swap_lock);
Hugh Dickins89528982008-02-04 22:28:45 -08001786 if (end > si->max) /* don't go beyond end of map */
1787 end = si->max;
1788
1789 /* Count contiguous allocated slots above our target */
1790 for (toff = target; ++toff < end; nr_pages++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791 /* Don't read in free or bad pages */
Hugh Dickins89528982008-02-04 22:28:45 -08001792 if (!si->swap_map[toff])
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793 break;
Hugh Dickins89528982008-02-04 22:28:45 -08001794 if (si->swap_map[toff] == SWAP_MAP_BAD)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001795 break;
Hugh Dickins89528982008-02-04 22:28:45 -08001796 }
1797 /* Count contiguous allocated slots below our target */
1798 for (toff = target; --toff >= base; nr_pages++) {
1799 /* Don't read in free or bad pages */
1800 if (!si->swap_map[toff])
1801 break;
1802 if (si->swap_map[toff] == SWAP_MAP_BAD)
1803 break;
1804 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001805 spin_unlock(&swap_lock);
Hugh Dickins89528982008-02-04 22:28:45 -08001806
1807 /*
1808 * Indicate starting offset, and return number of pages to get:
1809 * if only 1, say 0, since there's then no readahead to be done.
1810 */
1811 *offset = ++toff;
1812 return nr_pages? ++nr_pages: 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813}