blob: 1e330f2998fa259d2733f73f4c50ce0d649c5dc0 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/swapfile.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 * Swap reorganised 29.12.95, Stephen Tweedie
6 */
7
Linus Torvalds1da177e2005-04-16 15:20:36 -07008#include <linux/mm.h>
9#include <linux/hugetlb.h>
10#include <linux/mman.h>
11#include <linux/slab.h>
12#include <linux/kernel_stat.h>
13#include <linux/swap.h>
14#include <linux/vmalloc.h>
15#include <linux/pagemap.h>
16#include <linux/namei.h>
17#include <linux/shm.h>
18#include <linux/blkdev.h>
19#include <linux/writeback.h>
20#include <linux/proc_fs.h>
21#include <linux/seq_file.h>
22#include <linux/init.h>
23#include <linux/module.h>
24#include <linux/rmap.h>
25#include <linux/security.h>
26#include <linux/backing-dev.h>
Ingo Molnarfc0abb12006-01-18 17:42:33 -080027#include <linux/mutex.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080028#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/syscalls.h>
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080030#include <linux/memcontrol.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
32#include <asm/pgtable.h>
33#include <asm/tlbflush.h>
34#include <linux/swapops.h>
35
Adrian Bunk7c363b82008-07-25 19:46:24 -070036static DEFINE_SPINLOCK(swap_lock);
37static unsigned int nr_swapfiles;
Linus Torvalds1da177e2005-04-16 15:20:36 -070038long total_swap_pages;
39static int swap_overflow;
Hugh Dickins78ecba02008-07-23 21:28:23 -070040static int least_priority;
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
Linus Torvalds1da177e2005-04-16 15:20:36 -070042static const char Bad_file[] = "Bad swap file entry ";
43static const char Unused_file[] = "Unused swap file entry ";
44static const char Bad_offset[] = "Bad swap offset entry ";
45static const char Unused_offset[] = "Unused swap offset entry ";
46
Adrian Bunk7c363b82008-07-25 19:46:24 -070047static struct swap_list_t swap_list = {-1, -1};
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
Rafael J. Wysockif577eb32006-03-23 02:59:59 -080049static struct swap_info_struct swap_info[MAX_SWAPFILES];
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
Ingo Molnarfc0abb12006-01-18 17:42:33 -080051static DEFINE_MUTEX(swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53/*
54 * We need this because the bdev->unplug_fn can sleep and we cannot
Hugh Dickins5d337b92005-09-03 15:54:41 -070055 * hold swap_lock while calling the unplug_fn. And swap_lock
Ingo Molnarfc0abb12006-01-18 17:42:33 -080056 * cannot be turned into a mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 */
58static DECLARE_RWSEM(swap_unplug_sem);
59
Linus Torvalds1da177e2005-04-16 15:20:36 -070060void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page)
61{
62 swp_entry_t entry;
63
64 down_read(&swap_unplug_sem);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070065 entry.val = page_private(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 if (PageSwapCache(page)) {
67 struct block_device *bdev = swap_info[swp_type(entry)].bdev;
68 struct backing_dev_info *bdi;
69
70 /*
71 * If the page is removed from swapcache from under us (with a
72 * racy try_to_unuse/swapoff) we need an additional reference
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070073 * count to avoid reading garbage from page_private(page) above.
74 * If the WARN_ON triggers during a swapoff it maybe the race
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 * condition and it's harmless. However if it triggers without
76 * swapoff it signals a problem.
77 */
78 WARN_ON(page_count(page) <= 1);
79
80 bdi = bdev->bd_inode->i_mapping->backing_dev_info;
McMullan, Jasonba323112005-05-16 21:53:40 -070081 blk_run_backing_dev(bdi, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 }
83 up_read(&swap_unplug_sem);
84}
85
Hugh Dickins048c27f2005-09-03 15:54:40 -070086#define SWAPFILE_CLUSTER 256
87#define LATENCY_LIMIT 256
88
Hugh Dickins6eb396d2005-09-03 15:54:35 -070089static inline unsigned long scan_swap_map(struct swap_info_struct *si)
Linus Torvalds1da177e2005-04-16 15:20:36 -070090{
Hugh Dickins7dfad412005-09-03 15:54:38 -070091 unsigned long offset, last_in_cluster;
Hugh Dickins048c27f2005-09-03 15:54:40 -070092 int latency_ration = LATENCY_LIMIT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070093
Hugh Dickins7dfad412005-09-03 15:54:38 -070094 /*
95 * We try to cluster swap pages by allocating them sequentially
96 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this
97 * way, however, we resort to first-free allocation, starting
98 * a new cluster. This prevents us from scattering swap pages
99 * all over the entire swap partition, so that we reduce
100 * overall disk seek times between swap pages. -- sct
101 * But we do now try to find an empty cluster. -Andrea
102 */
103
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700104 si->flags += SWP_SCANNING;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700105 if (unlikely(!si->cluster_nr)) {
106 si->cluster_nr = SWAPFILE_CLUSTER - 1;
107 if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER)
108 goto lowest;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700109 spin_unlock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700110
111 offset = si->lowest_bit;
112 last_in_cluster = offset + SWAPFILE_CLUSTER - 1;
113
114 /* Locate the first empty (unaligned) cluster */
115 for (; last_in_cluster <= si->highest_bit; offset++) {
116 if (si->swap_map[offset])
117 last_in_cluster = offset + SWAPFILE_CLUSTER;
118 else if (offset == last_in_cluster) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700119 spin_lock(&swap_lock);
Akinobu Mita9b65ef52006-03-22 00:09:09 -0800120 si->cluster_next = offset-SWAPFILE_CLUSTER+1;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700121 goto cluster;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 }
Hugh Dickins048c27f2005-09-03 15:54:40 -0700123 if (unlikely(--latency_ration < 0)) {
124 cond_resched();
125 latency_ration = LATENCY_LIMIT;
126 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700127 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700128 spin_lock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700129 goto lowest;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700131
132 si->cluster_nr--;
133cluster:
134 offset = si->cluster_next;
135 if (offset > si->highest_bit)
136lowest: offset = si->lowest_bit;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700137checks: if (!(si->flags & SWP_WRITEOK))
138 goto no_page;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700139 if (!si->highest_bit)
140 goto no_page;
141 if (!si->swap_map[offset]) {
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700142 if (offset == si->lowest_bit)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 si->lowest_bit++;
144 if (offset == si->highest_bit)
145 si->highest_bit--;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700146 si->inuse_pages++;
147 if (si->inuse_pages == si->pages) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148 si->lowest_bit = si->max;
149 si->highest_bit = 0;
150 }
151 si->swap_map[offset] = 1;
Hugh Dickins7dfad412005-09-03 15:54:38 -0700152 si->cluster_next = offset + 1;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700153 si->flags -= SWP_SCANNING;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 return offset;
155 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700156
Hugh Dickins5d337b92005-09-03 15:54:41 -0700157 spin_unlock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700158 while (++offset <= si->highest_bit) {
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700159 if (!si->swap_map[offset]) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700160 spin_lock(&swap_lock);
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700161 goto checks;
162 }
Hugh Dickins048c27f2005-09-03 15:54:40 -0700163 if (unlikely(--latency_ration < 0)) {
164 cond_resched();
165 latency_ration = LATENCY_LIMIT;
166 }
Hugh Dickins7dfad412005-09-03 15:54:38 -0700167 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700168 spin_lock(&swap_lock);
Hugh Dickins7dfad412005-09-03 15:54:38 -0700169 goto lowest;
170
171no_page:
Hugh Dickins52b7efdb2005-09-03 15:54:39 -0700172 si->flags -= SWP_SCANNING;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 return 0;
174}
175
176swp_entry_t get_swap_page(void)
177{
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700178 struct swap_info_struct *si;
179 pgoff_t offset;
180 int type, next;
181 int wrapped = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182
Hugh Dickins5d337b92005-09-03 15:54:41 -0700183 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 if (nr_swap_pages <= 0)
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700185 goto noswap;
186 nr_swap_pages--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700188 for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) {
