4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 * Swap reorganised 29.12.95, Stephen Tweedie
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/random.h>
20 #include <linux/writeback.h>
21 #include <linux/proc_fs.h>
22 #include <linux/seq_file.h>
23 #include <linux/init.h>
24 #include <linux/module.h>
25 #include <linux/rmap.h>
26 #include <linux/security.h>
27 #include <linux/backing-dev.h>
28 #include <linux/mutex.h>
29 #include <linux/capability.h>
30 #include <linux/syscalls.h>
31 #include <linux/memcontrol.h>
33 #include <asm/pgtable.h>
34 #include <asm/tlbflush.h>
35 #include <linux/swapops.h>
36 #include <linux/page_cgroup.h>
38 static DEFINE_SPINLOCK(swap_lock
);
39 static unsigned int nr_swapfiles
;
41 long total_swap_pages
;
42 static int swap_overflow
;
43 static int least_priority
;
45 static const char Bad_file
[] = "Bad swap file entry ";
46 static const char Unused_file
[] = "Unused swap file entry ";
47 static const char Bad_offset
[] = "Bad swap offset entry ";
48 static const char Unused_offset
[] = "Unused swap offset entry ";
50 static struct swap_list_t swap_list
= {-1, -1};
52 static struct swap_info_struct swap_info
[MAX_SWAPFILES
];
54 static DEFINE_MUTEX(swapon_mutex
);
56 /* For reference count accounting in swap_map */
57 /* enum for swap_map[] handling. internal use only */
59 SWAP_MAP
= 0, /* ops for reference from swap users */
60 SWAP_CACHE
, /* ops for reference from swap cache */
63 static inline int swap_count(unsigned short ent
)
65 return ent
& SWAP_COUNT_MASK
;
68 static inline bool swap_has_cache(unsigned short ent
)
70 return !!(ent
& SWAP_HAS_CACHE
);
73 static inline unsigned short encode_swapmap(int count
, bool has_cache
)
75 unsigned short ret
= count
;
78 return SWAP_HAS_CACHE
| ret
;
84 * We need this because the bdev->unplug_fn can sleep and we cannot
85 * hold swap_lock while calling the unplug_fn. And swap_lock
86 * cannot be turned into a mutex.
88 static DECLARE_RWSEM(swap_unplug_sem
);
90 void swap_unplug_io_fn(struct backing_dev_info
*unused_bdi
, struct page
*page
)
94 down_read(&swap_unplug_sem
);
95 entry
.val
= page_private(page
);
96 if (PageSwapCache(page
)) {
97 struct block_device
*bdev
= swap_info
[swp_type(entry
)].bdev
;
98 struct backing_dev_info
*bdi
;
101 * If the page is removed from swapcache from under us (with a
102 * racy try_to_unuse/swapoff) we need an additional reference
103 * count to avoid reading garbage from page_private(page) above.
104 * If the WARN_ON triggers during a swapoff it maybe the race
105 * condition and it's harmless. However if it triggers without
106 * swapoff it signals a problem.
108 WARN_ON(page_count(page
) <= 1);
110 bdi
= bdev
->bd_inode
->i_mapping
->backing_dev_info
;
111 blk_run_backing_dev(bdi
, page
);
113 up_read(&swap_unplug_sem
);
117 * swapon tell device that all the old swap contents can be discarded,
118 * to allow the swap device to optimize its wear-levelling.
120 static int discard_swap(struct swap_info_struct
*si
)
122 struct swap_extent
*se
;
125 list_for_each_entry(se
, &si
->extent_list
, list
) {
126 sector_t start_block
= se
->start_block
<< (PAGE_SHIFT
- 9);
127 sector_t nr_blocks
= (sector_t
)se
->nr_pages
<< (PAGE_SHIFT
- 9);
129 if (se
->start_page
== 0) {
130 /* Do not discard the swap header page! */
131 start_block
+= 1 << (PAGE_SHIFT
- 9);
132 nr_blocks
-= 1 << (PAGE_SHIFT
- 9);
137 err
= blkdev_issue_discard(si
->bdev
, start_block
,
138 nr_blocks
, GFP_KERNEL
);
144 return err
; /* That will often be -EOPNOTSUPP */
148 * swap allocation tell device that a cluster of swap can now be discarded,
149 * to allow the swap device to optimize its wear-levelling.
151 static void discard_swap_cluster(struct swap_info_struct
*si
,
152 pgoff_t start_page
, pgoff_t nr_pages
)
154 struct swap_extent
*se
= si
->curr_swap_extent
;
155 int found_extent
= 0;
158 struct list_head
*lh
;
160 if (se
->start_page
<= start_page
&&
161 start_page
< se
->start_page
+ se
->nr_pages
) {
162 pgoff_t offset
= start_page
- se
->start_page
;
163 sector_t start_block
= se
->start_block
+ offset
;
164 sector_t nr_blocks
= se
->nr_pages
- offset
;
166 if (nr_blocks
> nr_pages
)
167 nr_blocks
= nr_pages
;
168 start_page
+= nr_blocks
;
169 nr_pages
-= nr_blocks
;
172 si
->curr_swap_extent
= se
;
174 start_block
<<= PAGE_SHIFT
- 9;
175 nr_blocks
<<= PAGE_SHIFT
- 9;
176 if (blkdev_issue_discard(si
->bdev
, start_block
,
177 nr_blocks
, GFP_NOIO
))
182 if (lh
== &si
->extent_list
)
184 se
= list_entry(lh
, struct swap_extent
, list
);
188 static int wait_for_discard(void *word
)
194 #define SWAPFILE_CLUSTER 256
195 #define LATENCY_LIMIT 256
197 static inline unsigned long scan_swap_map(struct swap_info_struct
*si
,
200 unsigned long offset
;
201 unsigned long scan_base
;
202 unsigned long last_in_cluster
= 0;
203 int latency_ration
= LATENCY_LIMIT
;
204 int found_free_cluster
= 0;
207 * We try to cluster swap pages by allocating them sequentially
208 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this
209 * way, however, we resort to first-free allocation, starting
210 * a new cluster. This prevents us from scattering swap pages
211 * all over the entire swap partition, so that we reduce
212 * overall disk seek times between swap pages. -- sct
213 * But we do now try to find an empty cluster. -Andrea
214 * And we let swap pages go all over an SSD partition. Hugh
217 si
->flags
+= SWP_SCANNING
;
218 scan_base
= offset
= si
->cluster_next
;
220 if (unlikely(!si
->cluster_nr
--)) {
221 if (si
->pages
- si
->inuse_pages
< SWAPFILE_CLUSTER
) {
222 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
225 if (si
->flags
& SWP_DISCARDABLE
) {
227 * Start range check on racing allocations, in case
228 * they overlap the cluster we eventually decide on
229 * (we scan without swap_lock to allow preemption).
230 * It's hardly conceivable that cluster_nr could be
231 * wrapped during our scan, but don't depend on it.
233 if (si
->lowest_alloc
)
235 si
->lowest_alloc
= si
->max
;
236 si
->highest_alloc
= 0;
238 spin_unlock(&swap_lock
);
241 * If seek is expensive, start searching for new cluster from
242 * start of partition, to minimize the span of allocated swap.
243 * But if seek is cheap, search from our current position, so
244 * that swap is allocated from all over the partition: if the
245 * Flash Translation Layer only remaps within limited zones,
246 * we don't want to wear out the first zone too quickly.
