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/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>
27 #include <linux/mutex.h>
28 #include <linux/capability.h>
29 #include <linux/syscalls.h>
30 #include <linux/memcontrol.h>
32 #include <asm/pgtable.h>
33 #include <asm/tlbflush.h>
34 #include <linux/swapops.h>
36 static DEFINE_SPINLOCK(swap_lock
);
37 static unsigned int nr_swapfiles
;
39 long total_swap_pages
;
40 static int swap_overflow
;
41 static int least_priority
;
43 static const char Bad_file
[] = "Bad swap file entry ";
44 static const char Unused_file
[] = "Unused swap file entry ";
45 static const char Bad_offset
[] = "Bad swap offset entry ";
46 static const char Unused_offset
[] = "Unused swap offset entry ";
48 static struct swap_list_t swap_list
= {-1, -1};
50 static struct swap_info_struct swap_info
[MAX_SWAPFILES
];
52 static DEFINE_MUTEX(swapon_mutex
);
55 * We need this because the bdev->unplug_fn can sleep and we cannot
56 * hold swap_lock while calling the unplug_fn. And swap_lock
57 * cannot be turned into a mutex.
59 static DECLARE_RWSEM(swap_unplug_sem
);
61 void swap_unplug_io_fn(struct backing_dev_info
*unused_bdi
, struct page
*page
)
65 down_read(&swap_unplug_sem
);
66 entry
.val
= page_private(page
);
67 if (PageSwapCache(page
)) {
68 struct block_device
*bdev
= swap_info
[swp_type(entry
)].bdev
;
69 struct backing_dev_info
*bdi
;
72 * If the page is removed from swapcache from under us (with a
73 * racy try_to_unuse/swapoff) we need an additional reference
74 * count to avoid reading garbage from page_private(page) above.
75 * If the WARN_ON triggers during a swapoff it maybe the race
76 * condition and it's harmless. However if it triggers without
77 * swapoff it signals a problem.
79 WARN_ON(page_count(page
) <= 1);
81 bdi
= bdev
->bd_inode
->i_mapping
->backing_dev_info
;
82 blk_run_backing_dev(bdi
, page
);
84 up_read(&swap_unplug_sem
);
88 * swapon tell device that all the old swap contents can be discarded,
89 * to allow the swap device to optimize its wear-levelling.
91 static int discard_swap(struct swap_info_struct
*si
)
93 struct swap_extent
*se
;
96 list_for_each_entry(se
, &si
->extent_list
, list
) {
97 sector_t start_block
= se
->start_block
<< (PAGE_SHIFT
- 9);
98 pgoff_t nr_blocks
= se
->nr_pages
<< (PAGE_SHIFT
- 9);
100 if (se
->start_page
== 0) {
101 /* Do not discard the swap header page! */
102 start_block
+= 1 << (PAGE_SHIFT
- 9);
103 nr_blocks
-= 1 << (PAGE_SHIFT
- 9);
108 err
= blkdev_issue_discard(si
->bdev
, start_block
,
109 nr_blocks
, GFP_KERNEL
);
115 return err
; /* That will often be -EOPNOTSUPP */
119 * swap allocation tell device that a cluster of swap can now be discarded,
120 * to allow the swap device to optimize its wear-levelling.
122 static void discard_swap_cluster(struct swap_info_struct
*si
,
123 pgoff_t start_page
, pgoff_t nr_pages
)
125 struct swap_extent
*se
= si
->curr_swap_extent
;
126 int found_extent
= 0;
129 struct list_head
*lh
;
131 if (se
->start_page
<= start_page
&&
132 start_page
< se
->start_page
+ se
->nr_pages
) {
133 pgoff_t offset
= start_page
- se
->start_page
;
134 sector_t start_block
= se
->start_block
+ offset
;
135 pgoff_t nr_blocks
= se
->nr_pages
- offset
;
137 if (nr_blocks
> nr_pages
)
138 nr_blocks
= nr_pages
;
139 start_page
+= nr_blocks
;
140 nr_pages
-= nr_blocks
;
143 si
->curr_swap_extent
= se
;
145 start_block
<<= PAGE_SHIFT
- 9;
146 nr_blocks
<<= PAGE_SHIFT
- 9;
147 if (blkdev_issue_discard(si
->bdev
, start_block
,
148 nr_blocks
, GFP_NOIO
))
153 if (lh
== &si
->extent_list
)
155 se
= list_entry(lh
, struct swap_extent
, list
);
159 static int wait_for_discard(void *word
)
165 #define SWAPFILE_CLUSTER 256
166 #define LATENCY_LIMIT 256
168 static inline unsigned long scan_swap_map(struct swap_info_struct
*si
)
170 unsigned long offset
;
171 unsigned long last_in_cluster
= 0;
172 int latency_ration
= LATENCY_LIMIT
;
173 int found_free_cluster
= 0;
176 * We try to cluster swap pages by allocating them sequentially
177 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this
178 * way, however, we resort to first-free allocation, starting
179 * a new cluster. This prevents us from scattering swap pages
180 * all over the entire swap partition, so that we reduce
181 * overall disk seek times between swap pages. -- sct
182 * But we do now try to find an empty cluster. -Andrea
185 si
->flags
+= SWP_SCANNING
;
186 offset
= si
->cluster_next
;
188 if (unlikely(!si
->cluster_nr
--)) {
189 if (si
->pages
- si
->inuse_pages
< SWAPFILE_CLUSTER
) {
190 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
193 if (si
->flags
& SWP_DISCARDABLE
) {
195 * Start range check on racing allocations, in case
196 * they overlap the cluster we eventually decide on
197 * (we scan without swap_lock to allow preemption).
198 * It's hardly conceivable that cluster_nr could be
199 * wrapped during our scan, but don't depend on it.
201 if (si
->lowest_alloc
)
203 si
->lowest_alloc
= si
->max
;
204 si
->highest_alloc
= 0;
206 spin_unlock(&swap_lock
);
208 offset
= si
->lowest_bit
;
209 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
- 1;
211 /* Locate the first empty (unaligned) cluster */
212 for (; last_in_cluster
<= si
->highest_bit
; offset
++) {
213 if (si
->swap_map
[offset
])
214 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
;
215 else if (offset
== last_in_cluster
) {
216 spin_lock(&swap_lock
);
217 offset
-= SWAPFILE_CLUSTER
- 1;
218 si
->cluster_next
= offset
;
219 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
220 found_free_cluster
= 1;
223 if (unlikely(--latency_ration
< 0)) {
225 latency_ration
= LATENCY_LIMIT
;
229 offset
= si
->lowest_bit
;
230 spin_lock(&swap_lock
);
231 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
232 si
->lowest_alloc
= 0;
236 if (!(si
->flags
& SWP_WRITEOK
))
238 if (!si
->highest_bit
)
240 if (offset
> si
->highest_bit
)
241 offset
= si
->lowest_bit
;
242 if (si
->swap_map
[offset
])
245 if (offset
== si
->lowest_bit
)
247 if (offset
== si
->highest_bit
)
250 if (si
->inuse_pages
== si
->pages
) {
251 si
->lowest_bit
= si
->max
;
254 si
->swap_map
[offset
] = 1;
255 si
->cluster_next
= offset
+ 1;
256 si
->flags
-= SWP_SCANNING
;
258 if (si
->lowest_alloc
) {
260 * Only set when SWP_DISCARDABLE, and there's a scan
261 * for a free cluster in progress or just completed.