189 si = swap_info + type;
190 next = si->next;
191 if (next < 0 ||
192 (!wrapped && si->prio != swap_info[next].prio)) {
193 next = swap_list.head;
194 wrapped++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 }
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700196
197 if (!si->highest_bit)
198 continue;
199 if (!(si->flags & SWP_WRITEOK))
200 continue;
201
202 swap_list.next = next;
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700203 offset = scan_swap_map(si);
Hugh Dickins5d337b92005-09-03 15:54:41 -0700204 if (offset) {
205 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700206 return swp_entry(type, offset);
Hugh Dickins5d337b92005-09-03 15:54:41 -0700207 }
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700208 next = swap_list.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 }
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700210
211 nr_swap_pages++;
212noswap:
Hugh Dickins5d337b92005-09-03 15:54:41 -0700213 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -0700214 return (swp_entry_t) {0};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215}
216
Rafael J. Wysocki3a291a22006-01-06 00:16:37 -0800217swp_entry_t get_swap_page_of_type(int type)
218{
219 struct swap_info_struct *si;
220 pgoff_t offset;
221
222 spin_lock(&swap_lock);
223 si = swap_info + type;
224 if (si->flags & SWP_WRITEOK) {
225 nr_swap_pages--;
226 offset = scan_swap_map(si);
227 if (offset) {
228 spin_unlock(&swap_lock);
229 return swp_entry(type, offset);
230 }
231 nr_swap_pages++;
232 }
233 spin_unlock(&swap_lock);
234 return (swp_entry_t) {0};
235}
236
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237static struct swap_info_struct * swap_info_get(swp_entry_t entry)
238{
239 struct swap_info_struct * p;
240 unsigned long offset, type;
241
242 if (!entry.val)
243 goto out;
244 type = swp_type(entry);
245 if (type >= nr_swapfiles)
246 goto bad_nofile;
247 p = & swap_info[type];
248 if (!(p->flags & SWP_USED))
249 goto bad_device;
250 offset = swp_offset(entry);
251 if (offset >= p->max)
252 goto bad_offset;
253 if (!p->swap_map[offset])
254 goto bad_free;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700255 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 return p;
257
258bad_free:
259 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val);
260 goto out;
261bad_offset:
262 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val);
263 goto out;
264bad_device:
265 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val);
266 goto out;
267bad_nofile:
268 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val);
269out:
270 return NULL;
271}
272
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273static int swap_entry_free(struct swap_info_struct *p, unsigned long offset)
274{
275 int count = p->swap_map[offset];
276
277 if (count < SWAP_MAP_MAX) {
278 count--;
279 p->swap_map[offset] = count;
280 if (!count) {
281 if (offset < p->lowest_bit)
282 p->lowest_bit = offset;
283 if (offset > p->highest_bit)
284 p->highest_bit = offset;
Hugh Dickins89d09a22005-09-03 15:54:36 -0700285 if (p->prio > swap_info[swap_list.next].prio)
286 swap_list.next = p - swap_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 nr_swap_pages++;
288 p->inuse_pages--;
289 }
290 }
291 return count;
292}
293
294/*
295 * Caller has made sure that the swapdevice corresponding to entry
296 * is still around or has not been recycled.
297 */
298void swap_free(swp_entry_t entry)
299{
300 struct swap_info_struct * p;
301
302 p = swap_info_get(entry);
303 if (p) {
304 swap_entry_free(p, swp_offset(entry));
Hugh Dickins5d337b92005-09-03 15:54:41 -0700305 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 }
307}
308
309/*
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700310 * How many references to page are currently swapped out?
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 */
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700312static inline int page_swapcount(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313{
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700314 int count = 0;
315 struct swap_info_struct *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 swp_entry_t entry;
317
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700318 entry.val = page_private(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 p = swap_info_get(entry);
320 if (p) {
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700321 /* Subtract the 1 for the swap cache itself */
322 count = p->swap_map[swp_offset(entry)] - 1;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700323 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 }
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700325 return count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326}
327
328/*
329 * We can use this swap cache entry directly
330 * if there are no other references to it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 */
332int can_share_swap_page(struct page *page)
333{
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700334 int count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700336 BUG_ON(!PageLocked(page));
337 count = page_mapcount(page);
338 if (count <= 1 && PageSwapCache(page))
339 count += page_swapcount(page);
340 return count == 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341}
342
343/*
344 * Work out if there are any other processes sharing this
345 * swap cache page. Free it if you can. Return success.
346 */
347int remove_exclusive_swap_page(struct page *page)
348{
349 int retval;
350 struct swap_info_struct * p;
351 swp_entry_t entry;
352
353 BUG_ON(PagePrivate(page));
354 BUG_ON(!PageLocked(page));
355
356 if (!PageSwapCache(page))
357 return 0;
358 if (PageWriteback(page))
359 return 0;
360 if (page_count(page) != 2) /* 2: us + cache */
361 return 0;
362
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700363 entry.val = page_private(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 p = swap_info_get(entry);
365 if (!p)
366 return 0;
367
368 /* Is the only swap cache user the cache itself? */
369 retval = 0;
370 if (p->swap_map[swp_offset(entry)] == 1) {
371 /* Recheck the page count with the swapcache lock held.. */
Nick Piggin19fd6232008-07-25 19:45:32 -0700372 spin_lock_irq(&swapper_space.tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 if ((page_count(page) == 2) && !PageWriteback(page)) {
374 __delete_from_swap_cache(page);
375 SetPageDirty(page);
376 retval = 1;
377 }
Nick Piggin19fd6232008-07-25 19:45:32 -0700378 spin_unlock_irq(&swapper_space.tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700380 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381
382 if (retval) {
383 swap_free(entry);
384 page_cache_release(page);
385 }
386
387 return retval;
388}
389
390/*
391 * Free the swap entry like above, but also try to
392 * free the page cache entry if it is the last user.
393 */
394void free_swap_and_cache(swp_entry_t entry)
395{
396 struct swap_info_struct * p;
397 struct page *page = NULL;
398
Christoph Lameter06972122006-06-23 02:03:35 -0700399 if (is_migration_entry(entry))
400 return;
401
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 p = swap_info_get(entry);
403 if (p) {
Nick Piggin93fac702006-03-31 02:29:56 -0800404 if (swap_entry_free(p, swp_offset(entry)) == 1) {
405 page = find_get_page(&swapper_space, entry.val);
Nick Piggin529ae9a2008-08-02 12:01:03 +0200406 if (page && unlikely(!trylock_page(page))) {
Nick Piggin93fac702006-03-31 02:29:56 -0800407 page_cache_release(page);
408 page = NULL;
409 }
410 }
Hugh Dickins5d337b92005-09-03 15:54:41 -0700411 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 }
413 if (page) {
414 int one_user;
415
416 BUG_ON(PagePrivate(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 one_user = (page_count(page) == 2);
418 /* Only cache user (+us), or swap space full? Free it! */
Nick Piggin93fac702006-03-31 02:29:56 -0800419 /* Also recheck PageSwapCache after page is locked (above) */
420 if (PageSwapCache(page) && !PageWriteback(page) &&
421 (one_user || vm_swap_full())) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 delete_from_swap_cache(page);
423 SetPageDirty(page);
424 }
425 unlock_page(page);
426 page_cache_release(page);
427 }
428}
429
Rafael J. Wysockib0cb1a12007-07-29 23:24:36 +0200430#ifdef CONFIG_HIBERNATION
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800431/*
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800432 * Find the swap type that corresponds to given device (if any).
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800433 *
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800434 * @offset - number of the PAGE_SIZE-sized block of the device, starting
435 * from 0, in which the swap header is expected to be located.
436 *
437 * This is needed for the suspend to disk (aka swsusp).