248 if (!(si
->flags
& SWP_SOLIDSTATE
))
249 scan_base
= offset
= si
->lowest_bit
;
250 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
- 1;
252 /* Locate the first empty (unaligned) cluster */
253 for (; last_in_cluster
<= si
->highest_bit
; offset
++) {
254 if (si
->swap_map
[offset
])
255 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
;
256 else if (offset
== last_in_cluster
) {
257 spin_lock(&swap_lock
);
258 offset
-= SWAPFILE_CLUSTER
- 1;
259 si
->cluster_next
= offset
;
260 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
261 found_free_cluster
= 1;
264 if (unlikely(--latency_ration
< 0)) {
266 latency_ration
= LATENCY_LIMIT
;
270 offset
= si
->lowest_bit
;
271 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
- 1;
273 /* Locate the first empty (unaligned) cluster */
274 for (; last_in_cluster
< scan_base
; offset
++) {
275 if (si
->swap_map
[offset
])
276 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
;
277 else if (offset
== last_in_cluster
) {
278 spin_lock(&swap_lock
);
279 offset
-= SWAPFILE_CLUSTER
- 1;
280 si
->cluster_next
= offset
;
281 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
282 found_free_cluster
= 1;
285 if (unlikely(--latency_ration
< 0)) {
287 latency_ration
= LATENCY_LIMIT
;
292 spin_lock(&swap_lock
);
293 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
294 si
->lowest_alloc
= 0;
298 if (!(si
->flags
& SWP_WRITEOK
))
300 if (!si
->highest_bit
)
302 if (offset
> si
->highest_bit
)
303 scan_base
= offset
= si
->lowest_bit
;
304 if (si
->swap_map
[offset
])
307 if (offset
== si
->lowest_bit
)
309 if (offset
== si
->highest_bit
)
312 if (si
->inuse_pages
== si
->pages
) {
313 si
->lowest_bit
= si
->max
;
316 if (cache
== SWAP_CACHE
) /* at usual swap-out via vmscan.c */
317 si
->swap_map
[offset
] = encode_swapmap(0, true);
318 else /* at suspend */
319 si
->swap_map
[offset
] = encode_swapmap(1, false);
320 si
->cluster_next
= offset
+ 1;
321 si
->flags
-= SWP_SCANNING
;
323 if (si
->lowest_alloc
) {
325 * Only set when SWP_DISCARDABLE, and there's a scan
326 * for a free cluster in progress or just completed.
328 if (found_free_cluster
) {
330 * To optimize wear-levelling, discard the
331 * old data of the cluster, taking care not to
332 * discard any of its pages that have already
333 * been allocated by racing tasks (offset has
334 * already stepped over any at the beginning).
336 if (offset
< si
->highest_alloc
&&
337 si
->lowest_alloc
<= last_in_cluster
)
338 last_in_cluster
= si
->lowest_alloc
- 1;
339 si
->flags
|= SWP_DISCARDING
;
340 spin_unlock(&swap_lock
);
342 if (offset
< last_in_cluster
)
343 discard_swap_cluster(si
, offset
,
344 last_in_cluster
- offset
+ 1);
346 spin_lock(&swap_lock
);
347 si
->lowest_alloc
= 0;
348 si
->flags
&= ~SWP_DISCARDING
;
350 smp_mb(); /* wake_up_bit advises this */
351 wake_up_bit(&si
->flags
, ilog2(SWP_DISCARDING
));
353 } else if (si
->flags
& SWP_DISCARDING
) {
355 * Delay using pages allocated by racing tasks
356 * until the whole discard has been issued. We
357 * could defer that delay until swap_writepage,
358 * but it's easier to keep this self-contained.
360 spin_unlock(&swap_lock
);
361 wait_on_bit(&si
->flags
, ilog2(SWP_DISCARDING
),
362 wait_for_discard
, TASK_UNINTERRUPTIBLE
);
363 spin_lock(&swap_lock
);
366 * Note pages allocated by racing tasks while
367 * scan for a free cluster is in progress, so
368 * that its final discard can exclude them.
370 if (offset
< si
->lowest_alloc
)
371 si
->lowest_alloc
= offset
;
372 if (offset
> si
->highest_alloc
)
373 si
->highest_alloc
= offset
;
379 spin_unlock(&swap_lock
);
380 while (++offset
<= si
->highest_bit
) {
381 if (!si
->swap_map
[offset
]) {
382 spin_lock(&swap_lock
);
385 if (unlikely(--latency_ration
< 0)) {
387 latency_ration
= LATENCY_LIMIT
;
390 offset
= si
->lowest_bit
;
391 while (++offset
< scan_base
) {
392 if (!si
->swap_map
[offset
]) {
393 spin_lock(&swap_lock
);
396 if (unlikely(--latency_ration
< 0)) {
398 latency_ration
= LATENCY_LIMIT
;
401 spin_lock(&swap_lock
);
404 si
->flags
-= SWP_SCANNING
;
408 swp_entry_t
get_swap_page(void)
410 struct swap_info_struct
*si
;
415 spin_lock(&swap_lock
);
416 if (nr_swap_pages
<= 0)
420 for (type
= swap_list
.next
; type
>= 0 && wrapped
< 2; type
= next
) {
421 si
= swap_info
+ type
;
424 (!wrapped
&& si
->prio
!= swap_info
[next
].prio
)) {
425 next
= swap_list
.head
;
429 if (!si
->highest_bit
)
431 if (!(si
->flags
& SWP_WRITEOK
))
434 swap_list
.next
= next
;
435 /* This is called for allocating swap entry for cache */
436 offset
= scan_swap_map(si
, SWAP_CACHE
);
438 spin_unlock(&swap_lock
);
439 return swp_entry(type
, offset
);
441 next
= swap_list
.next
;
446 spin_unlock(&swap_lock
);
447 return (swp_entry_t
) {0};
450 /* The only caller of this function is now susupend routine */
451 swp_entry_t
get_swap_page_of_type(int type
)
453 struct swap_info_struct
*si
;
456 spin_lock(&swap_lock
);
457 si
= swap_info
+ type
;
458 if (si
->flags
& SWP_WRITEOK
) {
460 /* This is called for allocating swap entry, not cache */
461 offset
= scan_swap_map(si
, SWAP_MAP
);
463 spin_unlock(&swap_lock
);
464 return swp_entry(type
, offset
);
468 spin_unlock(&swap_lock
);
469 return (swp_entry_t
) {0};
472 static struct swap_info_struct
* swap_info_get(swp_entry_t entry
)
474 struct swap_info_struct
* p
;
475 unsigned long offset
, type
;
479 type
= swp_type(entry
);
480 if (type
>= nr_swapfiles
)
482 p
= & swap_info
[type
];
483 if (!(p
->flags
& SWP_USED
))
485 offset
= swp_offset(entry
);
486 if (offset
>= p
->max
)
488 if (!p
->swap_map
[offset
])
490 spin_lock(&swap_lock
);
494 printk(KERN_ERR
"swap_free: %s%08lx\n", Unused_offset
, entry
.val
);
497 printk(KERN_ERR
"swap_free: %s%08lx\n", Bad_offset
, entry
.val
);
500 printk(KERN_ERR
"swap_free: %s%08lx\n", Unused_file
, entry
.val
);
503 printk(KERN_ERR
"swap_free: %s%08lx\n", Bad_file
, entry
.val
);
508 static int swap_entry_free(struct swap_info_struct
*p
,
509 swp_entry_t ent
, int cache
)
511 unsigned long offset
= swp_offset(ent
);
512 int count
= swap_count(p
->swap_map
[offset
]);
515 has_cache
= swap_has_cache(p
->swap_map
[offset
]);
517 if (cache
== SWAP_MAP
) { /* dropping usage count of swap */
518 if (count
< SWAP_MAP_MAX
) {
520 p
->swap_map
[offset
] = encode_swapmap(count
, has_cache
);
522 } else { /* dropping swap cache flag */
523 VM_BUG_ON(!has_cache
);
524 p
->swap_map
[offset
] = encode_swapmap(count
, false);
528 count
= p
->swap_map
[offset
];
529 /* free if no reference */
531 if (offset
< p
->lowest_bit
)
532 p
->lowest_bit
= offset
;
533 if (offset
> p
->highest_bit
)
534 p
->highest_bit
= offset
;
535 if (p
->prio
> swap_info
[swap_list
.next
].prio
)
536 swap_list
.next
= p
- swap_info
;
539 mem_cgroup_uncharge_swap(ent
);
545 * Caller has made sure that the swapdevice corresponding to entry
546 * is still around or has not been recycled.