263 if (found_free_cluster
) {
265 * To optimize wear-levelling, discard the
266 * old data of the cluster, taking care not to
267 * discard any of its pages that have already
268 * been allocated by racing tasks (offset has
269 * already stepped over any at the beginning).
271 if (offset
< si
->highest_alloc
&&
272 si
->lowest_alloc
<= last_in_cluster
)
273 last_in_cluster
= si
->lowest_alloc
- 1;
274 si
->flags
|= SWP_DISCARDING
;
275 spin_unlock(&swap_lock
);
277 if (offset
< last_in_cluster
)
278 discard_swap_cluster(si
, offset
,
279 last_in_cluster
- offset
+ 1);
281 spin_lock(&swap_lock
);
282 si
->lowest_alloc
= 0;
283 si
->flags
&= ~SWP_DISCARDING
;
285 smp_mb(); /* wake_up_bit advises this */
286 wake_up_bit(&si
->flags
, ilog2(SWP_DISCARDING
));
288 } else if (si
->flags
& SWP_DISCARDING
) {
290 * Delay using pages allocated by racing tasks
291 * until the whole discard has been issued. We
292 * could defer that delay until swap_writepage,
293 * but it's easier to keep this self-contained.
295 spin_unlock(&swap_lock
);
296 wait_on_bit(&si
->flags
, ilog2(SWP_DISCARDING
),
297 wait_for_discard
, TASK_UNINTERRUPTIBLE
);
298 spin_lock(&swap_lock
);
301 * Note pages allocated by racing tasks while
302 * scan for a free cluster is in progress, so
303 * that its final discard can exclude them.
305 if (offset
< si
->lowest_alloc
)
306 si
->lowest_alloc
= offset
;
307 if (offset
> si
->highest_alloc
)
308 si
->highest_alloc
= offset
;
314 spin_unlock(&swap_lock
);
315 while (++offset
<= si
->highest_bit
) {
316 if (!si
->swap_map
[offset
]) {
317 spin_lock(&swap_lock
);
320 if (unlikely(--latency_ration
< 0)) {
322 latency_ration
= LATENCY_LIMIT
;
325 spin_lock(&swap_lock
);
329 si
->flags
-= SWP_SCANNING
;
333 swp_entry_t
get_swap_page(void)
335 struct swap_info_struct
*si
;
340 spin_lock(&swap_lock
);
341 if (nr_swap_pages
<= 0)
345 for (type
= swap_list
.next
; type
>= 0 && wrapped
< 2; type
= next
) {
346 si
= swap_info
+ type
;
349 (!wrapped
&& si
->prio
!= swap_info
[next
].prio
)) {
350 next
= swap_list
.head
;
354 if (!si
->highest_bit
)
356 if (!(si
->flags
& SWP_WRITEOK
))
359 swap_list
.next
= next
;
360 offset
= scan_swap_map(si
);
362 spin_unlock(&swap_lock
);
363 return swp_entry(type
, offset
);
365 next
= swap_list
.next
;
370 spin_unlock(&swap_lock
);
371 return (swp_entry_t
) {0};
374 swp_entry_t
get_swap_page_of_type(int type
)
376 struct swap_info_struct
*si
;
379 spin_lock(&swap_lock
);
380 si
= swap_info
+ type
;
381 if (si
->flags
& SWP_WRITEOK
) {
383 offset
= scan_swap_map(si
);
385 spin_unlock(&swap_lock
);
386 return swp_entry(type
, offset
);
390 spin_unlock(&swap_lock
);
391 return (swp_entry_t
) {0};
394 static struct swap_info_struct
* swap_info_get(swp_entry_t entry
)
396 struct swap_info_struct
* p
;
397 unsigned long offset
, type
;
401 type
= swp_type(entry
);
402 if (type
>= nr_swapfiles
)
404 p
= & swap_info
[type
];
405 if (!(p
->flags
& SWP_USED
))
407 offset
= swp_offset(entry
);
408 if (offset
>= p
->max
)
410 if (!p
->swap_map
[offset
])
412 spin_lock(&swap_lock
);
416 printk(KERN_ERR
"swap_free: %s%08lx\n", Unused_offset
, entry
.val
);
419 printk(KERN_ERR
"swap_free: %s%08lx\n", Bad_offset
, entry
.val
);
422 printk(KERN_ERR
"swap_free: %s%08lx\n", Unused_file
, entry
.val
);
425 printk(KERN_ERR
"swap_free: %s%08lx\n", Bad_file
, entry
.val
);
430 static int swap_entry_free(struct swap_info_struct
*p
, unsigned long offset
)
432 int count
= p
->swap_map
[offset
];
434 if (count
< SWAP_MAP_MAX
) {
436 p
->swap_map
[offset
] = count
;
438 if (offset
< p
->lowest_bit
)
439 p
->lowest_bit
= offset
;
440 if (offset
> p
->highest_bit
)
441 p
->highest_bit
= offset
;
442 if (p
->prio
> swap_info
[swap_list
.next
].prio
)
443 swap_list
.next
= p
- swap_info
;
452 * Caller has made sure that the swapdevice corresponding to entry
453 * is still around or has not been recycled.
455 void swap_free(swp_entry_t entry
)
457 struct swap_info_struct
* p
;
459 p
= swap_info_get(entry
);
461 swap_entry_free(p
, swp_offset(entry
));
462 spin_unlock(&swap_lock
);
467 * How many references to page are currently swapped out?
469 static inline int page_swapcount(struct page
*page
)
472 struct swap_info_struct
*p
;
475 entry
.val
= page_private(page
);
476 p
= swap_info_get(entry
);
478 /* Subtract the 1 for the swap cache itself */
479 count
= p
->swap_map
[swp_offset(entry
)] - 1;
480 spin_unlock(&swap_lock
);
486 * We can write to an anon page without COW if there are no other references
487 * to it. And as a side-effect, free up its swap: because the old content
488 * on disk will never be read, and seeking back there to write new content
489 * later would only waste time away from clustering.
491 int reuse_swap_page(struct page
*page
)
495 VM_BUG_ON(!PageLocked(page
));
496 count
= page_mapcount(page
);
497 if (count
<= 1 && PageSwapCache(page
)) {
498 count
+= page_swapcount(page
);
499 if (count
== 1 && !PageWriteback(page
)) {
500 delete_from_swap_cache(page
);
508 * If swap is getting full, or if there are no more mappings of this page,
509 * then try_to_free_swap is called to free its swap space.