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800438 */
Rafael J. Wysocki7bf23682007-01-05 16:36:28 -0800439int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800440{
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800441 struct block_device *bdev = NULL;
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800442 int i;
443
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800444 if (device)
445 bdev = bdget(device);
446
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800447 spin_lock(&swap_lock);
448 for (i = 0; i < nr_swapfiles; i++) {
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800449 struct swap_info_struct *sis = swap_info + i;
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800450
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800451 if (!(sis->flags & SWP_WRITEOK))
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800452 continue;
Rafael J. Wysockib6b5bce2006-08-27 01:23:25 -0700453
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800454 if (!bdev) {
Rafael J. Wysocki7bf23682007-01-05 16:36:28 -0800455 if (bdev_p)
456 *bdev_p = sis->bdev;
457
Rafael J. Wysocki6e1819d2006-03-23 03:00:03 -0800458 spin_unlock(&swap_lock);
459 return i;
460 }
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800461 if (bdev == sis->bdev) {
462 struct swap_extent *se;
463
464 se = list_entry(sis->extent_list.next,
465 struct swap_extent, list);
466 if (se->start_block == offset) {
Rafael J. Wysocki7bf23682007-01-05 16:36:28 -0800467 if (bdev_p)
468 *bdev_p = sis->bdev;
469
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800470 spin_unlock(&swap_lock);
471 bdput(bdev);
472 return i;
473 }
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800474 }
475 }
476 spin_unlock(&swap_lock);
Rafael J. Wysocki915bae92006-12-06 20:34:07 -0800477 if (bdev)
478 bdput(bdev);
479
Rafael J. Wysockif577eb32006-03-23 02:59:59 -0800480 return -ENODEV;
481}
482
483/*
484 * Return either the total number of swap pages of given type, or the number
485 * of free pages of that type (depending on @free)
486 *
487 * This is needed for software suspend
488 */
489unsigned int count_swap_pages(int type, int free)
490{
491 unsigned int n = 0;
492
493 if (type < nr_swapfiles) {
494 spin_lock(&swap_lock);
495 if (swap_info[type].flags & SWP_WRITEOK) {
496 n = swap_info[type].pages;
497 if (free)
498 n -= swap_info[type].inuse_pages;
499 }
500 spin_unlock(&swap_lock);
501 }
502 return n;
503}
504#endif
505
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506/*
Hugh Dickins72866f62005-10-29 18:15:55 -0700507 * No need to decide whether this PTE shares the swap entry with others,
508 * just let do_wp_page work it out if a write is requested later - to
509 * force COW, vm_page_prot omits write permission from any private vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 */
Hugh Dickins044d66c2008-02-07 00:14:04 -0800511static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 unsigned long addr, swp_entry_t entry, struct page *page)
513{
Hugh Dickins044d66c2008-02-07 00:14:04 -0800514 spinlock_t *ptl;
515 pte_t *pte;
516 int ret = 1;
517
Balbir Singhe1a1cd52008-02-07 00:14:02 -0800518 if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL))
Hugh Dickins044d66c2008-02-07 00:14:04 -0800519 ret = -ENOMEM;
520
521 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
522 if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) {
523 if (ret > 0)
524 mem_cgroup_uncharge_page(page);
525 ret = 0;
526 goto out;
527 }
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800528
Hugh Dickins42946212005-10-29 18:16:05 -0700529 inc_mm_counter(vma->vm_mm, anon_rss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 get_page(page);
531 set_pte_at(vma->vm_mm, addr, pte,
532 pte_mkold(mk_pte(page, vma->vm_page_prot)));
533 page_add_anon_rmap(page, vma, addr);
534 swap_free(entry);
535 /*
536 * Move the page to the active list so it is not
537 * immediately swapped out again after swapon.
538 */
539 activate_page(page);
Hugh Dickins044d66c2008-02-07 00:14:04 -0800540out:
541 pte_unmap_unlock(pte, ptl);
542 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543}
544
545static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
546 unsigned long addr, unsigned long end,
547 swp_entry_t entry, struct page *page)
548{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 pte_t swp_pte = swp_entry_to_pte(entry);
Hugh Dickins705e87c2005-10-29 18:16:27 -0700550 pte_t *pte;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800551 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552
Hugh Dickins044d66c2008-02-07 00:14:04 -0800553 /*
554 * We don't actually need pte lock while scanning for swp_pte: since
555 * we hold page lock and mmap_sem, swp_pte cannot be inserted into the
556 * page table while we're scanning; though it could get zapped, and on
557 * some architectures (e.g. x86_32 with PAE) we might catch a glimpse
558 * of unmatched parts which look like swp_pte, so unuse_pte must
559 * recheck under pte lock. Scanning without pte lock lets it be
560 * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE.
561 */
562 pte = pte_offset_map(pmd, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 do {
564 /*
565 * swapoff spends a _lot_ of time in this loop!
566 * Test inline before going to call unuse_pte.
567 */
568 if (unlikely(pte_same(*pte, swp_pte))) {
Hugh Dickins044d66c2008-02-07 00:14:04 -0800569 pte_unmap(pte);
570 ret = unuse_pte(vma, pmd, addr, entry, page);
571 if (ret)
572 goto out;
573 pte = pte_offset_map(pmd, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 }
575 } while (pte++, addr += PAGE_SIZE, addr != end);
Hugh Dickins044d66c2008-02-07 00:14:04 -0800576 pte_unmap(pte - 1);
577out:
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800578 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579}
580
581static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
582 unsigned long addr, unsigned long end,
583 swp_entry_t entry, struct page *page)
584{
585 pmd_t *pmd;
586 unsigned long next;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800587 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588
589 pmd = pmd_offset(pud, addr);
590 do {
591 next = pmd_addr_end(addr, end);
592 if (pmd_none_or_clear_bad(pmd))
593 continue;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800594 ret = unuse_pte_range(vma, pmd, addr, next, entry, page);
595 if (ret)
596 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 } while (pmd++, addr = next, addr != end);
598 return 0;
599}
600
601static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
602 unsigned long addr, unsigned long end,
603 swp_entry_t entry, struct page *page)
604{
605 pud_t *pud;
606 unsigned long next;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800607 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608
609 pud = pud_offset(pgd, addr);
610 do {
611 next = pud_addr_end(addr, end);
612 if (pud_none_or_clear_bad(pud))
613 continue;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800614 ret = unuse_pmd_range(vma, pud, addr, next, entry, page);
615 if (ret)
616 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 } while (pud++, addr = next, addr != end);
618 return 0;
619}
620
621static int unuse_vma(struct vm_area_struct *vma,
622 swp_entry_t entry, struct page *page)
623{
624 pgd_t *pgd;
625 unsigned long addr, end, next;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800626 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627
628 if (page->mapping) {
629 addr = page_address_in_vma(page, vma);
630 if (addr == -EFAULT)
631 return 0;
632 else
633 end = addr + PAGE_SIZE;
634 } else {
635 addr = vma->vm_start;
636 end = vma->vm_end;
637 }
638
639 pgd = pgd_offset(vma->vm_mm, addr);
640 do {
641 next = pgd_addr_end(addr, end);
642 if (pgd_none_or_clear_bad(pgd))
643 continue;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800644 ret = unuse_pud_range(vma, pgd, addr, next, entry, page);
645 if (ret)
646 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 } while (pgd++, addr = next, addr != end);
648 return 0;
649}
650
651static int unuse_mm(struct mm_struct *mm,
652 swp_entry_t entry, struct page *page)
653{
654 struct vm_area_struct *vma;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800655 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656
657 if (!down_read_trylock(&mm->mmap_sem)) {
658 /*
Fernando Luis Vazquez Cao7d034312008-07-29 22:33:41 -0700659 * Activate page so shrink_inactive_list is unlikely to unmap
660 * its ptes while lock is dropped, so swapoff can make progress.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661 */
Hugh Dickinsc475a8a2005-06-21 17:15:12 -0700662 activate_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663 unlock_page(page);
664 down_read(&mm->mmap_sem);
665 lock_page(page);
666 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667 for (vma = mm->mmap; vma; vma = vma->vm_next) {
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800668 if (vma->anon_vma && (ret = unuse_vma(vma, entry, page)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669 break;
670 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 up_read(&mm->mmap_sem);
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800672 return (ret < 0)? ret: 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673}
674
675/*
676 * Scan swap_map from current position to next entry still in use.
677 * Recycle to start on reaching the end, returning 0 when empty.
678 */
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700679static unsigned int find_next_to_unuse(struct swap_info_struct *si,
680 unsigned int prev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681{
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700682 unsigned int max = si->max;
683 unsigned int i = prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684 int count;
685
686 /*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700687 * No need for swap_lock here: we're just looking
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688 * for whether an entry is in use, not modifying it; false
689 * hits are okay, and sys_swapoff() has already prevented new
Hugh Dickins5d337b92005-09-03 15:54:41 -0700690 * allocations from this area (while holding swap_lock).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700691 */
692 for (;;) {
693 if (++i >= max) {
694 if (!prev) {
695 i = 0;
696 break;
697 }
698 /*
699 * No entries in use at top of swap_map,
700 * loop back to start and recheck there.
701 */
702 max = prev + 1;
703 prev = 0;
704 i = 1;
705 }
706 count = si->swap_map[i];
707 if (count && count != SWAP_MAP_BAD)
708 break;
709 }
710 return i;
711}
712
713/*
714 * We completely avoid races by reading each swap page in advance,
715 * and then search for the process using it. All the necessary
716 * page table adjustments can then be made atomically.
