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>
37 static DEFINE_SPINLOCK(swap_lock
);
38 static unsigned int nr_swapfiles
;
40 long total_swap_pages
;
41 static int swap_overflow
;
42 static int least_priority
;
44 static const char Bad_file
[] = "Bad swap file entry ";
45 static const char Unused_file
[] = "Unused swap file entry ";
46 static const char Bad_offset
[] = "Bad swap offset entry ";
47 static const char Unused_offset
[] = "Unused swap offset entry ";
49 static struct swap_list_t swap_list
= {-1, -1};
51 static struct swap_info_struct swap_info
[MAX_SWAPFILES
];
53 static DEFINE_MUTEX(swapon_mutex
);
56 * We need this because the bdev->unplug_fn can sleep and we cannot
57 * hold swap_lock while calling the unplug_fn. And swap_lock
58 * cannot be turned into a mutex.
60 static DECLARE_RWSEM(swap_unplug_sem
);
62 void swap_unplug_io_fn(struct backing_dev_info
*unused_bdi
, struct page
*page
)
66 down_read(&swap_unplug_sem
);
67 entry
.val
= page_private(page
);
68 if (PageSwapCache(page
)) {
69 struct block_device
*bdev
= swap_info
[swp_type(entry
)].bdev
;
70 struct backing_dev_info
*bdi
;
73 * If the page is removed from swapcache from under us (with a
74 * racy try_to_unuse/swapoff) we need an additional reference
75 * count to avoid reading garbage from page_private(page) above.
76 * If the WARN_ON triggers during a swapoff it maybe the race
77 * condition and it's harmless. However if it triggers without
78 * swapoff it signals a problem.
80 WARN_ON(page_count(page
) <= 1);
82 bdi
= bdev
->bd_inode
->i_mapping
->backing_dev_info
;
83 blk_run_backing_dev(bdi
, page
);
85 up_read(&swap_unplug_sem
);
89 * swapon tell device that all the old swap contents can be discarded,
90 * to allow the swap device to optimize its wear-levelling.
92 static int discard_swap(struct swap_info_struct
*si
)
94 struct swap_extent
*se
;
97 list_for_each_entry(se
, &si
->extent_list
, list
) {
98 sector_t start_block
= se
->start_block
<< (PAGE_SHIFT
- 9);
99 pgoff_t nr_blocks
= se
->nr_pages
<< (PAGE_SHIFT
- 9);
101 if (se
->start_page
== 0) {
102 /* Do not discard the swap header page! */
103 start_block
+= 1 << (PAGE_SHIFT
- 9);
104 nr_blocks
-= 1 << (PAGE_SHIFT
- 9);
109 err
= blkdev_issue_discard(si
->bdev
, start_block
,
110 nr_blocks
, GFP_KERNEL
);
116 return err
; /* That will often be -EOPNOTSUPP */
120 * swap allocation tell device that a cluster of swap can now be discarded,
121 * to allow the swap device to optimize its wear-levelling.