511 int try_to_free_swap(struct page
*page
)
513 VM_BUG_ON(!PageLocked(page
));
515 if (!PageSwapCache(page
))
517 if (PageWriteback(page
))
519 if (page_swapcount(page
))
522 delete_from_swap_cache(page
);
528 * Free the swap entry like above, but also try to
529 * free the page cache entry if it is the last user.
531 void free_swap_and_cache(swp_entry_t entry
)
533 struct swap_info_struct
* p
;
534 struct page
*page
= NULL
;
536 if (is_migration_entry(entry
))
539 p
= swap_info_get(entry
);
541 if (swap_entry_free(p
, swp_offset(entry
)) == 1) {
542 page
= find_get_page(&swapper_space
, entry
.val
);
543 if (page
&& !trylock_page(page
)) {
544 page_cache_release(page
);
548 spin_unlock(&swap_lock
);
552 * Not mapped elsewhere, or swap space full? Free it!
553 * Also recheck PageSwapCache now page is locked (above).
555 if (PageSwapCache(page
) && !PageWriteback(page
) &&
556 (!page_mapped(page
) || vm_swap_full())) {
557 delete_from_swap_cache(page
);
561 page_cache_release(page
);
565 #ifdef CONFIG_HIBERNATION
567 * Find the swap type that corresponds to given device (if any).
569 * @offset - number of the PAGE_SIZE-sized block of the device, starting
570 * from 0, in which the swap header is expected to be located.
572 * This is needed for the suspend to disk (aka swsusp).
574 int swap_type_of(dev_t device
, sector_t offset
, struct block_device
**bdev_p
)
576 struct block_device
*bdev
= NULL
;
580 bdev
= bdget(device
);
582 spin_lock(&swap_lock
);
583 for (i
= 0; i
< nr_swapfiles
; i
++) {
584 struct swap_info_struct
*sis
= swap_info
+ i
;
586 if (!(sis
->flags
& SWP_WRITEOK
))
593 spin_unlock(&swap_lock
);
596 if (bdev
== sis
->bdev
) {
597 struct swap_extent
*se
;
599 se
= list_entry(sis
->extent_list
.next
,
600 struct swap_extent
, list
);
601 if (se
->start_block
== offset
) {
605 spin_unlock(&swap_lock
);
611 spin_unlock(&swap_lock
);
619 * Return either the total number of swap pages of given type, or the number
620 * of free pages of that type (depending on @free)
622 * This is needed for software suspend
624 unsigned int count_swap_pages(int type
, int free
)
628 if (type
< nr_swapfiles
) {
629 spin_lock(&swap_lock
);
630 if (swap_info
[type
].flags
& SWP_WRITEOK
) {
631 n
= swap_info
[type
].pages
;
633 n
-= swap_info
[type
].inuse_pages
;
635 spin_unlock(&swap_lock
);
642 * No need to decide whether this PTE shares the swap entry with others,
643 * just let do_wp_page work it out if a write is requested later - to
644 * force COW, vm_page_prot omits write permission from any private vma.
646 static int unuse_pte(struct vm_area_struct
*vma
, pmd_t
*pmd
,
647 unsigned long addr
, swp_entry_t entry
, struct page
*page
)
653 if (mem_cgroup_charge(page
, vma
->vm_mm
, GFP_KERNEL
))
656 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
657 if (unlikely(!pte_same(*pte
, swp_entry_to_pte(entry
)))) {
659 mem_cgroup_uncharge_page(page
);
664 inc_mm_counter(vma
->vm_mm
, anon_rss
);
666 set_pte_at(vma
->vm_mm
, addr
, pte
,
667 pte_mkold(mk_pte(page
, vma
->vm_page_prot
)));
668 page_add_anon_rmap(page
, vma
, addr
);
671 * Move the page to the active list so it is not
672 * immediately swapped out again after swapon.
676 pte_unmap_unlock(pte
, ptl
);
680 static int unuse_pte_range(struct vm_area_struct
*vma
, pmd_t
*pmd
,
681 unsigned long addr
, unsigned long end
,
682 swp_entry_t entry
, struct page
*page
)
684 pte_t swp_pte
= swp_entry_to_pte(entry
);
689 * We don't actually need pte lock while scanning for swp_pte: since
690 * we hold page lock and mmap_sem, swp_pte cannot be inserted into the
691 * page table while we're scanning; though it could get zapped, and on
692 * some architectures (e.g. x86_32 with PAE) we might catch a glimpse
693 * of unmatched parts which look like swp_pte, so unuse_pte must
694 * recheck under pte lock. Scanning without pte lock lets it be
695 * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE.
697 pte
= pte_offset_map(pmd
, addr
);
700 * swapoff spends a _lot_ of time in this loop!
701 * Test inline before going to call unuse_pte.
703 if (unlikely(pte_same(*pte
, swp_pte
))) {
705 ret
= unuse_pte(vma
, pmd
, addr
, entry
, page
);
708 pte
= pte_offset_map(pmd
, addr
);
710 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
716 static inline int unuse_pmd_range(struct vm_area_struct
*vma
, pud_t
*pud
,
717 unsigned long addr
, unsigned long end
,
718 swp_entry_t entry
, struct page
*page
)
724 pmd
= pmd_offset(pud
, addr
);
726 next
= pmd_addr_end(addr
, end
);
727 if (pmd_none_or_clear_bad(pmd
))
729 ret
= unuse_pte_range(vma
, pmd
, addr
, next
, entry
, page
);
732 } while (pmd
++, addr
= next
, addr
!= end
);
736 static inline int unuse_pud_range(struct vm_area_struct
*vma
, pgd_t
*pgd
,
737 unsigned long addr
, unsigned long end
,
738 swp_entry_t entry
, struct page
*page
)
744 pud
= pud_offset(pgd
, addr
);
746 next
= pud_addr_end(addr
, end
);
747 if (pud_none_or_clear_bad(pud
))
749 ret
= unuse_pmd_range(vma
, pud
, addr
, next
, entry
, page
);
752 } while (pud
++, addr
= next
, addr
!= end
);
756 static int unuse_vma(struct vm_area_struct
*vma
,
757 swp_entry_t entry
, struct page
*page
)
760 unsigned long addr
, end
, next
;
764 addr
= page_address_in_vma(page
, vma
);
768 end
= addr
+ PAGE_SIZE
;
770 addr
= vma
->vm_start
;
774 pgd
= pgd_offset(vma
->vm_mm
, addr
);
776 next
= pgd_addr_end(addr
, end
);
777 if (pgd_none_or_clear_bad(pgd
))
779 ret
= unuse_pud_range(vma
, pgd
, addr
, next
, entry
, page
);
782 } while (pgd
++, addr
= next
, addr
!= end
);
786 static int unuse_mm(struct mm_struct
*mm
,
787 swp_entry_t entry
, struct page
*page
)
789 struct vm_area_struct
*vma
;
792 if (!down_read_trylock(&mm
->mmap_sem
)) {
794 * Activate page so shrink_inactive_list is unlikely to unmap
795 * its ptes while lock is dropped, so swapoff can make progress.