717 */
718static int try_to_unuse(unsigned int type)
719{
720 struct swap_info_struct * si = &swap_info[type];
721 struct mm_struct *start_mm;
722 unsigned short *swap_map;
723 unsigned short swcount;
724 struct page *page;
725 swp_entry_t entry;
Hugh Dickins6eb396d2005-09-03 15:54:35 -0700726 unsigned int i = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727 int retval = 0;
728 int reset_overflow = 0;
729 int shmem;
730
731 /*
732 * When searching mms for an entry, a good strategy is to
733 * start at the first mm we freed the previous entry from
734 * (though actually we don't notice whether we or coincidence
735 * freed the entry). Initialize this start_mm with a hold.
736 *
737 * A simpler strategy would be to start at the last mm we
738 * freed the previous entry from; but that would take less
739 * advantage of mmlist ordering, which clusters forked mms
740 * together, child after parent. If we race with dup_mmap(), we
741 * prefer to resolve parent before child, lest we miss entries
742 * duplicated after we scanned child: using last mm would invert
743 * that. Though it's only a serious concern when an overflowed
744 * swap count is reset from SWAP_MAP_MAX, preventing a rescan.
745 */
746 start_mm = &init_mm;
747 atomic_inc(&init_mm.mm_users);
748
749 /*
750 * Keep on scanning until all entries have gone. Usually,
751 * one pass through swap_map is enough, but not necessarily:
752 * there are races when an instance of an entry might be missed.
753 */
754 while ((i = find_next_to_unuse(si, i)) != 0) {
755 if (signal_pending(current)) {
756 retval = -EINTR;
757 break;
758 }
759
760 /*
761 * Get a page for the entry, using the existing swap
762 * cache page if there is one. Otherwise, get a clean
763 * page and read the swap into it.
764 */
765 swap_map = &si->swap_map[i];
766 entry = swp_entry(type, i);
Hugh Dickins02098fe2008-02-04 22:28:42 -0800767 page = read_swap_cache_async(entry,
768 GFP_HIGHUSER_MOVABLE, NULL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 if (!page) {
770 /*
771 * Either swap_duplicate() failed because entry
772 * has been freed independently, and will not be
773 * reused since sys_swapoff() already disabled
774 * allocation from here, or alloc_page() failed.
775 */
776 if (!*swap_map)
777 continue;
778 retval = -ENOMEM;
779 break;
780 }
781
782 /*
783 * Don't hold on to start_mm if it looks like exiting.
784 */
785 if (atomic_read(&start_mm->mm_users) == 1) {
786 mmput(start_mm);
787 start_mm = &init_mm;
788 atomic_inc(&init_mm.mm_users);
789 }
790
791 /*
792 * Wait for and lock page. When do_swap_page races with
793 * try_to_unuse, do_swap_page can handle the fault much
794 * faster than try_to_unuse can locate the entry. This
795 * apparently redundant "wait_on_page_locked" lets try_to_unuse
796 * defer to do_swap_page in such a case - in some tests,
797 * do_swap_page and try_to_unuse repeatedly compete.
798 */
799 wait_on_page_locked(page);
800 wait_on_page_writeback(page);
801 lock_page(page);
802 wait_on_page_writeback(page);
803
804 /*
805 * Remove all references to entry.
806 * Whenever we reach init_mm, there's no address space
807 * to search, but use it as a reminder to search shmem.
808 */
809 shmem = 0;
810 swcount = *swap_map;
811 if (swcount > 1) {
812 if (start_mm == &init_mm)
813 shmem = shmem_unuse(entry, page);
814 else
815 retval = unuse_mm(start_mm, entry, page);
816 }
817 if (*swap_map > 1) {
818 int set_start_mm = (*swap_map >= swcount);
819 struct list_head *p = &start_mm->mmlist;
820 struct mm_struct *new_start_mm = start_mm;
821 struct mm_struct *prev_mm = start_mm;
822 struct mm_struct *mm;
823
824 atomic_inc(&new_start_mm->mm_users);
825 atomic_inc(&prev_mm->mm_users);
826 spin_lock(&mmlist_lock);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800827 while (*swap_map > 1 && !retval && !shmem &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828 (p = p->next) != &start_mm->mmlist) {
829 mm = list_entry(p, struct mm_struct, mmlist);
Hugh Dickins70af7c52006-06-23 02:03:44 -0700830 if (!atomic_inc_not_zero(&mm->mm_users))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 spin_unlock(&mmlist_lock);
833 mmput(prev_mm);
834 prev_mm = mm;
835
836 cond_resched();
837
838 swcount = *swap_map;
839 if (swcount <= 1)
840 ;
841 else if (mm == &init_mm) {
842 set_start_mm = 1;
843 shmem = shmem_unuse(entry, page);
844 } else
845 retval = unuse_mm(mm, entry, page);
846 if (set_start_mm && *swap_map < swcount) {
847 mmput(new_start_mm);
848 atomic_inc(&mm->mm_users);
849 new_start_mm = mm;
850 set_start_mm = 0;
851 }
852 spin_lock(&mmlist_lock);
853 }
854 spin_unlock(&mmlist_lock);
855 mmput(prev_mm);
856 mmput(start_mm);
857 start_mm = new_start_mm;
858 }
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800859 if (shmem) {
860 /* page has already been unlocked and released */
861 if (shmem > 0)
862 continue;
863 retval = shmem;
864 break;
865 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866 if (retval) {
867 unlock_page(page);
868 page_cache_release(page);
869 break;
870 }
871
872 /*
873 * How could swap count reach 0x7fff when the maximum
874 * pid is 0x7fff, and there's no way to repeat a swap
875 * page within an mm (except in shmem, where it's the
876 * shared object which takes the reference count)?
877 * We believe SWAP_MAP_MAX cannot occur in Linux 2.4.
878 *
879 * If that's wrong, then we should worry more about
880 * exit_mmap() and do_munmap() cases described above:
881 * we might be resetting SWAP_MAP_MAX too early here.
882 * We know "Undead"s can happen, they're okay, so don't
883 * report them; but do report if we reset SWAP_MAP_MAX.
884 */
885 if (*swap_map == SWAP_MAP_MAX) {
Hugh Dickins5d337b92005-09-03 15:54:41 -0700886 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887 *swap_map = 1;
Hugh Dickins5d337b92005-09-03 15:54:41 -0700888 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889 reset_overflow = 1;
890 }
891
892 /*
893 * If a reference remains (rare), we would like to leave
894 * the page in the swap cache; but try_to_unmap could
895 * then re-duplicate the entry once we drop page lock,
896 * so we might loop indefinitely; also, that page could
897 * not be swapped out to other storage meanwhile. So:
898 * delete from cache even if there's another reference,
899 * after ensuring that the data has been saved to disk -
900 * since if the reference remains (rarer), it will be
901 * read from disk into another page. Splitting into two
902 * pages would be incorrect if swap supported "shared
903 * private" pages, but they are handled by tmpfs files.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 */
905 if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) {
906 struct writeback_control wbc = {
907 .sync_mode = WB_SYNC_NONE,
908 };
909
910 swap_writepage(page, &wbc);
911 lock_page(page);
912 wait_on_page_writeback(page);
913 }
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800914 if (PageSwapCache(page))
915 delete_from_swap_cache(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916
917 /*
918 * So we could skip searching mms once swap count went
919 * to 1, we did not mark any present ptes as dirty: must
Anderson Briglia2706a1b2007-07-15 23:38:09 -0700920 * mark page dirty so shrink_page_list will preserve it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921 */
922 SetPageDirty(page);
923 unlock_page(page);
924 page_cache_release(page);
925
926 /*
927 * Make sure that we aren't completely killing
928 * interactive performance.
929 */
930 cond_resched();
931 }
932
933 mmput(start_mm);
934 if (reset_overflow) {
935 printk(KERN_WARNING "swapoff: cleared swap entry overflow\n");
936 swap_overflow = 0;
937 }
938 return retval;
939}
940
941/*
Hugh Dickins5d337b92005-09-03 15:54:41 -0700942 * After a successful try_to_unuse, if no swap is now in use, we know
943 * we can empty the mmlist. swap_lock must be held on entry and exit.
944 * Note that mmlist_lock nests inside swap_lock, and an mm must be
Linus Torvalds1da177e2005-04-16 15:20:36 -0700945 * added to the mmlist just after page_duplicate - before would be racy.