123 static void discard_swap_cluster(struct swap_info_struct
*si
,
124 pgoff_t start_page
, pgoff_t nr_pages
)
126 struct swap_extent
*se
= si
->curr_swap_extent
;
127 int found_extent
= 0;
130 struct list_head
*lh
;
132 if (se
->start_page
<= start_page
&&
133 start_page
< se
->start_page
+ se
->nr_pages
) {
134 pgoff_t offset
= start_page
- se
->start_page
;
135 sector_t start_block
= se
->start_block
+ offset
;
136 pgoff_t nr_blocks
= se
->nr_pages
- offset
;
138 if (nr_blocks
> nr_pages
)
139 nr_blocks
= nr_pages
;
140 start_page
+= nr_blocks
;
141 nr_pages
-= nr_blocks
;
144 si
->curr_swap_extent
= se
;
146 start_block
<<= PAGE_SHIFT
- 9;
147 nr_blocks
<<= PAGE_SHIFT
- 9;
148 if (blkdev_issue_discard(si
->bdev
, start_block
,
149 nr_blocks
, GFP_NOIO
))
154 if (lh
== &si
->extent_list
)
156 se
= list_entry(lh
, struct swap_extent
, list
);
160 static int wait_for_discard(void *word
)
166 #define SWAPFILE_CLUSTER 256
167 #define LATENCY_LIMIT 256
169 static inline unsigned long scan_swap_map(struct swap_info_struct
*si
)
171 unsigned long offset
;
172 unsigned long last_in_cluster
= 0;
173 int latency_ration
= LATENCY_LIMIT
;
174 int found_free_cluster
= 0;
177 * We try to cluster swap pages by allocating them sequentially
178 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this
179 * way, however, we resort to first-free allocation, starting
180 * a new cluster. This prevents us from scattering swap pages
181 * all over the entire swap partition, so that we reduce
182 * overall disk seek times between swap pages. -- sct
183 * But we do now try to find an empty cluster. -Andrea
186 si
->flags
+= SWP_SCANNING
;
187 offset
= si
->cluster_next
;
189 if (unlikely(!si
->cluster_nr
--)) {
190 if (si
->pages
- si
->inuse_pages
< SWAPFILE_CLUSTER
) {
191 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
194 if (si
->flags
& SWP_DISCARDABLE
) {
196 * Start range check on racing allocations, in case
197 * they overlap the cluster we eventually decide on
198 * (we scan without swap_lock to allow preemption).
199 * It's hardly conceivable that cluster_nr could be
200 * wrapped during our scan, but don't depend on it.
202 if (si
->lowest_alloc
)
204 si
->lowest_alloc
= si
->max
;
205 si
->highest_alloc
= 0;
207 spin_unlock(&swap_lock
);
209 offset
= si
->lowest_bit
;
210 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
- 1;
212 /* Locate the first empty (unaligned) cluster */
213 for (; last_in_cluster
<= si
->highest_bit
; offset
++) {
214 if (si
->swap_map
[offset
])
215 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
;
216 else if (offset
== last_in_cluster
) {
217 spin_lock(&swap_lock
);
218 offset
-= SWAPFILE_CLUSTER
- 1;
219 si
->cluster_next
= offset
;
220 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
221 found_free_cluster
= 1;
224 if (unlikely(--latency_ration
< 0)) {
226 latency_ration
= LATENCY_LIMIT
;
230 offset
= si
->lowest_bit
;
231 spin_lock(&swap_lock
);
232 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
233 si
->lowest_alloc
= 0;
237 if (!(si
->flags
& SWP_WRITEOK
))
239 if (!si
->highest_bit
)
241 if (offset
> si
->highest_bit
)
242 offset
= si
->lowest_bit
;
243 if (si
->swap_map
[offset
])
246 if (offset
== si
->lowest_bit
)
248 if (offset
== si
->highest_bit
)
251 if (si
->inuse_pages
== si
->pages
) {
252 si
->lowest_bit
= si
->max
;
255 si
->swap_map
[offset
] = 1;
256 si
->cluster_next
= offset
+ 1;
257 si
->flags
-= SWP_SCANNING
;
259 if (si
->lowest_alloc
) {
261 * Only set when SWP_DISCARDABLE, and there's a scan
262 * for a free cluster in progress or just completed.
264 if (found_free_cluster
) {
266 * To optimize wear-levelling, discard the
267 * old data of the cluster, taking care not to
268 * discard any of its pages that have already
269 * been allocated by racing tasks (offset has
270 * already stepped over any at the beginning).
272 if (offset
< si
->highest_alloc
&&
273 si
->lowest_alloc
<= last_in_cluster
)
274 last_in_cluster
= si
->lowest_alloc
- 1;
275 si
->flags
|= SWP_DISCARDING
;
276 spin_unlock(&swap_lock
);
278 if (offset
< last_in_cluster
)
279 discard_swap_cluster(si
, offset
,
280 last_in_cluster
- offset
+ 1);
282 spin_lock(&swap_lock
);
283 si
->lowest_alloc
= 0;
284 si
->flags
&= ~SWP_DISCARDING
;
286 smp_mb(); /* wake_up_bit advises this */
287 wake_up_bit(&si
->flags
, ilog2(SWP_DISCARDING
));
289 } else if (si
->flags
& SWP_DISCARDING
) {
291 * Delay using pages allocated by racing tasks
292 * until the whole discard has been issued. We
293 * could defer that delay until swap_writepage,
294 * but it's easier to keep this self-contained.