799 down_read(&mm
->mmap_sem
);
802 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
803 if (vma
->anon_vma
&& (ret
= unuse_vma(vma
, entry
, page
)))
806 up_read(&mm
->mmap_sem
);
807 return (ret
< 0)? ret
: 0;
811 * Scan swap_map from current position to next entry still in use.
812 * Recycle to start on reaching the end, returning 0 when empty.
814 static unsigned int find_next_to_unuse(struct swap_info_struct
*si
,
817 unsigned int max
= si
->max
;
818 unsigned int i
= prev
;
822 * No need for swap_lock here: we're just looking
823 * for whether an entry is in use, not modifying it; false
824 * hits are okay, and sys_swapoff() has already prevented new
825 * allocations from this area (while holding swap_lock).
834 * No entries in use at top of swap_map,
835 * loop back to start and recheck there.
841 count
= si
->swap_map
[i
];
842 if (count
&& count
!= SWAP_MAP_BAD
)
849 * We completely avoid races by reading each swap page in advance,
850 * and then search for the process using it. All the necessary
851 * page table adjustments can then be made atomically.
853 static int try_to_unuse(unsigned int type
)
855 struct swap_info_struct
* si
= &swap_info
[type
];
856 struct mm_struct
*start_mm
;
857 unsigned short *swap_map
;
858 unsigned short swcount
;
863 int reset_overflow
= 0;
867 * When searching mms for an entry, a good strategy is to
868 * start at the first mm we freed the previous entry from
869 * (though actually we don't notice whether we or coincidence
870 * freed the entry). Initialize this start_mm with a hold.
872 * A simpler strategy would be to start at the last mm we
873 * freed the previous entry from; but that would take less
874 * advantage of mmlist ordering, which clusters forked mms
875 * together, child after parent. If we race with dup_mmap(), we
876 * prefer to resolve parent before child, lest we miss entries
877 * duplicated after we scanned child: using last mm would invert
878 * that. Though it's only a serious concern when an overflowed
879 * swap count is reset from SWAP_MAP_MAX, preventing a rescan.
882 atomic_inc(&init_mm
.mm_users
);
885 * Keep on scanning until all entries have gone. Usually,
886 * one pass through swap_map is enough, but not necessarily:
887 * there are races when an instance of an entry might be missed.
889 while ((i
= find_next_to_unuse(si
, i
)) != 0) {
890 if (signal_pending(current
)) {
896 * Get a page for the entry, using the existing swap
897 * cache page if there is one. Otherwise, get a clean
898 * page and read the swap into it.
900 swap_map
= &si
->swap_map
[i
];
901 entry
= swp_entry(type
, i
);
902 page
= read_swap_cache_async(entry
,
903 GFP_HIGHUSER_MOVABLE
, NULL
, 0);
906 * Either swap_duplicate() failed because entry
907 * has been freed independently, and will not be
908 * reused since sys_swapoff() already disabled
909 * allocation from here, or alloc_page() failed.
918 * Don't hold on to start_mm if it looks like exiting.
920 if (atomic_read(&start_mm
->mm_users
) == 1) {
923 atomic_inc(&init_mm
.mm_users
);
927 * Wait for and lock page. When do_swap_page races with
928 * try_to_unuse, do_swap_page can handle the fault much
929 * faster than try_to_unuse can locate the entry. This
930 * apparently redundant "wait_on_page_locked" lets try_to_unuse
931 * defer to do_swap_page in such a case - in some tests,
932 * do_swap_page and try_to_unuse repeatedly compete.
934 wait_on_page_locked(page
);
935 wait_on_page_writeback(page
);
937 wait_on_page_writeback(page
);
940 * Remove all references to entry.
941 * Whenever we reach init_mm, there's no address space
942 * to search, but use it as a reminder to search shmem.
947 if (start_mm
== &init_mm
)
948 shmem
= shmem_unuse(entry
, page
);
950 retval
= unuse_mm(start_mm
, entry
, page
);
953 int set_start_mm
= (*swap_map
>= swcount
);
954 struct list_head
*p
= &start_mm
->mmlist
;
955 struct mm_struct
*new_start_mm
= start_mm
;
956 struct mm_struct
*prev_mm
= start_mm
;
957 struct mm_struct
*mm
;
959 atomic_inc(&new_start_mm
->mm_users
);
960 atomic_inc(&prev_mm
->mm_users
);
961 spin_lock(&mmlist_lock
);
962 while (*swap_map
> 1 && !retval
&& !shmem
&&
963 (p
= p
->next
) != &start_mm
->mmlist
) {
964 mm
= list_entry(p
, struct mm_struct
, mmlist
);
965 if (!atomic_inc_not_zero(&mm
->mm_users
))
967 spin_unlock(&mmlist_lock
);
976 else if (mm
== &init_mm
) {
978 shmem
= shmem_unuse(entry
, page
);
980 retval
= unuse_mm(mm
, entry
, page
);
981 if (set_start_mm
&& *swap_map
< swcount
) {
983 atomic_inc(&mm
->mm_users
);
987 spin_lock(&mmlist_lock
);
989 spin_unlock(&mmlist_lock
);
992 start_mm
= new_start_mm
;
995 /* page has already been unlocked and released */
1003 page_cache_release(page
);
1008 * How could swap count reach 0x7fff when the maximum
1009 * pid is 0x7fff, and there's no way to repeat a swap
1010 * page within an mm (except in shmem, where it's the
1011 * shared object which takes the reference count)?
1012 * We believe SWAP_MAP_MAX cannot occur in Linux 2.4.
1014 * If that's wrong, then we should worry more about
1015 * exit_mmap() and do_munmap() cases described above:
1016 * we might be resetting SWAP_MAP_MAX too early here.
1017 * We know "Undead"s can happen, they're okay, so don't
1018 * report them; but do report if we reset SWAP_MAP_MAX.
1020 if (*swap_map
== SWAP_MAP_MAX
) {
1021 spin_lock(&swap_lock
);
1023 spin_unlock(&swap_lock
);
1028 * If a reference remains (rare), we would like to leave
1029 * the page in the swap cache; but try_to_unmap could
1030 * then re-duplicate the entry once we drop page lock,
1031 * so we might loop indefinitely; also, that page could
1032 * not be swapped out to other storage meanwhile. So:
1033 * delete from cache even if there's another reference,
1034 * after ensuring that the data has been saved to disk -
1035 * since if the reference remains (rarer), it will be
1036 * read from disk into another page. Splitting into two
1037 * pages would be incorrect if swap supported "shared
1038 * private" pages, but they are handled by tmpfs files.