946 */
947static void drain_mmlist(void)
948{
949 struct list_head *p, *next;
950 unsigned int i;
951
952 for (i = 0; i < nr_swapfiles; i++)
953 if (swap_info[i].inuse_pages)
954 return;
955 spin_lock(&mmlist_lock);
956 list_for_each_safe(p, next, &init_mm.mmlist)
957 list_del_init(p);
958 spin_unlock(&mmlist_lock);
959}
960
961/*
962 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
963 * corresponds to page offset `offset'.
964 */
965sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset)
966{
967 struct swap_extent *se = sis->curr_swap_extent;
968 struct swap_extent *start_se = se;
969
970 for ( ; ; ) {
971 struct list_head *lh;
972
973 if (se->start_page <= offset &&
974 offset < (se->start_page + se->nr_pages)) {
975 return se->start_block + (offset - se->start_page);
976 }
Hugh Dickins11d31882005-09-03 15:54:34 -0700977 lh = se->list.next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700978 if (lh == &sis->extent_list)
Hugh Dickins11d31882005-09-03 15:54:34 -0700979 lh = lh->next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 se = list_entry(lh, struct swap_extent, list);
981 sis->curr_swap_extent = se;
982 BUG_ON(se == start_se); /* It *must* be present */
983 }
984}
985
Rafael J. Wysockib0cb1a12007-07-29 23:24:36 +0200986#ifdef CONFIG_HIBERNATION
Rafael J. Wysocki3aef83e2006-12-06 20:34:10 -0800987/*
988 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
989 * corresponding to given index in swap_info (swap type).
990 */
991sector_t swapdev_block(int swap_type, pgoff_t offset)
992{
993 struct swap_info_struct *sis;
994
995 if (swap_type >= nr_swapfiles)
996 return 0;
997
998 sis = swap_info + swap_type;
999 return (sis->flags & SWP_WRITEOK) ? map_swap_page(sis, offset) : 0;
1000}
Rafael J. Wysockib0cb1a12007-07-29 23:24:36 +02001001#endif /* CONFIG_HIBERNATION */
Rafael J. Wysocki3aef83e2006-12-06 20:34:10 -08001002
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003/*
1004 * Free all of a swapdev's extent information
1005 */
1006static void destroy_swap_extents(struct swap_info_struct *sis)
1007{
1008 while (!list_empty(&sis->extent_list)) {
1009 struct swap_extent *se;
1010
1011 se = list_entry(sis->extent_list.next,
1012 struct swap_extent, list);
1013 list_del(&se->list);
1014 kfree(se);
1015 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001016}
1017
1018/*
1019 * Add a block range (and the corresponding page range) into this swapdev's
Hugh Dickins11d31882005-09-03 15:54:34 -07001020 * extent list. The extent list is kept sorted in page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001021 *
Hugh Dickins11d31882005-09-03 15:54:34 -07001022 * This function rather assumes that it is called in ascending page order.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001023 */
1024static int
1025add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
1026 unsigned long nr_pages, sector_t start_block)
1027{
1028 struct swap_extent *se;
1029 struct swap_extent *new_se;
1030 struct list_head *lh;
1031
Hugh Dickins11d31882005-09-03 15:54:34 -07001032 lh = sis->extent_list.prev; /* The highest page extent */
1033 if (lh != &sis->extent_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001034 se = list_entry(lh, struct swap_extent, list);
Hugh Dickins11d31882005-09-03 15:54:34 -07001035 BUG_ON(se->start_page + se->nr_pages != start_page);
1036 if (se->start_block + se->nr_pages == start_block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037 /* Merge it */
1038 se->nr_pages += nr_pages;
1039 return 0;
1040 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041 }
1042
1043 /*
1044 * No merge. Insert a new extent, preserving ordering.
1045 */
1046 new_se = kmalloc(sizeof(*se), GFP_KERNEL);
1047 if (new_se == NULL)
1048 return -ENOMEM;
1049 new_se->start_page = start_page;
1050 new_se->nr_pages = nr_pages;
1051 new_se->start_block = start_block;
1052
Hugh Dickins11d31882005-09-03 15:54:34 -07001053 list_add_tail(&new_se->list, &sis->extent_list);
Hugh Dickins53092a72005-09-03 15:54:34 -07001054 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055}
1056
1057/*
1058 * A `swap extent' is a simple thing which maps a contiguous range of pages
1059 * onto a contiguous range of disk blocks. An ordered list of swap extents
1060 * is built at swapon time and is then used at swap_writepage/swap_readpage
1061 * time for locating where on disk a page belongs.
1062 *
1063 * If the swapfile is an S_ISBLK block device, a single extent is installed.
1064 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
1065 * swap files identically.
1066 *
1067 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
1068 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
1069 * swapfiles are handled *identically* after swapon time.
1070 *
1071 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
1072 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
1073 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
1074 * requirements, they are simply tossed out - we will never use those blocks
1075 * for swapping.
1076 *
Hugh Dickinsb0d9bcd2005-09-03 15:54:31 -07001077 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
1079 * which will scribble on the fs.
1080 *
1081 * The amount of disk space which a single swap extent represents varies.
1082 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
1083 * extents in the list. To avoid much list walking, we cache the previous
1084 * search location in `curr_swap_extent', and start new searches from there.
1085 * This is extremely effective. The average number of iterations in
1086 * map_swap_page() has been measured at about 0.3 per page. - akpm.
1087 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001088static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089{
1090 struct inode *inode;
1091 unsigned blocks_per_page;
1092 unsigned long page_no;
1093 unsigned blkbits;
1094 sector_t probe_block;
1095 sector_t last_block;
Hugh Dickins53092a72005-09-03 15:54:34 -07001096 sector_t lowest_block = -1;
1097 sector_t highest_block = 0;
1098 int nr_extents = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099 int ret;
1100
1101 inode = sis->swap_file->f_mapping->host;
1102 if (S_ISBLK(inode->i_mode)) {
1103 ret = add_swap_extent(sis, 0, sis->max, 0);
Hugh Dickins53092a72005-09-03 15:54:34 -07001104 *span = sis->pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105 goto done;
1106 }
1107
1108 blkbits = inode->i_blkbits;
1109 blocks_per_page = PAGE_SIZE >> blkbits;
1110
1111 /*
1112 * Map all the blocks into the extent list. This code doesn't try
1113 * to be very smart.