548 void swap_free(swp_entry_t entry
)
550 struct swap_info_struct
* p
;
552 p
= swap_info_get(entry
);
554 swap_entry_free(p
, entry
, SWAP_MAP
);
555 spin_unlock(&swap_lock
);
560 * Called after dropping swapcache to decrease refcnt to swap entries.
562 void swapcache_free(swp_entry_t entry
, struct page
*page
)
564 struct swap_info_struct
*p
;
567 mem_cgroup_uncharge_swapcache(page
, entry
);
568 p
= swap_info_get(entry
);
570 swap_entry_free(p
, entry
, SWAP_CACHE
);
571 spin_unlock(&swap_lock
);
577 * How many references to page are currently swapped out?
579 static inline int page_swapcount(struct page
*page
)
582 struct swap_info_struct
*p
;
585 entry
.val
= page_private(page
);
586 p
= swap_info_get(entry
);
588 count
= swap_count(p
->swap_map
[swp_offset(entry
)]);
589 spin_unlock(&swap_lock
);
595 * We can write to an anon page without COW if there are no other references
596 * to it. And as a side-effect, free up its swap: because the old content
597 * on disk will never be read, and seeking back there to write new content
598 * later would only waste time away from clustering.
600 int reuse_swap_page(struct page
*page
)
604 VM_BUG_ON(!PageLocked(page
));
605 count
= page_mapcount(page
);
606 if (count
<= 1 && PageSwapCache(page
)) {
607 count
+= page_swapcount(page
);
608 if (count
== 1 && !PageWriteback(page
)) {
609 delete_from_swap_cache(page
);
617 * If swap is getting full, or if there are no more mappings of this page,
618 * then try_to_free_swap is called to free its swap space.
620 int try_to_free_swap(struct page
*page
)
622 VM_BUG_ON(!PageLocked(page
));
624 if (!PageSwapCache(page
))
626 if (PageWriteback(page
))
628 if (page_swapcount(page
))
631 delete_from_swap_cache(page
);
637 * Free the swap entry like above, but also try to
638 * free the page cache entry if it is the last user.
640 int free_swap_and_cache(swp_entry_t entry
)
642 struct swap_info_struct
*p
;
643 struct page
*page
= NULL
;
645 if (is_migration_entry(entry
))
648 p
= swap_info_get(entry
);
650 if (swap_entry_free(p
, entry
, SWAP_MAP
) == SWAP_HAS_CACHE
) {
651 page
= find_get_page(&swapper_space
, entry
.val
);
652 if (page
&& !trylock_page(page
)) {
653 page_cache_release(page
);
657 spin_unlock(&swap_lock
);
661 * Not mapped elsewhere, or swap space full? Free it!
662 * Also recheck PageSwapCache now page is locked (above).
664 if (PageSwapCache(page
) && !PageWriteback(page
) &&
665 (!page_mapped(page
) || vm_swap_full())) {
666 delete_from_swap_cache(page
);
670 page_cache_release(page
);
675 #ifdef CONFIG_HIBERNATION
677 * Find the swap type that corresponds to given device (if any).
679 * @offset - number of the PAGE_SIZE-sized block of the device, starting
680 * from 0, in which the swap header is expected to be located.
682 * This is needed for the suspend to disk (aka swsusp).
684 int swap_type_of(dev_t device
, sector_t offset
, struct block_device
**bdev_p
)
686 struct block_device
*bdev
= NULL
;
690 bdev
= bdget(device
);
692 spin_lock(&swap_lock
);
693 for (i
= 0; i
< nr_swapfiles
; i
++) {
694 struct swap_info_struct
*sis
= swap_info
+ i
;
696 if (!(sis
->flags
& SWP_WRITEOK
))
701 *bdev_p
= bdget(sis
->bdev
->bd_dev
);
703 spin_unlock(&swap_lock
);
706 if (bdev
== sis
->bdev
) {
707 struct swap_extent
*se
;
709 se
= list_entry(sis
->extent_list
.next
,
710 struct swap_extent
, list
);
711 if (se
->start_block
== offset
) {
713 *bdev_p
= bdget(sis
->bdev
->bd_dev
);
715 spin_unlock(&swap_lock
);
721 spin_unlock(&swap_lock
);
729 * Return either the total number of swap pages of given type, or the number
730 * of free pages of that type (depending on @free)
732 * This is needed for software suspend
734 unsigned int count_swap_pages(int type
, int free
)
738 if (type
< nr_swapfiles
) {
739 spin_lock(&swap_lock
);
740 if (swap_info
[type
].flags
& SWP_WRITEOK
) {
741 n
= swap_info
[type
].pages
;
743 n
-= swap_info
[type
].inuse_pages
;
745 spin_unlock(&swap_lock
);
752 * No need to decide whether this PTE shares the swap entry with others,
753 * just let do_wp_page work it out if a write is requested later - to
754 * force COW, vm_page_prot omits write permission from any private vma.
756 static int unuse_pte(struct vm_area_struct
*vma
, pmd_t
*pmd
,
757 unsigned long addr
, swp_entry_t entry
, struct page
*page
)
759 struct mem_cgroup
*ptr
= NULL
;
764 if (mem_cgroup_try_charge_swapin(vma
->vm_mm
, page
, GFP_KERNEL
, &ptr
)) {
769 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
770 if (unlikely(!pte_same(*pte
, swp_entry_to_pte(entry
)))) {
772 mem_cgroup_cancel_charge_swapin(ptr
);
777 inc_mm_counter(vma
->vm_mm
, anon_rss
);
779 set_pte_at(vma
->vm_mm
, addr
, pte
,
780 pte_mkold(mk_pte(page
, vma
->vm_page_prot
)));
781 page_add_anon_rmap(page
, vma
, addr
);
782 mem_cgroup_commit_charge_swapin(page
, ptr
);
785 * Move the page to the active list so it is not
786 * immediately swapped out again after swapon.
790 pte_unmap_unlock(pte
, ptl
);
795 static int unuse_pte_range(struct vm_area_struct
*vma
, pmd_t
*pmd
,
796 unsigned long addr
, unsigned long end
,
797 swp_entry_t entry
, struct page
*page
)
799 pte_t swp_pte
= swp_entry_to_pte(entry
);
804 * We don't actually need pte lock while scanning for swp_pte: since
805 * we hold page lock and mmap_sem, swp_pte cannot be inserted into the
806 * page table while we're scanning; though it could get zapped, and on
807 * some architectures (e.g. x86_32 with PAE) we might catch a glimpse
808 * of unmatched parts which look like swp_pte, so unuse_pte must
809 * recheck under pte lock. Scanning without pte lock lets it be
810 * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE.
812 pte
= pte_offset_map(pmd
, addr
);
815 * swapoff spends a _lot_ of time in this loop!
816 * Test inline before going to call unuse_pte.