1040 if ((*swap_map
> 1) && PageDirty(page
) && PageSwapCache(page
)) {
1041 struct writeback_control wbc
= {
1042 .sync_mode
= WB_SYNC_NONE
,
1045 swap_writepage(page
, &wbc
);
1047 wait_on_page_writeback(page
);
1051 * It is conceivable that a racing task removed this page from
1052 * swap cache just before we acquired the page lock at the top,
1053 * or while we dropped it in unuse_mm(). The page might even
1054 * be back in swap cache on another swap area: that we must not
1055 * delete, since it may not have been written out to swap yet.
1057 if (PageSwapCache(page
) &&
1058 likely(page_private(page
) == entry
.val
))
1059 delete_from_swap_cache(page
);
1062 * So we could skip searching mms once swap count went
1063 * to 1, we did not mark any present ptes as dirty: must
1064 * mark page dirty so shrink_page_list will preserve it.
1068 page_cache_release(page
);
1071 * Make sure that we aren't completely killing
1072 * interactive performance.
1078 if (reset_overflow
) {
1079 printk(KERN_WARNING
"swapoff: cleared swap entry overflow\n");
1086 * After a successful try_to_unuse, if no swap is now in use, we know
1087 * we can empty the mmlist. swap_lock must be held on entry and exit.
1088 * Note that mmlist_lock nests inside swap_lock, and an mm must be
1089 * added to the mmlist just after page_duplicate - before would be racy.
1091 static void drain_mmlist(void)
1093 struct list_head
*p
, *next
;
1096 for (i
= 0; i
< nr_swapfiles
; i
++)
1097 if (swap_info
[i
].inuse_pages
)
1099 spin_lock(&mmlist_lock
);
1100 list_for_each_safe(p
, next
, &init_mm
.mmlist
)
1102 spin_unlock(&mmlist_lock
);
1106 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
1107 * corresponds to page offset `offset'.
1109 sector_t
map_swap_page(struct swap_info_struct
*sis
, pgoff_t offset
)
1111 struct swap_extent
*se
= sis
->curr_swap_extent
;
1112 struct swap_extent
*start_se
= se
;
1115 struct list_head
*lh
;
1117 if (se
->start_page
<= offset
&&
1118 offset
< (se
->start_page
+ se
->nr_pages
)) {
1119 return se
->start_block
+ (offset
- se
->start_page
);
1122 if (lh
== &sis
->extent_list
)
1124 se
= list_entry(lh
, struct swap_extent
, list
);
1125 sis
->curr_swap_extent
= se
;
1126 BUG_ON(se
== start_se
); /* It *must* be present */
1130 #ifdef CONFIG_HIBERNATION
1132 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
1133 * corresponding to given index in swap_info (swap type).
1135 sector_t
swapdev_block(int swap_type
, pgoff_t offset
)
1137 struct swap_info_struct
*sis
;
1139 if (swap_type
>= nr_swapfiles
)
1142 sis
= swap_info
+ swap_type
;
1143 return (sis
->flags
& SWP_WRITEOK
) ? map_swap_page(sis
, offset
) : 0;
1145 #endif /* CONFIG_HIBERNATION */
1148 * Free all of a swapdev's extent information
1150 static void destroy_swap_extents(struct swap_info_struct
*sis
)
1152 while (!list_empty(&sis
->extent_list
)) {
1153 struct swap_extent
*se
;
1155 se
= list_entry(sis
->extent_list
.next
,
1156 struct swap_extent
, list
);
1157 list_del(&se
->list
);
1163 * Add a block range (and the corresponding page range) into this swapdev's
1164 * extent list. The extent list is kept sorted in page order.
1166 * This function rather assumes that it is called in ascending page order.
1169 add_swap_extent(struct swap_info_struct
*sis
, unsigned long start_page
,
1170 unsigned long nr_pages
, sector_t start_block
)
1172 struct swap_extent
*se
;
1173 struct swap_extent
*new_se
;
1174 struct list_head
*lh
;
1176 lh
= sis
->extent_list
.prev
; /* The highest page extent */
1177 if (lh
!= &sis
->extent_list
) {
1178 se
= list_entry(lh
, struct swap_extent
, list
);
1179 BUG_ON(se
->start_page
+ se
->nr_pages
!= start_page
);
1180 if (se
->start_block
+ se
->nr_pages
== start_block
) {
1182 se
->nr_pages
+= nr_pages
;
1188 * No merge. Insert a new extent, preserving ordering.
1190 new_se
= kmalloc(sizeof(*se
), GFP_KERNEL
);
1193 new_se
->start_page
= start_page
;
1194 new_se
->nr_pages
= nr_pages
;
1195 new_se
->start_block
= start_block
;
1197 list_add_tail(&new_se
->list
, &sis
->extent_list
);
1202 * A `swap extent' is a simple thing which maps a contiguous range of pages
1203 * onto a contiguous range of disk blocks. An ordered list of swap extents
1204 * is built at swapon time and is then used at swap_writepage/swap_readpage
1205 * time for locating where on disk a page belongs.
1207 * If the swapfile is an S_ISBLK block device, a single extent is installed.
1208 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
1209 * swap files identically.
1211 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
1212 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
1213 * swapfiles are handled *identically* after swapon time.
1215 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
1216 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
1217 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
1218 * requirements, they are simply tossed out - we will never use those blocks
1221 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
1222 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
1223 * which will scribble on the fs.
1225 * The amount of disk space which a single swap extent represents varies.
1226 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
1227 * extents in the list. To avoid much list walking, we cache the previous
1228 * search location in `curr_swap_extent', and start new searches from there.
1229 * This is extremely effective. The average number of iterations in
1230 * map_swap_page() has been measured at about 0.3 per page. - akpm.