1114 */
1115 probe_block = 0;
1116 page_no = 0;
1117 last_block = i_size_read(inode) >> blkbits;
1118 while ((probe_block + blocks_per_page) <= last_block &&
1119 page_no < sis->max) {
1120 unsigned block_in_page;
1121 sector_t first_block;
1122
1123 first_block = bmap(inode, probe_block);
1124 if (first_block == 0)
1125 goto bad_bmap;
1126
1127 /*
1128 * It must be PAGE_SIZE aligned on-disk
1129 */
1130 if (first_block & (blocks_per_page - 1)) {
1131 probe_block++;
1132 goto reprobe;
1133 }
1134
1135 for (block_in_page = 1; block_in_page < blocks_per_page;
1136 block_in_page++) {
1137 sector_t block;
1138
1139 block = bmap(inode, probe_block + block_in_page);
1140 if (block == 0)
1141 goto bad_bmap;
1142 if (block != first_block + block_in_page) {
1143 /* Discontiguity */
1144 probe_block++;
1145 goto reprobe;
1146 }
1147 }
1148
Hugh Dickins53092a72005-09-03 15:54:34 -07001149 first_block >>= (PAGE_SHIFT - blkbits);
1150 if (page_no) { /* exclude the header page */
1151 if (first_block < lowest_block)
1152 lowest_block = first_block;
1153 if (first_block > highest_block)
1154 highest_block = first_block;
1155 }
1156
Linus Torvalds1da177e2005-04-16 15:20:36 -07001157 /*
1158 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1159 */
Hugh Dickins53092a72005-09-03 15:54:34 -07001160 ret = add_swap_extent(sis, page_no, 1, first_block);
1161 if (ret < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 goto out;
Hugh Dickins53092a72005-09-03 15:54:34 -07001163 nr_extents += ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001164 page_no++;
1165 probe_block += blocks_per_page;
1166reprobe:
1167 continue;
1168 }
Hugh Dickins53092a72005-09-03 15:54:34 -07001169 ret = nr_extents;
1170 *span = 1 + highest_block - lowest_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171 if (page_no == 0)
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001172 page_no = 1; /* force Empty message */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001173 sis->max = page_no;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001174 sis->pages = page_no - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175 sis->highest_bit = page_no - 1;
1176done:
1177 sis->curr_swap_extent = list_entry(sis->extent_list.prev,
1178 struct swap_extent, list);
1179 goto out;
1180bad_bmap:
1181 printk(KERN_ERR "swapon: swapfile has holes\n");
1182 ret = -EINVAL;
1183out:
1184 return ret;
1185}
1186
1187#if 0 /* We don't need this yet */
1188#include <linux/backing-dev.h>
1189int page_queue_congested(struct page *page)
1190{
1191 struct backing_dev_info *bdi;
1192
1193 BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */
1194
1195 if (PageSwapCache(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07001196 swp_entry_t entry = { .val = page_private(page) };
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197 struct swap_info_struct *sis;
1198
1199 sis = get_swap_info_struct(swp_type(entry));
1200 bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info;
1201 } else
1202 bdi = page->mapping->backing_dev_info;
1203 return bdi_write_congested(bdi);
1204}
1205#endif
1206
1207asmlinkage long sys_swapoff(const char __user * specialfile)
1208{
1209 struct swap_info_struct * p = NULL;
1210 unsigned short *swap_map;
1211 struct file *swap_file, *victim;
1212 struct address_space *mapping;
1213 struct inode *inode;
1214 char * pathname;
1215 int i, type, prev;
1216 int err;
1217
1218 if (!capable(CAP_SYS_ADMIN))
1219 return -EPERM;
1220
1221 pathname = getname(specialfile);
1222 err = PTR_ERR(pathname);
1223 if (IS_ERR(pathname))
1224 goto out;
1225
1226 victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0);
1227 putname(pathname);
1228 err = PTR_ERR(victim);
1229 if (IS_ERR(victim))
1230 goto out;
1231
1232 mapping = victim->f_mapping;
1233 prev = -1;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001234 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
1236 p = swap_info + type;
1237 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
1238 if (p->swap_file->f_mapping == mapping)
1239 break;
1240 }
1241 prev = type;
1242 }
1243 if (type < 0) {
1244 err = -EINVAL;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001245 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001246 goto out_dput;
1247 }
1248 if (!security_vm_enough_memory(p->pages))
1249 vm_unacct_memory(p->pages);
1250 else {
1251 err = -ENOMEM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001252 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253 goto out_dput;
1254 }
1255 if (prev < 0) {
1256 swap_list.head = p->next;
1257 } else {
1258 swap_info[prev].next = p->next;
1259 }
1260 if (type == swap_list.next) {
1261 /* just pick something that's safe... */
1262 swap_list.next = swap_list.head;
1263 }
Hugh Dickins78ecba02008-07-23 21:28:23 -07001264 if (p->prio < 0) {
1265 for (i = p->next; i >= 0; i = swap_info[i].next)
1266 swap_info[i].prio = p->prio--;
1267 least_priority++;
1268 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001269 nr_swap_pages -= p->pages;
1270 total_swap_pages -= p->pages;
1271 p->flags &= ~SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001272 spin_unlock(&swap_lock);
Hugh Dickinsfb4f88d2005-09-03 15:54:37 -07001273
Linus Torvalds1da177e2005-04-16 15:20:36 -07001274 current->flags |= PF_SWAPOFF;
1275 err = try_to_unuse(type);
1276 current->flags &= ~PF_SWAPOFF;
1277
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278 if (err) {
1279 /* re-insert swap space back into swap_list */
Hugh Dickins5d337b92005-09-03 15:54:41 -07001280 spin_lock(&swap_lock);
Hugh Dickins78ecba02008-07-23 21:28:23 -07001281 if (p->prio < 0)
1282 p->prio = --least_priority;
1283 prev = -1;
1284 for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285 if (p->prio >= swap_info[i].prio)
1286 break;
Hugh Dickins78ecba02008-07-23 21:28:23 -07001287 prev = i;
1288 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289 p->next = i;
1290 if (prev < 0)
1291 swap_list.head = swap_list.next = p - swap_info;
1292 else
1293 swap_info[prev].next = p - swap_info;
1294 nr_swap_pages += p->pages;
1295 total_swap_pages += p->pages;
1296 p->flags |= SWP_WRITEOK;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001297 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298 goto out_dput;
1299 }
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001300
1301 /* wait for any unplug function to finish */
1302 down_write(&swap_unplug_sem);
1303 up_write(&swap_unplug_sem);
1304
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001305 destroy_swap_extents(p);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001306 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001307 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001308 drain_mmlist();
Hugh Dickins5d337b92005-09-03 15:54:41 -07001309
1310 /* wait for anyone still in scan_swap_map */
1311 p->highest_bit = 0; /* cuts scans short */
1312 while (p->flags >= SWP_SCANNING) {
1313 spin_unlock(&swap_lock);
Nishanth Aravamudan13e4b572005-09-10 00:27:25 -07001314 schedule_timeout_uninterruptible(1);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001315 spin_lock(&swap_lock);
1316 }
1317
Linus Torvalds1da177e2005-04-16 15:20:36 -07001318 swap_file = p->swap_file;
1319 p->swap_file = NULL;
1320 p->max = 0;
1321 swap_map = p->swap_map;
1322 p->swap_map = NULL;
1323 p->flags = 0;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001324 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001325 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001326 vfree(swap_map);
1327 inode = mapping->host;
1328 if (S_ISBLK(inode->i_mode)) {
1329 struct block_device *bdev = I_BDEV(inode);
1330 set_blocksize(bdev, p->old_block_size);
1331 bd_release(bdev);
1332 } else {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001333 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334 inode->i_flags &= ~S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001335 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336 }
1337 filp_close(swap_file, NULL);
1338 err = 0;
1339
1340out_dput:
1341 filp_close(victim, NULL);
1342out:
1343 return err;
1344}
1345
1346#ifdef CONFIG_PROC_FS
1347/* iterator */
1348static void *swap_start(struct seq_file *swap, loff_t *pos)
1349{
1350 struct swap_info_struct *ptr = swap_info;
1351 int i;
1352 loff_t l = *pos;
1353
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001354 mutex_lock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001356 if (!l)
1357 return SEQ_START_TOKEN;
1358
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359 for (i = 0; i < nr_swapfiles; i++, ptr++) {
1360 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1361 continue;
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001362 if (!--l)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363 return ptr;
1364 }
1365