296 spin_unlock(&swap_lock
);
297 wait_on_bit(&si
->flags
, ilog2(SWP_DISCARDING
),
298 wait_for_discard
, TASK_UNINTERRUPTIBLE
);
299 spin_lock(&swap_lock
);
302 * Note pages allocated by racing tasks while
303 * scan for a free cluster is in progress, so
304 * that its final discard can exclude them.
306 if (offset
< si
->lowest_alloc
)
307 si
->lowest_alloc
= offset
;
308 if (offset
> si
->highest_alloc
)
309 si
->highest_alloc
= offset
;
315 spin_unlock(&swap_lock
);
316 while (++offset
<= si
->highest_bit
) {
317 if (!si
->swap_map
[offset
]) {
318 spin_lock(&swap_lock
);
321 if (unlikely(--latency_ration
< 0)) {
323 latency_ration
= LATENCY_LIMIT
;
326 spin_lock(&swap_lock
);
330 si
->flags
-= SWP_SCANNING
;
334 swp_entry_t
get_swap_page(void)
336 struct swap_info_struct
*si
;
341 spin_lock(&swap_lock
);
342 if (nr_swap_pages
<= 0)
346 for (type
= swap_list
.next
; type
>= 0 && wrapped
< 2; type
= next
) {
347 si
= swap_info
+ type
;
350 (!wrapped
&& si
->prio
!= swap_info
[next
].prio
)) {
351 next
= swap_list
.head
;
355 if (!si
->highest_bit
)
357 if (!(si
->flags
& SWP_WRITEOK
))
360 swap_list
.next
= next
;
361 offset
= scan_swap_map(si
);
363 spin_unlock(&swap_lock
);
364 return swp_entry(type
, offset
);
366 next
= swap_list
.next
;
371 spin_unlock(&swap_lock
);
372 return (swp_entry_t
) {0};
375 swp_entry_t
get_swap_page_of_type(int type
)
377 struct swap_info_struct
*si
;
380 spin_lock(&swap_lock
);
381 si
= swap_info
+ type
;
382 if (si
->flags
& SWP_WRITEOK
) {
384 offset
= scan_swap_map(si
);
386 spin_unlock(&swap_lock
);
387 return swp_entry(type
, offset
);
391 spin_unlock(&swap_lock
);
392 return (swp_entry_t
) {0};
395 static struct swap_info_struct
* swap_info_get(swp_entry_t entry
)
397 struct swap_info_struct
* p
;
398 unsigned long offset
, type
;
402 type
= swp_type(entry
);
403 if (type
>= nr_swapfiles
)
405 p
= & swap_info
[type
];
406 if (!(p
->flags
& SWP_USED
))
408 offset
= swp_offset(entry
);
409 if (offset
>= p
->max
)
411 if (!p
->swap_map
[offset
])
413 spin_lock(&swap_lock
);
417 printk(KERN_ERR
"swap_free: %s%08lx\n", Unused_offset
, entry
.val
);
420 printk(KERN_ERR
"swap_free: %s%08lx\n", Bad_offset
, entry
.val
);
423 printk(KERN_ERR
"swap_free: %s%08lx\n", Unused_file
, entry
.val
);
426 printk(KERN_ERR
"swap_free: %s%08lx\n", Bad_file
, entry
.val
);
431 static int swap_entry_free(struct swap_info_struct
*p
, unsigned long offset
)
433 int count
= p
->swap_map
[offset
];
435 if (count
< SWAP_MAP_MAX
) {
437 p
->swap_map
[offset
] = count
;
439 if (offset
< p
->lowest_bit
)
440 p
->lowest_bit
= offset
;
441 if (offset
> p
->highest_bit
)
442 p
->highest_bit
= offset
;
443 if (p
->prio
> swap_info
[swap_list
.next
].prio
)
444 swap_list
.next
= p
- swap_info
;
453 * Caller has made sure that the swapdevice corresponding to entry
454 * is still around or has not been recycled.