818 if (unlikely(pte_same(*pte
, swp_pte
))) {
820 ret
= unuse_pte(vma
, pmd
, addr
, entry
, page
);
823 pte
= pte_offset_map(pmd
, addr
);
825 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
831 static inline int unuse_pmd_range(struct vm_area_struct
*vma
, pud_t
*pud
,
832 unsigned long addr
, unsigned long end
,
833 swp_entry_t entry
, struct page
*page
)
839 pmd
= pmd_offset(pud
, addr
);
841 next
= pmd_addr_end(addr
, end
);
842 if (pmd_none_or_clear_bad(pmd
))
844 ret
= unuse_pte_range(vma
, pmd
, addr
, next
, entry
, page
);
847 } while (pmd
++, addr
= next
, addr
!= end
);
851 static inline int unuse_pud_range(struct vm_area_struct
*vma
, pgd_t
*pgd
,
852 unsigned long addr
, unsigned long end
,
853 swp_entry_t entry
, struct page
*page
)
859 pud
= pud_offset(pgd
, addr
);
861 next
= pud_addr_end(addr
, end
);
862 if (pud_none_or_clear_bad(pud
))
864 ret
= unuse_pmd_range(vma
, pud
, addr
, next
, entry
, page
);
867 } while (pud
++, addr
= next
, addr
!= end
);
871 static int unuse_vma(struct vm_area_struct
*vma
,
872 swp_entry_t entry
, struct page
*page
)
875 unsigned long addr
, end
, next
;
879 addr
= page_address_in_vma(page
, vma
);
883 end
= addr
+ PAGE_SIZE
;
885 addr
= vma
->vm_start
;
889 pgd
= pgd_offset(vma
->vm_mm
, addr
);
891 next
= pgd_addr_end(addr
, end
);
892 if (pgd_none_or_clear_bad(pgd
))
894 ret
= unuse_pud_range(vma
, pgd
, addr
, next
, entry
, page
);
897 } while (pgd
++, addr
= next
, addr
!= end
);
901 static int unuse_mm(struct mm_struct
*mm
,
902 swp_entry_t entry
, struct page
*page
)
904 struct vm_area_struct
*vma
;
907 if (!down_read_trylock(&mm
->mmap_sem
)) {
909 * Activate page so shrink_inactive_list is unlikely to unmap
910 * its ptes while lock is dropped, so swapoff can make progress.
914 down_read(&mm
->mmap_sem
);
917 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
918 if (vma
->anon_vma
&& (ret
= unuse_vma(vma
, entry
, page
)))
921 up_read(&mm
->mmap_sem
);
922 return (ret
< 0)? ret
: 0;
926 * Scan swap_map from current position to next entry still in use.
927 * Recycle to start on reaching the end, returning 0 when empty.
929 static unsigned int find_next_to_unuse(struct swap_info_struct
*si
,
932 unsigned int max
= si
->max
;
933 unsigned int i
= prev
;
937 * No need for swap_lock here: we're just looking
938 * for whether an entry is in use, not modifying it; false
939 * hits are okay, and sys_swapoff() has already prevented new
940 * allocations from this area (while holding swap_lock).
949 * No entries in use at top of swap_map,
950 * loop back to start and recheck there.
956 count
= si
->swap_map
[i
];
957 if (count
&& swap_count(count
) != SWAP_MAP_BAD
)
964 * We completely avoid races by reading each swap page in advance,
965 * and then search for the process using it. All the necessary
966 * page table adjustments can then be made atomically.
968 static int try_to_unuse(unsigned int type
)
970 struct swap_info_struct
* si
= &swap_info
[type
];
971 struct mm_struct
*start_mm
;
972 unsigned short *swap_map
;
973 unsigned short swcount
;
978 int reset_overflow
= 0;
982 * When searching mms for an entry, a good strategy is to
983 * start at the first mm we freed the previous entry from
984 * (though actually we don't notice whether we or coincidence
985 * freed the entry). Initialize this start_mm with a hold.
987 * A simpler strategy would be to start at the last mm we
988 * freed the previous entry from; but that would take less
989 * advantage of mmlist ordering, which clusters forked mms
990 * together, child after parent. If we race with dup_mmap(), we
991 * prefer to resolve parent before child, lest we miss entries
992 * duplicated after we scanned child: using last mm would invert
993 * that. Though it's only a serious concern when an overflowed
994 * swap count is reset from SWAP_MAP_MAX, preventing a rescan.
997 atomic_inc(&init_mm
.mm_users
);
1000 * Keep on scanning until all entries have gone. Usually,
1001 * one pass through swap_map is enough, but not necessarily:
1002 * there are races when an instance of an entry might be missed.
1004 while ((i
= find_next_to_unuse(si
, i
)) != 0) {
1005 if (signal_pending(current
)) {
1011 * Get a page for the entry, using the existing swap
1012 * cache page if there is one. Otherwise, get a clean
1013 * page and read the swap into it.
1015 swap_map
= &si
->swap_map
[i
];
1016 entry
= swp_entry(type
, i
);
1017 page
= read_swap_cache_async(entry
,
1018 GFP_HIGHUSER_MOVABLE
, NULL
, 0);
1021 * Either swap_duplicate() failed because entry
1022 * has been freed independently, and will not be
1023 * reused since sys_swapoff() already disabled
1024 * allocation from here, or alloc_page() failed.
1033 * Don't hold on to start_mm if it looks like exiting.
1035 if (atomic_read(&start_mm
->mm_users
) == 1) {
1037 start_mm
= &init_mm
;
1038 atomic_inc(&init_mm
.mm_users
);
1042 * Wait for and lock page. When do_swap_page races with
1043 * try_to_unuse, do_swap_page can handle the fault much
1044 * faster than try_to_unuse can locate the entry. This
1045 * apparently redundant "wait_on_page_locked" lets try_to_unuse
1046 * defer to do_swap_page in such a case - in some tests,
1047 * do_swap_page and try_to_unuse repeatedly compete.
1049 wait_on_page_locked(page
);
1050 wait_on_page_writeback(page
);
1052 wait_on_page_writeback(page
);
1055 * Remove all references to entry.
1056 * Whenever we reach init_mm, there's no address space
1057 * to search, but use it as a reminder to search shmem.
1060 swcount
= *swap_map
;
1061 if (swap_count(swcount
)) {
1062 if (start_mm
== &init_mm
)
1063 shmem
= shmem_unuse(entry
, page
);
1065 retval
= unuse_mm(start_mm
, entry
, page
);
1067 if (swap_count(*swap_map
)) {
1068 int set_start_mm
= (*swap_map
>= swcount
);
1069 struct list_head
*p
= &start_mm
->mmlist
;
1070 struct mm_struct
*new_start_mm
= start_mm
;
1071 struct mm_struct
*prev_mm
= start_mm
;
1072 struct mm_struct
*mm
;
1074 atomic_inc(&new_start_mm
->mm_users
);
1075 atomic_inc(&prev_mm
->mm_users
);
1076 spin_lock(&mmlist_lock
);
1077 while (swap_count(*swap_map
) && !retval
&& !shmem
&&
1078 (p
= p
->next
) != &start_mm
->mmlist
) {
1079 mm
= list_entry(p
, struct mm_struct
, mmlist
);
1080 if (!atomic_inc_not_zero(&mm
->mm_users
))
1082 spin_unlock(&mmlist_lock
);
1088 swcount
= *swap_map
;
1089 if (!swap_count(swcount
)) /* any usage ? */
1091 else if (mm
== &init_mm
) {
1093 shmem
= shmem_unuse(entry
, page
);
1095 retval
= unuse_mm(mm
, entry
, page
);
1098 swap_count(*swap_map
) < swcount
) {
1099 mmput(new_start_mm
);
1100 atomic_inc(&mm
->mm_users
);
1104 spin_lock(&mmlist_lock
);
1106 spin_unlock(&mmlist_lock
);
1109 start_mm
= new_start_mm
;
1112 /* page has already been unlocked and released */
1120 page_cache_release(page
);
1125 * How could swap count reach 0x7ffe ?