1366 return NULL;
1367}
1368
1369static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
1370{
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001371 struct swap_info_struct *ptr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 struct swap_info_struct *endptr = swap_info + nr_swapfiles;
1373
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001374 if (v == SEQ_START_TOKEN)
1375 ptr = swap_info;
1376 else {
1377 ptr = v;
1378 ptr++;
1379 }
1380
1381 for (; ptr < endptr; ptr++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1383 continue;
1384 ++*pos;
1385 return ptr;
1386 }
1387
1388 return NULL;
1389}
1390
1391static void swap_stop(struct seq_file *swap, void *v)
1392{
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001393 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394}
1395
1396static int swap_show(struct seq_file *swap, void *v)
1397{
1398 struct swap_info_struct *ptr = v;
1399 struct file *file;
1400 int len;
1401
Suleiman Souhlal881e4aa2006-12-06 20:32:28 -08001402 if (ptr == SEQ_START_TOKEN) {
1403 seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1404 return 0;
1405 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406
1407 file = ptr->swap_file;
Jan Blunckc32c2f62008-02-14 19:38:43 -08001408 len = seq_path(swap, &file->f_path, " \t\n\\");
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001409 seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 len < 40 ? 40 - len : 1, " ",
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001411 S_ISBLK(file->f_path.dentry->d_inode->i_mode) ?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412 "partition" : "file\t",
1413 ptr->pages << (PAGE_SHIFT - 10),
1414 ptr->inuse_pages << (PAGE_SHIFT - 10),
1415 ptr->prio);
1416 return 0;
1417}
1418
Helge Deller15ad7cd2006-12-06 20:40:36 -08001419static const struct seq_operations swaps_op = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001420 .start = swap_start,
1421 .next = swap_next,
1422 .stop = swap_stop,
1423 .show = swap_show
1424};
1425
1426static int swaps_open(struct inode *inode, struct file *file)
1427{
1428 return seq_open(file, &swaps_op);
1429}
1430
Helge Deller15ad7cd2006-12-06 20:40:36 -08001431static const struct file_operations proc_swaps_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001432 .open = swaps_open,
1433 .read = seq_read,
1434 .llseek = seq_lseek,
1435 .release = seq_release,
1436};
1437
1438static int __init procswaps_init(void)
1439{
Denis V. Lunev3d71f862008-04-29 01:02:13 -07001440 proc_create("swaps", 0, NULL, &proc_swaps_operations);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441 return 0;
1442}
1443__initcall(procswaps_init);
1444#endif /* CONFIG_PROC_FS */
1445
1446/*
1447 * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
1448 *
1449 * The swapon system call
1450 */
1451asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
1452{
1453 struct swap_info_struct * p;
1454 char *name = NULL;
1455 struct block_device *bdev = NULL;
1456 struct file *swap_file = NULL;
1457 struct address_space *mapping;
1458 unsigned int type;
1459 int i, prev;
1460 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461 union swap_header *swap_header = NULL;
1462 int swap_header_version;
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001463 unsigned int nr_good_pages = 0;
1464 int nr_extents = 0;
Hugh Dickins53092a72005-09-03 15:54:34 -07001465 sector_t span;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466 unsigned long maxpages = 1;
1467 int swapfilesize;
Hugh Dickins78ecba02008-07-23 21:28:23 -07001468 unsigned short *swap_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001469 struct page *page = NULL;
1470 struct inode *inode = NULL;
1471 int did_down = 0;
1472
1473 if (!capable(CAP_SYS_ADMIN))
1474 return -EPERM;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001475 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001476 p = swap_info;
1477 for (type = 0 ; type < nr_swapfiles ; type++,p++)
1478 if (!(p->flags & SWP_USED))
1479 break;
1480 error = -EPERM;
Christoph Lameter06972122006-06-23 02:03:35 -07001481 if (type >= MAX_SWAPFILES) {
Hugh Dickins5d337b92005-09-03 15:54:41 -07001482 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001483 goto out;
1484 }
1485 if (type >= nr_swapfiles)
1486 nr_swapfiles = type+1;
Hugh Dickins78ecba02008-07-23 21:28:23 -07001487 memset(p, 0, sizeof(*p));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001488 INIT_LIST_HEAD(&p->extent_list);
1489 p->flags = SWP_USED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 p->next = -1;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001491 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492 name = getname(specialfile);
1493 error = PTR_ERR(name);
1494 if (IS_ERR(name)) {
1495 name = NULL;
1496 goto bad_swap_2;
1497 }
1498 swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0);
1499 error = PTR_ERR(swap_file);
1500 if (IS_ERR(swap_file)) {
1501 swap_file = NULL;
1502 goto bad_swap_2;
1503 }
1504
1505 p->swap_file = swap_file;
1506 mapping = swap_file->f_mapping;
1507 inode = mapping->host;
1508
1509 error = -EBUSY;
1510 for (i = 0; i < nr_swapfiles; i++) {
1511 struct swap_info_struct *q = &swap_info[i];
1512
1513 if (i == type || !q->swap_file)
1514 continue;
1515 if (mapping == q->swap_file->f_mapping)
1516 goto bad_swap;
1517 }
1518
1519 error = -EINVAL;
1520 if (S_ISBLK(inode->i_mode)) {
1521 bdev = I_BDEV(inode);
1522 error = bd_claim(bdev, sys_swapon);
1523 if (error < 0) {
1524 bdev = NULL;
Rob Landleyf7b3a432005-09-22 21:44:27 -07001525 error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001526 goto bad_swap;
1527 }
1528 p->old_block_size = block_size(bdev);
1529 error = set_blocksize(bdev, PAGE_SIZE);
1530 if (error < 0)
1531 goto bad_swap;
1532 p->bdev = bdev;
1533 } else if (S_ISREG(inode->i_mode)) {
1534 p->bdev = inode->i_sb->s_bdev;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001535 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536 did_down = 1;
1537 if (IS_SWAPFILE(inode)) {
1538 error = -EBUSY;
1539 goto bad_swap;
1540 }
1541 } else {
1542 goto bad_swap;
1543 }
1544
1545 swapfilesize = i_size_read(inode) >> PAGE_SHIFT;
1546
1547 /*
1548 * Read the swap header.
1549 */
1550 if (!mapping->a_ops->readpage) {
1551 error = -EINVAL;
1552 goto bad_swap;
1553 }
Pekka Enberg090d2b12006-06-23 02:05:08 -07001554 page = read_mapping_page(mapping, 0, swap_file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555 if (IS_ERR(page)) {
1556 error = PTR_ERR(page);
1557 goto bad_swap;
1558 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559 kmap(page);
1560 swap_header = page_address(page);
1561
1562 if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
1563 swap_header_version = 1;
1564 else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
1565 swap_header_version = 2;
1566 else {
Jesper Juhle97a3112006-01-11 01:50:28 +01001567 printk(KERN_ERR "Unable to find swap-space signature\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568 error = -EINVAL;
1569 goto bad_swap;
1570 }
1571
1572 switch (swap_header_version) {
1573 case 1:
1574 printk(KERN_ERR "version 0 swap is no longer supported. "
1575 "Use mkswap -v1 %s\n", name);
1576 error = -EINVAL;
1577 goto bad_swap;
1578 case 2:
Chris Dearman797df572008-04-28 02:12:19 -07001579 /* swap partition endianess hack... */
1580 if (swab32(swap_header->info.version) == 1) {
1581 swab32s(&swap_header->info.version);
1582 swab32s(&swap_header->info.last_page);
1583 swab32s(&swap_header->info.nr_badpages);
1584 for (i = 0; i < swap_header->info.nr_badpages; i++)
1585 swab32s(&swap_header->info.badpages[i]);
1586 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 /* Check the swap header's sub-version and the size of
1588 the swap file and bad block lists */
1589 if (swap_header->info.version != 1) {
1590 printk(KERN_WARNING
1591 "Unable to handle swap header version %d\n",
1592 swap_header->info.version);
1593 error = -EINVAL;
1594 goto bad_swap;
1595 }
1596
1597 p->lowest_bit = 1;
Hugh Dickins52b7efdb2005-09-03 15:54:39 -07001598 p->cluster_next = 1;
1599
Linus Torvalds1da177e2005-04-16 15:20:36 -07001600 /*
1601 * Find out how many pages are allowed for a single swap
1602 * device. There are two limiting factors: 1) the number of
1603 * bits for the swap offset in the swp_entry_t type and
1604 * 2) the number of bits in the a swap pte as defined by
1605 * the different architectures. In order to find the
1606 * largest possible bit mask a swap entry with swap type 0
1607 * and swap offset ~0UL is created, encoded to a swap pte,
1608 * decoded to a swp_entry_t again and finally the swap
1609 * offset is extracted. This will mask all the bits from
1610 * the initial ~0UL mask that can't be encoded in either
1611 * the swp_entry_t or the architecture definition of a
1612 * swap pte.