456 void swap_free(swp_entry_t entry
)
458 struct swap_info_struct
* p
;
460 p
= swap_info_get(entry
);
462 swap_entry_free(p
, swp_offset(entry
));
463 spin_unlock(&swap_lock
);
468 * How many references to page are currently swapped out?
470 static inline int page_swapcount(struct page
*page
)
473 struct swap_info_struct
*p
;
476 entry
.val
= page_private(page
);
477 p
= swap_info_get(entry
);
479 /* Subtract the 1 for the swap cache itself */
480 count
= p
->swap_map
[swp_offset(entry
)] - 1;
481 spin_unlock(&swap_lock
);
487 * We can write to an anon page without COW if there are no other references
488 * to it. And as a side-effect, free up its swap: because the old content
489 * on disk will never be read, and seeking back there to write new content
490 * later would only waste time away from clustering.
492 int reuse_swap_page(struct page
*page
)
496 VM_BUG_ON(!PageLocked(page
));
497 count
= page_mapcount(page
);
498 if (count
<= 1 && PageSwapCache(page
)) {
499 count
+= page_swapcount(page
);
500 if (count
== 1 && !PageWriteback(page
)) {
501 delete_from_swap_cache(page
);
509 * If swap is getting full, or if there are no more mappings of this page,
510 * then try_to_free_swap is called to free its swap space.
512 int try_to_free_swap(struct page
*page
)
514 VM_BUG_ON(!PageLocked(page
));
516 if (!PageSwapCache(page
))
518 if (PageWriteback(page
))
520 if (page_swapcount(page
))
523 delete_from_swap_cache(page
);
529 * Free the swap entry like above, but also try to
530 * free the page cache entry if it is the last user.
532 void free_swap_and_cache(swp_entry_t entry
)
534 struct swap_info_struct
* p
;
535 struct page
*page
= NULL
;
537 if (is_migration_entry(entry
))
540 p
= swap_info_get(entry
);
542 if (swap_entry_free(p
, swp_offset(entry
)) == 1) {
543 page
= find_get_page(&swapper_space
, entry
.val
);
544 if (page
&& !trylock_page(page
)) {
545 page_cache_release(page
);
549 spin_unlock(&swap_lock
);
553 * Not mapped elsewhere, or swap space full? Free it!
554 * Also recheck PageSwapCache now page is locked (above).
556 if (PageSwapCache(page
) && !PageWriteback(page
) &&
557 (!page_mapped(page
) || vm_swap_full())) {
558 delete_from_swap_cache(page
);
562 page_cache_release(page
);
566 #ifdef CONFIG_HIBERNATION
568 * Find the swap type that corresponds to given device (if any).
570 * @offset - number of the PAGE_SIZE-sized block of the device, starting
571 * from 0, in which the swap header is expected to be located.
573 * This is needed for the suspend to disk (aka swsusp).