1126 * There's no way to repeat a swap page within an mm
1127 * (except in shmem, where it's the shared object which takes
1128 * the reference count)?
1129 * We believe SWAP_MAP_MAX cannot occur.(if occur, unsigned
1130 * short is too small....)
1131 * If that's wrong, then we should worry more about
1132 * exit_mmap() and do_munmap() cases described above:
1133 * we might be resetting SWAP_MAP_MAX too early here.
1134 * We know "Undead"s can happen, they're okay, so don't
1135 * report them; but do report if we reset SWAP_MAP_MAX.
1137 /* We might release the lock_page() in unuse_mm(). */
1138 if (!PageSwapCache(page
) || page_private(page
) != entry
.val
)
1141 if (swap_count(*swap_map
) == SWAP_MAP_MAX
) {
1142 spin_lock(&swap_lock
);
1143 *swap_map
= encode_swapmap(0, true);
1144 spin_unlock(&swap_lock
);
1149 * If a reference remains (rare), we would like to leave
1150 * the page in the swap cache; but try_to_unmap could
1151 * then re-duplicate the entry once we drop page lock,
1152 * so we might loop indefinitely; also, that page could
1153 * not be swapped out to other storage meanwhile. So:
1154 * delete from cache even if there's another reference,
1155 * after ensuring that the data has been saved to disk -
1156 * since if the reference remains (rarer), it will be
1157 * read from disk into another page. Splitting into two
1158 * pages would be incorrect if swap supported "shared
1159 * private" pages, but they are handled by tmpfs files.
1161 if (swap_count(*swap_map
) &&
1162 PageDirty(page
) && PageSwapCache(page
)) {
1163 struct writeback_control wbc
= {
1164 .sync_mode
= WB_SYNC_NONE
,
1167 swap_writepage(page
, &wbc
);
1169 wait_on_page_writeback(page
);
1173 * It is conceivable that a racing task removed this page from
1174 * swap cache just before we acquired the page lock at the top,
1175 * or while we dropped it in unuse_mm(). The page might even
1176 * be back in swap cache on another swap area: that we must not
1177 * delete, since it may not have been written out to swap yet.
1179 if (PageSwapCache(page
) &&
1180 likely(page_private(page
) == entry
.val
))
1181 delete_from_swap_cache(page
);
1184 * So we could skip searching mms once swap count went
1185 * to 1, we did not mark any present ptes as dirty: must
1186 * mark page dirty so shrink_page_list will preserve it.
1191 page_cache_release(page
);
1194 * Make sure that we aren't completely killing
1195 * interactive performance.
1201 if (reset_overflow
) {
1202 printk(KERN_WARNING
"swapoff: cleared swap entry overflow\n");
1209 * After a successful try_to_unuse, if no swap is now in use, we know
1210 * we can empty the mmlist. swap_lock must be held on entry and exit.
1211 * Note that mmlist_lock nests inside swap_lock, and an mm must be
1212 * added to the mmlist just after page_duplicate - before would be racy.
1214 static void drain_mmlist(void)
1216 struct list_head
*p
, *next
;
1219 for (i
= 0; i
< nr_swapfiles
; i
++)
1220 if (swap_info
[i
].inuse_pages
)
1222 spin_lock(&mmlist_lock
);
1223 list_for_each_safe(p
, next
, &init_mm
.mmlist
)
1225 spin_unlock(&mmlist_lock
);
1229 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
1230 * corresponds to page offset `offset'.
1232 sector_t
map_swap_page(struct swap_info_struct
*sis
, pgoff_t offset
)
1234 struct swap_extent
*se
= sis
->curr_swap_extent
;
1235 struct swap_extent
*start_se
= se
;
1238 struct list_head
*lh
;
1240 if (se
->start_page
<= offset
&&
1241 offset
< (se
->start_page
+ se
->nr_pages
)) {
1242 return se
->start_block
+ (offset
- se
->start_page
);
1245 if (lh
== &sis
->extent_list
)
1247 se
= list_entry(lh
, struct swap_extent
, list
);
1248 sis
->curr_swap_extent
= se
;
1249 BUG_ON(se
== start_se
); /* It *must* be present */
1253 #ifdef CONFIG_HIBERNATION
1255 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
1256 * corresponding to given index in swap_info (swap type).
1258 sector_t
swapdev_block(int swap_type
, pgoff_t offset
)
1260 struct swap_info_struct
*sis
;
1262 if (swap_type
>= nr_swapfiles
)
1265 sis
= swap_info
+ swap_type
;
1266 return (sis
->flags
& SWP_WRITEOK
) ? map_swap_page(sis
, offset
) : 0;
1268 #endif /* CONFIG_HIBERNATION */
1271 * Free all of a swapdev's extent information
1273 static void destroy_swap_extents(struct swap_info_struct
*sis
)
1275 while (!list_empty(&sis
->extent_list
)) {
1276 struct swap_extent
*se
;
1278 se
= list_entry(sis
->extent_list
.next
,
1279 struct swap_extent
, list
);
1280 list_del(&se
->list
);
1286 * Add a block range (and the corresponding page range) into this swapdev's
1287 * extent list. The extent list is kept sorted in page order.
1289 * This function rather assumes that it is called in ascending page order.
1292 add_swap_extent(struct swap_info_struct
*sis
, unsigned long start_page
,
1293 unsigned long nr_pages
, sector_t start_block
)
1295 struct swap_extent
*se
;
1296 struct swap_extent
*new_se
;
1297 struct list_head
*lh
;
1299 lh
= sis
->extent_list
.prev
; /* The highest page extent */
1300 if (lh
!= &sis
->extent_list
) {
1301 se
= list_entry(lh
, struct swap_extent
, list
);
1302 BUG_ON(se
->start_page
+ se
->nr_pages
!= start_page
);
1303 if (se
->start_block
+ se
->nr_pages
== start_block
) {
1305 se
->nr_pages
+= nr_pages
;
1311 * No merge. Insert a new extent, preserving ordering.
1313 new_se
= kmalloc(sizeof(*se
), GFP_KERNEL
);
1316 new_se
->start_page
= start_page
;
1317 new_se
->nr_pages
= nr_pages
;
1318 new_se
->start_block
= start_block
;
1320 list_add_tail(&new_se
->list
, &sis
->extent_list
);
1325 * A `swap extent' is a simple thing which maps a contiguous range of pages
1326 * onto a contiguous range of disk blocks. An ordered list of swap extents
1327 * is built at swapon time and is then used at swap_writepage/swap_readpage
1328 * time for locating where on disk a page belongs.
1330 * If the swapfile is an S_ISBLK block device, a single extent is installed.
1331 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
1332 * swap files identically.
1334 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
1335 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
1336 * swapfiles are handled *identically* after swapon time.
1338 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
1339 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
1340 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
1341 * requirements, they are simply tossed out - we will never use those blocks
1344 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
1345 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
1346 * which will scribble on the fs.
1348 * The amount of disk space which a single swap extent represents varies.
1349 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
1350 * extents in the list. To avoid much list walking, we cache the previous
1351 * search location in `curr_swap_extent', and start new searches from there.
1352 * This is extremely effective. The average number of iterations in
1353 * map_swap_page() has been measured at about 0.3 per page. - akpm.