1232 static int setup_swap_extents(struct swap_info_struct
*sis
, sector_t
*span
)
1234 struct inode
*inode
;
1235 unsigned blocks_per_page
;
1236 unsigned long page_no
;
1238 sector_t probe_block
;
1239 sector_t last_block
;
1240 sector_t lowest_block
= -1;
1241 sector_t highest_block
= 0;
1245 inode
= sis
->swap_file
->f_mapping
->host
;
1246 if (S_ISBLK(inode
->i_mode
)) {
1247 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
1252 blkbits
= inode
->i_blkbits
;
1253 blocks_per_page
= PAGE_SIZE
>> blkbits
;
1256 * Map all the blocks into the extent list. This code doesn't try
1261 last_block
= i_size_read(inode
) >> blkbits
;
1262 while ((probe_block
+ blocks_per_page
) <= last_block
&&
1263 page_no
< sis
->max
) {
1264 unsigned block_in_page
;
1265 sector_t first_block
;
1267 first_block
= bmap(inode
, probe_block
);
1268 if (first_block
== 0)
1272 * It must be PAGE_SIZE aligned on-disk
1274 if (first_block
& (blocks_per_page
- 1)) {
1279 for (block_in_page
= 1; block_in_page
< blocks_per_page
;
1283 block
= bmap(inode
, probe_block
+ block_in_page
);
1286 if (block
!= first_block
+ block_in_page
) {
1293 first_block
>>= (PAGE_SHIFT
- blkbits
);
1294 if (page_no
) { /* exclude the header page */
1295 if (first_block
< lowest_block
)
1296 lowest_block
= first_block
;
1297 if (first_block
> highest_block
)
1298 highest_block
= first_block
;
1302 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1304 ret
= add_swap_extent(sis
, page_no
, 1, first_block
);
1309 probe_block
+= blocks_per_page
;
1314 *span
= 1 + highest_block
- lowest_block
;
1316 page_no
= 1; /* force Empty message */
1318 sis
->pages
= page_no
- 1;
1319 sis
->highest_bit
= page_no
- 1;
1321 sis
->curr_swap_extent
= list_entry(sis
->extent_list
.prev
,
1322 struct swap_extent
, list
);
1325 printk(KERN_ERR
"swapon: swapfile has holes\n");
1331 #if 0 /* We don't need this yet */
1332 #include <linux/backing-dev.h>
1333 int page_queue_congested(struct page
*page
)
1335 struct backing_dev_info
*bdi
;
1337 VM_BUG_ON(!PageLocked(page
)); /* It pins the swap_info_struct */
1339 if (PageSwapCache(page
)) {
1340 swp_entry_t entry
= { .val
= page_private(page
) };
1341 struct swap_info_struct
*sis
;
1343 sis
= get_swap_info_struct(swp_type(entry
));
1344 bdi
= sis
->bdev
->bd_inode
->i_mapping
->backing_dev_info
;
1346 bdi
= page
->mapping
->backing_dev_info
;
1347 return bdi_write_congested(bdi
);
1351 asmlinkage
long sys_swapoff(const char __user
* specialfile
)
1353 struct swap_info_struct
* p
= NULL
;
1354 unsigned short *swap_map
;
1355 struct file
*swap_file
, *victim
;
1356 struct address_space
*mapping
;
1357 struct inode
*inode
;
1362 if (!capable(CAP_SYS_ADMIN
))
1365 pathname
= getname(specialfile
);
1366 err
= PTR_ERR(pathname
);
1367 if (IS_ERR(pathname
))
1370 victim
= filp_open(pathname
, O_RDWR
|O_LARGEFILE
, 0);
1372 err
= PTR_ERR(victim
);
1376 mapping
= victim
->f_mapping
;
1378 spin_lock(&swap_lock
);
1379 for (type
= swap_list
.head
; type
>= 0; type
= swap_info
[type
].next
) {
1380 p
= swap_info
+ type
;
1381 if (p
->flags
& SWP_WRITEOK
) {
1382 if (p
->swap_file
->f_mapping
== mapping
)
1389 spin_unlock(&swap_lock
);
1392 if (!security_vm_enough_memory(p
->pages
))
1393 vm_unacct_memory(p
->pages
);
1396 spin_unlock(&swap_lock
);
1400 swap_list
.head
= p
->next
;
1402 swap_info
[prev
].next
= p
->next
;
1404 if (type
== swap_list
.next
) {
1405 /* just pick something that's safe... */
1406 swap_list
.next
= swap_list
.head
;
1409 for (i
= p
->next
; i
>= 0; i
= swap_info
[i
].next
)
1410 swap_info
[i
].prio
= p
->prio
--;
1413 nr_swap_pages
-= p
->pages
;
1414 total_swap_pages
-= p
->pages
;
1415 p
->flags
&= ~SWP_WRITEOK
;
1416 spin_unlock(&swap_lock
);
1418 current
->flags
|= PF_SWAPOFF
;
1419 err
= try_to_unuse(type
);
1420 current
->flags
&= ~PF_SWAPOFF
;
1423 /* re-insert swap space back into swap_list */
1424 spin_lock(&swap_lock
);
1426 p
->prio
= --least_priority
;
1428 for (i
= swap_list
.head
; i
>= 0; i
= swap_info
[i
].next
) {
1429 if (p
->prio
>= swap_info
[i
].prio
)
1435 swap_list
.head
= swap_list
.next
= p
- swap_info
;
1437 swap_info
[prev
].next
= p
- swap_info
;
1438 nr_swap_pages
+= p
->pages
;
1439 total_swap_pages
+= p
->pages
;
1440 p
->flags
|= SWP_WRITEOK
;
1441 spin_unlock(&swap_lock
);
1445 /* wait for any unplug function to finish */
1446 down_write(&swap_unplug_sem
);
1447 up_write(&swap_unplug_sem
);
1449 destroy_swap_extents(p
);
1450 mutex_lock(&swapon_mutex
);
1451 spin_lock(&swap_lock
);
1454 /* wait for anyone still in scan_swap_map */
1455 p
->highest_bit
= 0; /* cuts scans short */
1456 while (p
->flags
>= SWP_SCANNING
) {
1457 spin_unlock(&swap_lock
);
1458 schedule_timeout_uninterruptible(1);
1459 spin_lock(&swap_lock
);
1462 swap_file
= p
->swap_file
;
1463 p
->swap_file
= NULL
;
1465 swap_map
= p
->swap_map
;
1468 spin_unlock(&swap_lock
);
1469 mutex_unlock(&swapon_mutex
);
1471 inode
= mapping
->host
;
1472 if (S_ISBLK(inode
->i_mode
)) {
1473 struct block_device
*bdev
= I_BDEV(inode
);
1474 set_blocksize(bdev
, p
->old_block_size
);
1477 mutex_lock(&inode
->i_mutex
);
1478 inode
->i_flags
&= ~S_SWAPFILE
;
1479 mutex_unlock(&inode
->i_mutex
);
1481 filp_close(swap_file
, NULL
);
1485 filp_close(victim
, NULL
);
1490 #ifdef CONFIG_PROC_FS
1492 static void *swap_start(struct seq_file
*swap
, loff_t
*pos
)
1494 struct swap_info_struct
*ptr
= swap_info
;
1498 mutex_lock(&swapon_mutex
);
1501 return SEQ_START_TOKEN
;
1503 for (i
= 0; i
< nr_swapfiles
; i
++, ptr
++) {
1504 if (!(ptr
->flags
& SWP_USED
) || !ptr
->swap_map
)
1513 static void *swap_next(struct seq_file
*swap
, void *v
, loff_t
*pos
)
1515 struct swap_info_struct
*ptr
;
1516 struct swap_info_struct
*endptr
= swap_info
+ nr_swapfiles
;
1518 if (v
== SEQ_START_TOKEN
)
1525 for (; ptr
< endptr
; ptr
++) {
1526 if (!(ptr
->flags
& SWP_USED
) || !ptr
->swap_map
)
1535 static void swap_stop(struct seq_file
*swap
, void *v
)
1537 mutex_unlock(&swapon_mutex
);
1540 static int swap_show(struct seq_file
*swap
, void *v
)
1542 struct swap_info_struct
*ptr
= v
;
1546 if (ptr
== SEQ_START_TOKEN
) {
1547 seq_puts(swap
,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1551 file
= ptr
->swap_file
;
1552 len
= seq_path(swap
, &file
->f_path
, " \t\n\\");
1553 seq_printf(swap
, "%*s%s\t%u\t%u\t%d\n",
1554 len
< 40 ? 40 - len
: 1, " ",
1555 S_ISBLK(file
->f_path
.dentry
->d_inode
->i_mode
) ?