1613 */
1614 maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1;
1615 if (maxpages > swap_header->info.last_page)
1616 maxpages = swap_header->info.last_page;
1617 p->highest_bit = maxpages - 1;
1618
1619 error = -EINVAL;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001620 if (!maxpages)
1621 goto bad_swap;
Eric Sandeen5d1854e2006-12-06 20:33:06 -08001622 if (swapfilesize && maxpages > swapfilesize) {
1623 printk(KERN_WARNING
1624 "Swap area shorter than signature indicates\n");
1625 goto bad_swap;
1626 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001627 if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
1628 goto bad_swap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629 if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
1630 goto bad_swap;
Tobias Klausercd105df2006-01-08 01:00:59 -08001631
Linus Torvalds1da177e2005-04-16 15:20:36 -07001632 /* OK, set up the swap map and apply the bad block list */
Hugh Dickins78ecba02008-07-23 21:28:23 -07001633 swap_map = vmalloc(maxpages * sizeof(short));
1634 if (!swap_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635 error = -ENOMEM;
1636 goto bad_swap;
1637 }
1638
1639 error = 0;
Hugh Dickins78ecba02008-07-23 21:28:23 -07001640 memset(swap_map, 0, maxpages * sizeof(short));
Tobias Klausercd105df2006-01-08 01:00:59 -08001641 for (i = 0; i < swap_header->info.nr_badpages; i++) {
1642 int page_nr = swap_header->info.badpages[i];
1643 if (page_nr <= 0 || page_nr >= swap_header->info.last_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001644 error = -EINVAL;
1645 else
Hugh Dickins78ecba02008-07-23 21:28:23 -07001646 swap_map[page_nr] = SWAP_MAP_BAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001647 }
1648 nr_good_pages = swap_header->info.last_page -
1649 swap_header->info.nr_badpages -
1650 1 /* header page */;
Tobias Klausercd105df2006-01-08 01:00:59 -08001651 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652 goto bad_swap;
1653 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001654
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001655 if (nr_good_pages) {
Hugh Dickins78ecba02008-07-23 21:28:23 -07001656 swap_map[0] = SWAP_MAP_BAD;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001657 p->max = maxpages;
1658 p->pages = nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001659 nr_extents = setup_swap_extents(p, &span);
1660 if (nr_extents < 0) {
1661 error = nr_extents;
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001662 goto bad_swap;
Hugh Dickins53092a72005-09-03 15:54:34 -07001663 }
Hugh Dickinse2244ec2005-09-03 15:54:32 -07001664 nr_good_pages = p->pages;
1665 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001666 if (!nr_good_pages) {
1667 printk(KERN_WARNING "Empty swap-file\n");
1668 error = -EINVAL;
1669 goto bad_swap;
1670 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001671
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001672 mutex_lock(&swapon_mutex);
Hugh Dickins5d337b92005-09-03 15:54:41 -07001673 spin_lock(&swap_lock);
Hugh Dickins78ecba02008-07-23 21:28:23 -07001674 if (swap_flags & SWAP_FLAG_PREFER)
1675 p->prio =
1676 (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT;
1677 else
1678 p->prio = --least_priority;
1679 p->swap_map = swap_map;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680 p->flags = SWP_ACTIVE;
1681 nr_swap_pages += nr_good_pages;
1682 total_swap_pages += nr_good_pages;
Hugh Dickins53092a72005-09-03 15:54:34 -07001683
Hugh Dickins6eb396d2005-09-03 15:54:35 -07001684 printk(KERN_INFO "Adding %uk swap on %s. "
Hugh Dickins53092a72005-09-03 15:54:34 -07001685 "Priority:%d extents:%d across:%lluk\n",
1686 nr_good_pages<<(PAGE_SHIFT-10), name, p->prio,
1687 nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001688
1689 /* insert swap space into swap_list: */
1690 prev = -1;
1691 for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
1692 if (p->prio >= swap_info[i].prio) {
1693 break;
1694 }
1695 prev = i;
1696 }
1697 p->next = i;
1698 if (prev < 0) {
1699 swap_list.head = swap_list.next = p - swap_info;
1700 } else {
1701 swap_info[prev].next = p - swap_info;
1702 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001703 spin_unlock(&swap_lock);
Ingo Molnarfc0abb12006-01-18 17:42:33 -08001704 mutex_unlock(&swapon_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001705 error = 0;
1706 goto out;
1707bad_swap:
1708 if (bdev) {
1709 set_blocksize(bdev, p->old_block_size);
1710 bd_release(bdev);
1711 }
Hugh Dickins4cd3bb12005-09-03 15:54:33 -07001712 destroy_swap_extents(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001713bad_swap_2:
Hugh Dickins5d337b92005-09-03 15:54:41 -07001714 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715 p->swap_file = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716 p->flags = 0;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001717 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001718 vfree(swap_map);
1719 if (swap_file)
1720 filp_close(swap_file, NULL);
1721out:
1722 if (page && !IS_ERR(page)) {
1723 kunmap(page);
1724 page_cache_release(page);
1725 }
1726 if (name)
1727 putname(name);
1728 if (did_down) {
1729 if (!error)
1730 inode->i_flags |= S_SWAPFILE;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001731 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001732 }
1733 return error;
1734}
1735
1736void si_swapinfo(struct sysinfo *val)
1737{
1738 unsigned int i;
1739 unsigned long nr_to_be_unused = 0;
1740
Hugh Dickins5d337b92005-09-03 15:54:41 -07001741 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742 for (i = 0; i < nr_swapfiles; i++) {
1743 if (!(swap_info[i].flags & SWP_USED) ||
1744 (swap_info[i].flags & SWP_WRITEOK))
1745 continue;
1746 nr_to_be_unused += swap_info[i].inuse_pages;
1747 }
1748 val->freeswap = nr_swap_pages + nr_to_be_unused;
1749 val->totalswap = total_swap_pages + nr_to_be_unused;
Hugh Dickins5d337b92005-09-03 15:54:41 -07001750 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751}
1752
1753/*
1754 * Verify that a swap entry is valid and increment its swap map count.
1755 *
1756 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
1757 * "permanent", but will be reclaimed by the next swapoff.
1758 */
1759int swap_duplicate(swp_entry_t entry)
1760{
1761 struct swap_info_struct * p;
1762 unsigned long offset, type;
1763 int result = 0;
1764
Christoph Lameter06972122006-06-23 02:03:35 -07001765 if (is_migration_entry(entry))
1766 return 1;
1767
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768 type = swp_type(entry);
1769 if (type >= nr_swapfiles)
1770 goto bad_file;
1771 p = type + swap_info;
1772 offset = swp_offset(entry);
1773
Hugh Dickins5d337b92005-09-03 15:54:41 -07001774 spin_lock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001775 if (offset < p->max && p->swap_map[offset]) {
1776 if (p->swap_map[offset] < SWAP_MAP_MAX - 1) {
1777 p->swap_map[offset]++;
1778 result = 1;
1779 } else if (p->swap_map[offset] <= SWAP_MAP_MAX) {
1780 if (swap_overflow++ < 5)
1781 printk(KERN_WARNING "swap_dup: swap entry overflow\n");
1782 p->swap_map[offset] = SWAP_MAP_MAX;
1783 result = 1;
1784 }
1785 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001786 spin_unlock(&swap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787out:
1788 return result;
1789
1790bad_file:
1791 printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
1792 goto out;
1793}
1794
1795struct swap_info_struct *
1796get_swap_info_struct(unsigned type)
1797{
1798 return &swap_info[type];
1799}
1800
1801/*
Hugh Dickins5d337b92005-09-03 15:54:41 -07001802 * swap_lock prevents swap_map being freed. Don't grab an extra
Linus Torvalds1da177e2005-04-16 15:20:36 -07001803 * reference on the swaphandle, it doesn't matter if it becomes unused.
1804 */
1805int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
1806{
Hugh Dickins89528982008-02-04 22:28:45 -08001807 struct swap_info_struct *si;
Hugh Dickins3f9e7942006-09-29 02:01:26 -07001808 int our_page_cluster = page_cluster;
Hugh Dickins89528982008-02-04 22:28:45 -08001809 pgoff_t target, toff;
1810 pgoff_t base, end;
1811 int nr_pages = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001812
Hugh Dickins3f9e7942006-09-29 02:01:26 -07001813 if (!our_page_cluster) /* no readahead */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001814 return 0;
Hugh Dickins89528982008-02-04 22:28:45 -08001815
1816 si = &swap_info[swp_type(entry)];
1817 target = swp_offset(entry);
1818 base = (target >> our_page_cluster) << our_page_cluster;
1819 end = base + (1 << our_page_cluster);
1820 if (!base) /* first page is swap header */
1821 base++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001822
Hugh Dickins5d337b92005-09-03 15:54:41 -07001823 spin_lock(&swap_lock);
Hugh Dickins89528982008-02-04 22:28:45 -08001824 if (end > si->max) /* don't go beyond end of map */
1825 end = si->max;
1826
1827 /* Count contiguous allocated slots above our target */
1828 for (toff = target; ++toff < end; nr_pages++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001829 /* Don't read in free or bad pages */
Hugh Dickins89528982008-02-04 22:28:45 -08001830 if (!si->swap_map[toff])
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831 break;
Hugh Dickins89528982008-02-04 22:28:45 -08001832 if (si->swap_map[toff] == SWAP_MAP_BAD)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833 break;
Hugh Dickins89528982008-02-04 22:28:45 -08001834 }
1835 /* Count contiguous allocated slots below our target */
1836 for (toff = target; --toff >= base; nr_pages++) {
1837 /* Don't read in free or bad pages */
1838 if (!si->swap_map[toff])
1839 break;
1840 if (si->swap_map[toff] == SWAP_MAP_BAD)
1841 break;
1842 }
Hugh Dickins5d337b92005-09-03 15:54:41 -07001843 spin_unlock(&swap_lock);
Hugh Dickins89528982008-02-04 22:28:45 -08001844
1845 /*
1846 * Indicate starting offset, and return number of pages to get:
1847 * if only 1, say 0, since there's then no readahead to be done.
1848 */
1849 *offset = ++toff;
1850 return nr_pages? ++nr_pages: 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001851}