1355 static int setup_swap_extents(struct swap_info_struct
*sis
, sector_t
*span
)
1357 struct inode
*inode
;
1358 unsigned blocks_per_page
;
1359 unsigned long page_no
;
1361 sector_t probe_block
;
1362 sector_t last_block
;
1363 sector_t lowest_block
= -1;
1364 sector_t highest_block
= 0;
1368 inode
= sis
->swap_file
->f_mapping
->host
;
1369 if (S_ISBLK(inode
->i_mode
)) {
1370 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
1375 blkbits
= inode
->i_blkbits
;
1376 blocks_per_page
= PAGE_SIZE
>> blkbits
;
1379 * Map all the blocks into the extent list. This code doesn't try
1384 last_block
= i_size_read(inode
) >> blkbits
;
1385 while ((probe_block
+ blocks_per_page
) <= last_block
&&
1386 page_no
< sis
->max
) {
1387 unsigned block_in_page
;
1388 sector_t first_block
;
1390 first_block
= bmap(inode
, probe_block
);
1391 if (first_block
== 0)
1395 * It must be PAGE_SIZE aligned on-disk
1397 if (first_block
& (blocks_per_page
- 1)) {
1402 for (block_in_page
= 1; block_in_page
< blocks_per_page
;
1406 block
= bmap(inode
, probe_block
+ block_in_page
);
1409 if (block
!= first_block
+ block_in_page
) {
1416 first_block
>>= (PAGE_SHIFT
- blkbits
);
1417 if (page_no
) { /* exclude the header page */
1418 if (first_block
< lowest_block
)
1419 lowest_block
= first_block
;
1420 if (first_block
> highest_block
)
1421 highest_block
= first_block
;
1425 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1427 ret
= add_swap_extent(sis
, page_no
, 1, first_block
);
1432 probe_block
+= blocks_per_page
;
1437 *span
= 1 + highest_block
- lowest_block
;
1439 page_no
= 1; /* force Empty message */
1441 sis
->pages
= page_no
- 1;
1442 sis
->highest_bit
= page_no
- 1;
1444 sis
->curr_swap_extent
= list_entry(sis
->extent_list
.prev
,
1445 struct swap_extent
, list
);
1448 printk(KERN_ERR
"swapon: swapfile has holes\n");
1454 SYSCALL_DEFINE1(swapoff
, const char __user
*, specialfile
)
1456 struct swap_info_struct
* p
= NULL
;
1457 unsigned short *swap_map
;
1458 struct file
*swap_file
, *victim
;
1459 struct address_space
*mapping
;
1460 struct inode
*inode
;
1465 if (!capable(CAP_SYS_ADMIN
))
1468 pathname
= getname(specialfile
);
1469 err
= PTR_ERR(pathname
);
1470 if (IS_ERR(pathname
))
1473 victim
= filp_open(pathname
, O_RDWR
|O_LARGEFILE
, 0);
1475 err
= PTR_ERR(victim
);
1479 mapping
= victim
->f_mapping
;
1481 spin_lock(&swap_lock
);
1482 for (type
= swap_list
.head
; type
>= 0; type
= swap_info
[type
].next
) {
1483 p
= swap_info
+ type
;
1484 if (p
->flags
& SWP_WRITEOK
) {
1485 if (p
->swap_file
->f_mapping
== mapping
)
1492 spin_unlock(&swap_lock
);
1495 if (!security_vm_enough_memory(p
->pages
))
1496 vm_unacct_memory(p
->pages
);
1499 spin_unlock(&swap_lock
);
1503 swap_list
.head
= p
->next
;
1505 swap_info
[prev
].next
= p
->next
;
1507 if (type
== swap_list
.next
) {
1508 /* just pick something that's safe... */
1509 swap_list
.next
= swap_list
.head
;
1512 for (i
= p
->next
; i
>= 0; i
= swap_info
[i
].next
)
1513 swap_info
[i
].prio
= p
->prio
--;
1516 nr_swap_pages
-= p
->pages
;
1517 total_swap_pages
-= p
->pages
;
1518 p
->flags
&= ~SWP_WRITEOK
;
1519 spin_unlock(&swap_lock
);
1521 current
->flags
|= PF_SWAPOFF
;
1522 err
= try_to_unuse(type
);
1523 current
->flags
&= ~PF_SWAPOFF
;
1526 /* re-insert swap space back into swap_list */
1527 spin_lock(&swap_lock
);
1529 p
->prio
= --least_priority
;
1531 for (i
= swap_list
.head
; i
>= 0; i
= swap_info
[i
].next
) {
1532 if (p
->prio
>= swap_info
[i
].prio
)
1538 swap_list
.head
= swap_list
.next
= p
- swap_info
;
1540 swap_info
[prev
].next
= p
- swap_info
;
1541 nr_swap_pages
+= p
->pages
;
1542 total_swap_pages
+= p
->pages
;
1543 p
->flags
|= SWP_WRITEOK
;
1544 spin_unlock(&swap_lock
);
1548 /* wait for any unplug function to finish */
1549 down_write(&swap_unplug_sem
);
1550 up_write(&swap_unplug_sem
);
1552 destroy_swap_extents(p
);
1553 mutex_lock(&swapon_mutex
);
1554 spin_lock(&swap_lock
);
1557 /* wait for anyone still in scan_swap_map */
1558 p
->highest_bit
= 0; /* cuts scans short */
1559 while (p
->flags
>= SWP_SCANNING
) {
1560 spin_unlock(&swap_lock
);
1561 schedule_timeout_uninterruptible(1);
1562 spin_lock(&swap_lock
);
1565 swap_file
= p
->swap_file
;
1566 p
->swap_file
= NULL
;
1568 swap_map
= p
->swap_map
;
1571 spin_unlock(&swap_lock
);
1572 mutex_unlock(&swapon_mutex
);
1574 /* Destroy swap account informatin */
1575 swap_cgroup_swapoff(type
);
1577 inode
= mapping
->host
;
1578 if (S_ISBLK(inode
->i_mode
)) {
1579 struct block_device
*bdev
= I_BDEV(inode
);
1580 set_blocksize(bdev
, p
->old_block_size
);
1583 mutex_lock(&inode
->i_mutex
);
1584 inode
->i_flags
&= ~S_SWAPFILE
;
1585 mutex_unlock(&inode
->i_mutex
);
1587 filp_close(swap_file
, NULL
);
1591 filp_close(victim
, NULL
);
1596 #ifdef CONFIG_PROC_FS
1598 static void *swap_start(struct seq_file
*swap
, loff_t
*pos
)
1600 struct swap_info_struct
*ptr
= swap_info
;
1604 mutex_lock(&swapon_mutex
);
1607 return SEQ_START_TOKEN
;
1609 for (i
= 0; i
< nr_swapfiles
; i
++, ptr
++) {
1610 if (!(ptr
->flags
& SWP_USED
) || !ptr
->swap_map
)
1619 static void *swap_next(struct seq_file
*swap
, void *v
, loff_t
*pos
)
1621 struct swap_info_struct
*ptr
;
1622 struct swap_info_struct
*endptr
= swap_info
+ nr_swapfiles
;
1624 if (v
== SEQ_START_TOKEN
)
1631 for (; ptr
< endptr
; ptr
++) {
1632 if (!(ptr
->flags
& SWP_USED
) || !ptr
->swap_map
)
1641 static void swap_stop(struct seq_file
*swap
, void *v
)
1643 mutex_unlock(&swapon_mutex
);
1646 static int swap_show(struct seq_file
*swap
, void *v
)
1648 struct swap_info_struct
*ptr
= v
;
1652 if (ptr
== SEQ_START_TOKEN
) {
1653 seq_puts(swap
,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1657 file
= ptr
->swap_file
;
1658 len
= seq_path(swap
, &file
->f_path
, " \t\n\\");
1659 seq_printf(swap
, "%*s%s\t%u\t%u\t%d\n",
1660 len
< 40 ? 40 - len
: 1, " ",
1661 S_ISBLK(file
->f_path
.dentry
->d_inode
->i_mode
) ?