1556 "partition" : "file\t",
1557 ptr
->pages
<< (PAGE_SHIFT
- 10),
1558 ptr
->inuse_pages
<< (PAGE_SHIFT
- 10),
1563 static const struct seq_operations swaps_op
= {
1564 .start
= swap_start
,
1570 static int swaps_open(struct inode
*inode
, struct file
*file
)
1572 return seq_open(file
, &swaps_op
);
1575 static const struct file_operations proc_swaps_operations
= {
1578 .llseek
= seq_lseek
,
1579 .release
= seq_release
,
1582 static int __init
procswaps_init(void)
1584 proc_create("swaps", 0, NULL
, &proc_swaps_operations
);
1587 __initcall(procswaps_init
);
1588 #endif /* CONFIG_PROC_FS */
1590 #ifdef MAX_SWAPFILES_CHECK
1591 static int __init
max_swapfiles_check(void)
1593 MAX_SWAPFILES_CHECK();
1596 late_initcall(max_swapfiles_check
);
1600 * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
1602 * The swapon system call
1604 asmlinkage
long sys_swapon(const char __user
* specialfile
, int swap_flags
)
1606 struct swap_info_struct
* p
;
1608 struct block_device
*bdev
= NULL
;
1609 struct file
*swap_file
= NULL
;
1610 struct address_space
*mapping
;
1614 union swap_header
*swap_header
= NULL
;
1615 unsigned int nr_good_pages
= 0;
1618 unsigned long maxpages
= 1;
1619 unsigned long swapfilepages
;
1620 unsigned short *swap_map
= NULL
;
1621 struct page
*page
= NULL
;
1622 struct inode
*inode
= NULL
;
1625 if (!capable(CAP_SYS_ADMIN
))
1627 spin_lock(&swap_lock
);
1629 for (type
= 0 ; type
< nr_swapfiles
; type
++,p
++)
1630 if (!(p
->flags
& SWP_USED
))
1633 if (type
>= MAX_SWAPFILES
) {
1634 spin_unlock(&swap_lock
);
1637 if (type
>= nr_swapfiles
)
1638 nr_swapfiles
= type
+1;
1639 memset(p
, 0, sizeof(*p
));
1640 INIT_LIST_HEAD(&p
->extent_list
);
1641 p
->flags
= SWP_USED
;
1643 spin_unlock(&swap_lock
);
1644 name
= getname(specialfile
);
1645 error
= PTR_ERR(name
);
1650 swap_file
= filp_open(name
, O_RDWR
|O_LARGEFILE
, 0);
1651 error
= PTR_ERR(swap_file
);
1652 if (IS_ERR(swap_file
)) {
1657 p
->swap_file
= swap_file
;
1658 mapping
= swap_file
->f_mapping
;
1659 inode
= mapping
->host
;
1662 for (i
= 0; i
< nr_swapfiles
; i
++) {
1663 struct swap_info_struct
*q
= &swap_info
[i
];
1665 if (i
== type
|| !q
->swap_file
)
1667 if (mapping
== q
->swap_file
->f_mapping
)
1672 if (S_ISBLK(inode
->i_mode
)) {
1673 bdev
= I_BDEV(inode
);
1674 error
= bd_claim(bdev
, sys_swapon
);
1680 p
->old_block_size
= block_size(bdev
);
1681 error
= set_blocksize(bdev
, PAGE_SIZE
);
1685 } else if (S_ISREG(inode
->i_mode
)) {
1686 p
->bdev
= inode
->i_sb
->s_bdev
;
1687 mutex_lock(&inode
->i_mutex
);
1689 if (IS_SWAPFILE(inode
)) {
1697 swapfilepages
= i_size_read(inode
) >> PAGE_SHIFT
;
1700 * Read the swap header.
1702 if (!mapping
->a_ops
->readpage
) {
1706 page
= read_mapping_page(mapping
, 0, swap_file
);
1708 error
= PTR_ERR(page
);
1711 swap_header
= kmap(page
);
1713 if (memcmp("SWAPSPACE2", swap_header
->magic
.magic
, 10)) {
1714 printk(KERN_ERR
"Unable to find swap-space signature\n");
1719 /* swap partition endianess hack... */
1720 if (swab32(swap_header
->info
.version
) == 1) {
1721 swab32s(&swap_header
->info
.version
);
1722 swab32s(&swap_header
->info
.last_page
);
1723 swab32s(&swap_header
->info
.nr_badpages
);
1724 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++)
1725 swab32s(&swap_header
->info
.badpages
[i
]);
1727 /* Check the swap header's sub-version */
1728 if (swap_header
->info
.version
!= 1) {
1730 "Unable to handle swap header version %d\n",
1731 swap_header
->info
.version
);
1737 p
->cluster_next
= 1;
1740 * Find out how many pages are allowed for a single swap
1741 * device. There are two limiting factors: 1) the number of
1742 * bits for the swap offset in the swp_entry_t type and
1743 * 2) the number of bits in the a swap pte as defined by
1744 * the different architectures. In order to find the
1745 * largest possible bit mask a swap entry with swap type 0
1746 * and swap offset ~0UL is created, encoded to a swap pte,
1747 * decoded to a swp_entry_t again and finally the swap
1748 * offset is extracted. This will mask all the bits from
1749 * the initial ~0UL mask that can't be encoded in either
1750 * the swp_entry_t or the architecture definition of a
1753 maxpages
= swp_offset(pte_to_swp_entry(
1754 swp_entry_to_pte(swp_entry(0, ~0UL)))) - 1;
1755 if (maxpages
> swap_header
->info
.last_page
)
1756 maxpages
= swap_header
->info
.last_page
;
1757 p
->highest_bit
= maxpages
- 1;
1762 if (swapfilepages
&& maxpages
> swapfilepages
) {
1764 "Swap area shorter than signature indicates\n");
1767 if (swap_header
->info
.nr_badpages
&& S_ISREG(inode
->i_mode
))
1769 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
1772 /* OK, set up the swap map and apply the bad block list */
1773 swap_map
= vmalloc(maxpages
* sizeof(short));
1779 memset(swap_map
, 0, maxpages
* sizeof(short));