1662 "partition" : "file\t",
1663 ptr
->pages
<< (PAGE_SHIFT
- 10),
1664 ptr
->inuse_pages
<< (PAGE_SHIFT
- 10),
1669 static const struct seq_operations swaps_op
= {
1670 .start
= swap_start
,
1676 static int swaps_open(struct inode
*inode
, struct file
*file
)
1678 return seq_open(file
, &swaps_op
);
1681 static const struct file_operations proc_swaps_operations
= {
1684 .llseek
= seq_lseek
,
1685 .release
= seq_release
,
1688 static int __init
procswaps_init(void)
1690 proc_create("swaps", 0, NULL
, &proc_swaps_operations
);
1693 __initcall(procswaps_init
);
1694 #endif /* CONFIG_PROC_FS */
1696 #ifdef MAX_SWAPFILES_CHECK
1697 static int __init
max_swapfiles_check(void)
1699 MAX_SWAPFILES_CHECK();
1702 late_initcall(max_swapfiles_check
);
1706 * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
1708 * The swapon system call
1710 SYSCALL_DEFINE2(swapon
, const char __user
*, specialfile
, int, swap_flags
)
1712 struct swap_info_struct
* p
;
1714 struct block_device
*bdev
= NULL
;
1715 struct file
*swap_file
= NULL
;
1716 struct address_space
*mapping
;
1720 union swap_header
*swap_header
= NULL
;
1721 unsigned int nr_good_pages
= 0;
1724 unsigned long maxpages
= 1;
1725 unsigned long swapfilepages
;
1726 unsigned short *swap_map
= NULL
;
1727 struct page
*page
= NULL
;
1728 struct inode
*inode
= NULL
;
1731 if (!capable(CAP_SYS_ADMIN
))
1733 spin_lock(&swap_lock
);
1735 for (type
= 0 ; type
< nr_swapfiles
; type
++,p
++)
1736 if (!(p
->flags
& SWP_USED
))
1739 if (type
>= MAX_SWAPFILES
) {
1740 spin_unlock(&swap_lock
);
1743 if (type
>= nr_swapfiles
)
1744 nr_swapfiles
= type
+1;
1745 memset(p
, 0, sizeof(*p
));
1746 INIT_LIST_HEAD(&p
->extent_list
);
1747 p
->flags
= SWP_USED
;
1749 spin_unlock(&swap_lock
);
1750 name
= getname(specialfile
);
1751 error
= PTR_ERR(name
);
1756 swap_file
= filp_open(name
, O_RDWR
|O_LARGEFILE
, 0);
1757 error
= PTR_ERR(swap_file
);
1758 if (IS_ERR(swap_file
)) {
1763 p
->swap_file
= swap_file
;
1764 mapping
= swap_file
->f_mapping
;
1765 inode
= mapping
->host
;
1768 for (i
= 0; i
< nr_swapfiles
; i
++) {
1769 struct swap_info_struct
*q
= &swap_info
[i
];
1771 if (i
== type
|| !q
->swap_file
)
1773 if (mapping
== q
->swap_file
->f_mapping
)
1778 if (S_ISBLK(inode
->i_mode
)) {
1779 bdev
= I_BDEV(inode
);
1780 error
= bd_claim(bdev
, sys_swapon
);
1786 p
->old_block_size
= block_size(bdev
);
1787 error
= set_blocksize(bdev
, PAGE_SIZE
);
1791 } else if (S_ISREG(inode
->i_mode
)) {
1792 p
->bdev
= inode
->i_sb
->s_bdev
;
1793 mutex_lock(&inode
->i_mutex
);
1795 if (IS_SWAPFILE(inode
)) {
1803 swapfilepages
= i_size_read(inode
) >> PAGE_SHIFT
;
1806 * Read the swap header.
1808 if (!mapping
->a_ops
->readpage
) {
1812 page
= read_mapping_page(mapping
, 0, swap_file
);
1814 error
= PTR_ERR(page
);
1817 swap_header
= kmap(page
);
1819 if (memcmp("SWAPSPACE2", swap_header
->magic
.magic
, 10)) {
1820 printk(KERN_ERR
"Unable to find swap-space signature\n");
1825 /* swap partition endianess hack... */
1826 if (swab32(swap_header
->info
.version
) == 1) {
1827 swab32s(&swap_header
->info
.version
);
1828 swab32s(&swap_header
->info
.last_page
);
1829 swab32s(&swap_header
->info
.nr_badpages
);
1830 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++)
1831 swab32s(&swap_header
->info
.badpages
[i
]);
1833 /* Check the swap header's sub-version */
1834 if (swap_header
->info
.version
!= 1) {
1836 "Unable to handle swap header version %d\n",
1837 swap_header
->info
.version
);
1843 p
->cluster_next
= 1;
1846 * Find out how many pages are allowed for a single swap
1847 * device. There are two limiting factors: 1) the number of
1848 * bits for the swap offset in the swp_entry_t type and
1849 * 2) the number of bits in the a swap pte as defined by
1850 * the different architectures. In order to find the
1851 * largest possible bit mask a swap entry with swap type 0
1852 * and swap offset ~0UL is created, encoded to a swap pte,
1853 * decoded to a swp_entry_t again and finally the swap
1854 * offset is extracted. This will mask all the bits from
1855 * the initial ~0UL mask that can't be encoded in either
1856 * the swp_entry_t or the architecture definition of a
1859 maxpages
= swp_offset(pte_to_swp_entry(
1860 swp_entry_to_pte(swp_entry(0, ~0UL)))) - 1;
1861 if (maxpages
> swap_header
->info
.last_page
)
1862 maxpages
= swap_header
->info
.last_page
;
1863 p
->highest_bit
= maxpages
- 1;
1868 if (swapfilepages
&& maxpages
> swapfilepages
) {
1870 "Swap area shorter than signature indicates\n");
1873 if (swap_header
->info
.nr_badpages
&& S_ISREG(inode
->i_mode
))
1875 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
1878 /* OK, set up the swap map and apply the bad block list */
1879 swap_map
= vmalloc(maxpages
* sizeof(short));
1885 memset(swap_map
, 0, maxpages
* sizeof(short));
1886 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++) {
1887 int page_nr
= swap_header
->info
.badpages
[i
];
1888 if (page_nr
<= 0 || page_nr
>= swap_header
->info
.last_page
) {
1892 swap_map
[page_nr
] = SWAP_MAP_BAD
;
1895 error
= swap_cgroup_swapon(type
, maxpages
);
1899 nr_good_pages
= swap_header
->info
.last_page
-
1900 swap_header
->info
.nr_badpages
-
1901 1 /* header page */;
1903 if (nr_good_pages
) {
1904 swap_map
[0] = SWAP_MAP_BAD
;
1906 p
->pages
= nr_good_pages
;
1907 nr_extents
= setup_swap_extents(p
, &span
);
1908 if (nr_extents
< 0) {
1912 nr_good_pages
= p
->pages
;
1914 if (!nr_good_pages
) {
1915 printk(KERN_WARNING
"Empty swap-file\n");
1920 if (blk_queue_nonrot(bdev_get_queue(p
->bdev
))) {
1921 p
->flags
|= SWP_SOLIDSTATE
;
1922 p
->cluster_next
= 1 + (random32() % p
->highest_bit
);
1924 if (discard_swap(p
) == 0)
1925 p
->flags
|= SWP_DISCARDABLE
;
1927 mutex_lock(&swapon_mutex
);
1928 spin_lock(&swap_lock
);
1929 if (swap_flags
& SWAP_FLAG_PREFER
)
1931 (swap_flags
& SWAP_FLAG_PRIO_MASK
) >> SWAP_FLAG_PRIO_SHIFT
;
1933 p
->prio
= --least_priority
;
1934 p
->swap_map
= swap_map
;
1935 p
->flags
|= SWP_WRITEOK
;
1936 nr_swap_pages
+= nr_good_pages
;
1937 total_swap_pages
+= nr_good_pages
;
1939 printk(KERN_INFO
"Adding %uk swap on %s. "
1940 "Priority:%d extents:%d across:%lluk %s%s\n",
1941 nr_good_pages
<<(PAGE_SHIFT
-10), name
, p
->prio
,
1942 nr_extents
, (unsigned long long)span
<<(PAGE_SHIFT
-10),
1943 (p
->flags
& SWP_SOLIDSTATE
) ? "SS" : "",
1944 (p
->flags
& SWP_DISCARDABLE
) ? "D" : "");
1946 /* insert swap space into swap_list: */
1948 for (i
= swap_list
.head
; i
>= 0; i
= swap_info
[i
].next
) {
1949 if (p
->prio
>= swap_info
[i
].prio
) {
1956 swap_list
.head
= swap_list
.next
= p
- swap_info
;
1958 swap_info
[prev
].next
= p
- swap_info
;
1960 spin_unlock(&swap_lock
);
1961 mutex_unlock(&swapon_mutex
);
1966 set_blocksize(bdev
, p
->old_block_size
);
1969 destroy_swap_extents(p
);
1970 swap_cgroup_swapoff(type
);
1972 spin_lock(&swap_lock
);
1973 p
->swap_file
= NULL
;
1975 spin_unlock(&swap_lock
);
1978 filp_close(swap_file
, NULL
);
1980 if (page
&& !IS_ERR(page
)) {
1982 page_cache_release(page
);
1988 inode
->i_flags
|= S_SWAPFILE
;
1989 mutex_unlock(&inode
->i_mutex
);
1994 void si_swapinfo(struct sysinfo
*val
)
1997 unsigned long nr_to_be_unused
= 0;
1999 spin_lock(&swap_lock
);
2000 for (i
= 0; i
< nr_swapfiles
; i
++) {
2001 if (!(swap_info
[i
].flags
& SWP_USED
) ||
2002 (swap_info
[i
].flags
& SWP_WRITEOK
))
2004 nr_to_be_unused
+= swap_info
[i
].inuse_pages
;
2006 val
->freeswap
= nr_swap_pages
+ nr_to_be_unused
;
2007 val
->totalswap
= total_swap_pages
+ nr_to_be_unused
;
2008 spin_unlock(&swap_lock
);
2012 * Verify that a swap entry is valid and increment its swap map count.
2014 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
2015 * "permanent", but will be reclaimed by the next swapoff.
2016 * Returns error code in following case.
2018 * - swp_entry is invalid -> EINVAL
2019 * - swp_entry is migration entry -> EINVAL
2020 * - swap-cache reference is requested but there is already one. -> EEXIST
2021 * - swap-cache reference is requested but the entry is not used. -> ENOENT
2023 static int __swap_duplicate(swp_entry_t entry
, bool cache
)
2025 struct swap_info_struct
* p
;
2026 unsigned long offset
, type
;
2027 int result
= -EINVAL
;
2031 if (is_migration_entry(entry
))
2034 type
= swp_type(entry
);
2035 if (type
>= nr_swapfiles
)
2037 p
= type
+ swap_info
;
2038 offset
= swp_offset(entry
);
2040 spin_lock(&swap_lock
);
2042 if (unlikely(offset
>= p
->max
))
2045 count
= swap_count(p
->swap_map
[offset
]);
2046 has_cache
= swap_has_cache(p
->swap_map
[offset
]);
2048 if (cache
== SWAP_CACHE
) { /* called for swapcache/swapin-readahead */
2050 /* set SWAP_HAS_CACHE if there is no cache and entry is used */
2051 if (!has_cache
&& count
) {
2052 p
->swap_map
[offset
] = encode_swapmap(count
, true);
2054 } else if (has_cache
) /* someone added cache */
2056 else if (!count
) /* no users */
2059 } else if (count
|| has_cache
) {
2060 if (count
< SWAP_MAP_MAX
- 1) {
2061 p
->swap_map
[offset
] = encode_swapmap(count
+ 1,
2064 } else if (count
<= SWAP_MAP_MAX
) {
2065 if (swap_overflow
++ < 5)
2067 "swap_dup: swap entry overflow\n");
2068 p
->swap_map
[offset
] = encode_swapmap(SWAP_MAP_MAX
,
2073 result
= -ENOENT
; /* unused swap entry */
2075 spin_unlock(&swap_lock
);
2080 printk(KERN_ERR
"swap_dup: %s%08lx\n", Bad_file
, entry
.val
);
2084 * increase reference count of swap entry by 1.
2086 void swap_duplicate(swp_entry_t entry
)
2088 __swap_duplicate(entry
, SWAP_MAP
);
2092 * @entry: swap entry for which we allocate swap cache.
2094 * Called when allocating swap cache for exising swap entry,
2095 * This can return error codes. Returns 0 at success.
2096 * -EBUSY means there is a swap cache.
2097 * Note: return code is different from swap_duplicate().
2099 int swapcache_prepare(swp_entry_t entry
)
2101 return __swap_duplicate(entry
, SWAP_CACHE
);
2105 struct swap_info_struct
*
2106 get_swap_info_struct(unsigned type
)
2108 return &swap_info
[type
];
2112 * swap_lock prevents swap_map being freed. Don't grab an extra
2113 * reference on the swaphandle, it doesn't matter if it becomes unused.
2115 int valid_swaphandles(swp_entry_t entry
, unsigned long *offset
)
2117 struct swap_info_struct
*si
;
2118 int our_page_cluster
= page_cluster
;
2119 pgoff_t target
, toff
;
2123 if (!our_page_cluster
) /* no readahead */
2126 si
= &swap_info
[swp_type(entry
)];
2127 target
= swp_offset(entry
);
2128 base
= (target
>> our_page_cluster
) << our_page_cluster
;
2129 end
= base
+ (1 << our_page_cluster
);
2130 if (!base
) /* first page is swap header */
2133 spin_lock(&swap_lock
);
2134 if (end
> si
->max
) /* don't go beyond end of map */
2137 /* Count contiguous allocated slots above our target */
2138 for (toff
= target
; ++toff
< end
; nr_pages
++) {
2139 /* Don't read in free or bad pages */
2140 if (!si
->swap_map
[toff
])
2142 if (swap_count(si
->swap_map
[toff
]) == SWAP_MAP_BAD
)
2145 /* Count contiguous allocated slots below our target */
2146 for (toff
= target
; --toff
>= base
; nr_pages
++) {
2147 /* Don't read in free or bad pages */
2148 if (!si
->swap_map
[toff
])
2150 if (swap_count(si
->swap_map
[toff
]) == SWAP_MAP_BAD
)
2153 spin_unlock(&swap_lock
);
2156 * Indicate starting offset, and return number of pages to get:
2157 * if only 1, say 0, since there's then no readahead to be done.
2160 return nr_pages
? ++nr_pages
: 0;