1780 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++) {
1781 int page_nr
= swap_header
->info
.badpages
[i
];
1782 if (page_nr
<= 0 || page_nr
>= swap_header
->info
.last_page
) {
1786 swap_map
[page_nr
] = SWAP_MAP_BAD
;
1788 nr_good_pages
= swap_header
->info
.last_page
-
1789 swap_header
->info
.nr_badpages
-
1790 1 /* header page */;
1792 if (nr_good_pages
) {
1793 swap_map
[0] = SWAP_MAP_BAD
;
1795 p
->pages
= nr_good_pages
;
1796 nr_extents
= setup_swap_extents(p
, &span
);
1797 if (nr_extents
< 0) {
1801 nr_good_pages
= p
->pages
;
1803 if (!nr_good_pages
) {
1804 printk(KERN_WARNING
"Empty swap-file\n");
1809 if (discard_swap(p
) == 0)
1810 p
->flags
|= SWP_DISCARDABLE
;
1812 mutex_lock(&swapon_mutex
);
1813 spin_lock(&swap_lock
);
1814 if (swap_flags
& SWAP_FLAG_PREFER
)
1816 (swap_flags
& SWAP_FLAG_PRIO_MASK
) >> SWAP_FLAG_PRIO_SHIFT
;
1818 p
->prio
= --least_priority
;
1819 p
->swap_map
= swap_map
;
1820 p
->flags
|= SWP_WRITEOK
;
1821 nr_swap_pages
+= nr_good_pages
;
1822 total_swap_pages
+= nr_good_pages
;
1824 printk(KERN_INFO
"Adding %uk swap on %s. "
1825 "Priority:%d extents:%d across:%lluk%s\n",
1826 nr_good_pages
<<(PAGE_SHIFT
-10), name
, p
->prio
,
1827 nr_extents
, (unsigned long long)span
<<(PAGE_SHIFT
-10),
1828 (p
->flags
& SWP_DISCARDABLE
) ? " D" : "");
1830 /* insert swap space into swap_list: */
1832 for (i
= swap_list
.head
; i
>= 0; i
= swap_info
[i
].next
) {
1833 if (p
->prio
>= swap_info
[i
].prio
) {
1840 swap_list
.head
= swap_list
.next
= p
- swap_info
;
1842 swap_info
[prev
].next
= p
- swap_info
;
1844 spin_unlock(&swap_lock
);
1845 mutex_unlock(&swapon_mutex
);
1850 set_blocksize(bdev
, p
->old_block_size
);
1853 destroy_swap_extents(p
);
1855 spin_lock(&swap_lock
);
1856 p
->swap_file
= NULL
;
1858 spin_unlock(&swap_lock
);
1861 filp_close(swap_file
, NULL
);
1863 if (page
&& !IS_ERR(page
)) {
1865 page_cache_release(page
);
1871 inode
->i_flags
|= S_SWAPFILE
;
1872 mutex_unlock(&inode
->i_mutex
);
1877 void si_swapinfo(struct sysinfo
*val
)
1880 unsigned long nr_to_be_unused
= 0;
1882 spin_lock(&swap_lock
);
1883 for (i
= 0; i
< nr_swapfiles
; i
++) {
1884 if (!(swap_info
[i
].flags
& SWP_USED
) ||
1885 (swap_info
[i
].flags
& SWP_WRITEOK
))
1887 nr_to_be_unused
+= swap_info
[i
].inuse_pages
;
1889 val
->freeswap
= nr_swap_pages
+ nr_to_be_unused
;
1890 val
->totalswap
= total_swap_pages
+ nr_to_be_unused
;
1891 spin_unlock(&swap_lock
);
1895 * Verify that a swap entry is valid and increment its swap map count.
1897 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
1898 * "permanent", but will be reclaimed by the next swapoff.
1900 int swap_duplicate(swp_entry_t entry
)
1902 struct swap_info_struct
* p
;
1903 unsigned long offset
, type
;
1906 if (is_migration_entry(entry
))
1909 type
= swp_type(entry
);
1910 if (type
>= nr_swapfiles
)
1912 p
= type
+ swap_info
;
1913 offset
= swp_offset(entry
);
1915 spin_lock(&swap_lock
);
1916 if (offset
< p
->max
&& p
->swap_map
[offset
]) {
1917 if (p
->swap_map
[offset
] < SWAP_MAP_MAX
- 1) {
1918 p
->swap_map
[offset
]++;
1920 } else if (p
->swap_map
[offset
] <= SWAP_MAP_MAX
) {
1921 if (swap_overflow
++ < 5)
1922 printk(KERN_WARNING
"swap_dup: swap entry overflow\n");
1923 p
->swap_map
[offset
] = SWAP_MAP_MAX
;
1927 spin_unlock(&swap_lock
);
1932 printk(KERN_ERR
"swap_dup: %s%08lx\n", Bad_file
, entry
.val
);
1936 struct swap_info_struct
*
1937 get_swap_info_struct(unsigned type
)
1939 return &swap_info
[type
];
1943 * swap_lock prevents swap_map being freed. Don't grab an extra
1944 * reference on the swaphandle, it doesn't matter if it becomes unused.
1946 int valid_swaphandles(swp_entry_t entry
, unsigned long *offset
)
1948 struct swap_info_struct
*si
;
1949 int our_page_cluster
= page_cluster
;
1950 pgoff_t target
, toff
;
1954 if (!our_page_cluster
) /* no readahead */
1957 si
= &swap_info
[swp_type(entry
)];
1958 target
= swp_offset(entry
);
1959 base
= (target
>> our_page_cluster
) << our_page_cluster
;
1960 end
= base
+ (1 << our_page_cluster
);
1961 if (!base
) /* first page is swap header */
1964 spin_lock(&swap_lock
);
1965 if (end
> si
->max
) /* don't go beyond end of map */
1968 /* Count contiguous allocated slots above our target */
1969 for (toff
= target
; ++toff
< end
; nr_pages
++) {
1970 /* Don't read in free or bad pages */
1971 if (!si
->swap_map
[toff
])
1973 if (si
->swap_map
[toff
] == SWAP_MAP_BAD
)
1976 /* Count contiguous allocated slots below our target */
1977 for (toff
= target
; --toff
>= base
; nr_pages
++) {
1978 /* Don't read in free or bad pages */
1979 if (!si
->swap_map
[toff
])
1981 if (si
->swap_map
[toff
] == SWAP_MAP_BAD
)
1984 spin_unlock(&swap_lock
);
1987 * Indicate starting offset, and return number of pages to get:
1988 * if only 1, say 0, since there's then no readahead to be done.
1991 return nr_pages
? ++nr_pages
: 0;