575 int swap_type_of(dev_t device
, sector_t offset
, struct block_device
**bdev_p
)
577 struct block_device
*bdev
= NULL
;
581 bdev
= bdget(device
);
583 spin_lock(&swap_lock
);
584 for (i
= 0; i
< nr_swapfiles
; i
++) {
585 struct swap_info_struct
*sis
= swap_info
+ i
;
587 if (!(sis
->flags
& SWP_WRITEOK
))
594 spin_unlock(&swap_lock
);
597 if (bdev
== sis
->bdev
) {
598 struct swap_extent
*se
;
600 se
= list_entry(sis
->extent_list
.next
,
601 struct swap_extent
, list
);
602 if (se
->start_block
== offset
) {
606 spin_unlock(&swap_lock
);
612 spin_unlock(&swap_lock
);
620 * Return either the total number of swap pages of given type, or the number
621 * of free pages of that type (depending on @free)
623 * This is needed for software suspend
625 unsigned int count_swap_pages(int type
, int free
)
629 if (type
< nr_swapfiles
) {
630 spin_lock(&swap_lock
);
631 if (swap_info
[type
].flags
& SWP_WRITEOK
) {
632 n
= swap_info
[type
].pages
;
634 n
-= swap_info
[type
].inuse_pages
;
636 spin_unlock(&swap_lock
);
643 * No need to decide whether this PTE shares the swap entry with others,
644 * just let do_wp_page work it out if a write is requested later - to
645 * force COW, vm_page_prot omits write permission from any private vma.
647 static int unuse_pte(struct vm_area_struct
*vma
, pmd_t
*pmd
,
648 unsigned long addr
, swp_entry_t entry
, struct page
*page
)
654 if (mem_cgroup_charge(page
, vma
->vm_mm
, GFP_KERNEL
))
657 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
658 if (unlikely(!pte_same(*pte
, swp_entry_to_pte(entry
)))) {
660 mem_cgroup_uncharge_page(page
);
665 inc_mm_counter(vma
->vm_mm
, anon_rss
);
667 set_pte_at(vma
->vm_mm
, addr
, pte
,
668 pte_mkold(mk_pte(page
, vma
->vm_page_prot
)));
669 page_add_anon_rmap(page
, vma
, addr
);
672 * Move the page to the active list so it is not
673 * immediately swapped out again after swapon.
677 pte_unmap_unlock(pte
, ptl
);
681 static int unuse_pte_range(struct vm_area_struct
*vma
, pmd_t
*pmd
,
682 unsigned long addr
, unsigned long end
,
683 swp_entry_t entry
, struct page
*page
)
685 pte_t swp_pte
= swp_entry_to_pte(entry
);
690 * We don't actually need pte lock while scanning for swp_pte: since
691 * we hold page lock and mmap_sem, swp_pte cannot be inserted into the
692 * page table while we're scanning; though it could get zapped, and on
693 * some architectures (e.g. x86_32 with PAE) we might catch a glimpse
694 * of unmatched parts which look like swp_pte, so unuse_pte must
695 * recheck under pte lock. Scanning without pte lock lets it be
696 * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE.
698 pte
= pte_offset_map(pmd
, addr
);
701 * swapoff spends a _lot_ of time in this loop!
702 * Test inline before going to call unuse_pte.
704 if (unlikely(pte_same(*pte
, swp_pte
))) {
706 ret
= unuse_pte(vma
, pmd
, addr
, entry
, page
);
709 pte
= pte_offset_map(pmd
, addr
);
711 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
717 static inline int unuse_pmd_range(struct vm_area_struct
*vma
, pud_t
*pud
,
718 unsigned long addr
, unsigned long end
,
719 swp_entry_t entry
, struct page
*page
)
725 pmd
= pmd_offset(pud
, addr
);
727 next
= pmd_addr_end(addr
, end
);
728 if (pmd_none_or_clear_bad(pmd
))
730 ret
= unuse_pte_range(vma
, pmd
, addr
, next
, entry
, page
);
733 } while (pmd
++, addr
= next
, addr
!= end
);
737 static inline int unuse_pud_range(struct vm_area_struct
*vma
, pgd_t
*pgd
,
738 unsigned long addr
, unsigned long end
,
739 swp_entry_t entry
, struct page
*page
)
745 pud
= pud_offset(pgd
, addr
);
747 next
= pud_addr_end(addr
, end
);
748 if (pud_none_or_clear_bad(pud
))
750 ret
= unuse_pmd_range(vma
, pud
, addr
, next
, entry
, page
);
753 } while (pud
++, addr
= next
, addr
!= end
);
757 static int unuse_vma(struct vm_area_struct
*vma
,
758 swp_entry_t entry
, struct page
*page
)
761 unsigned long addr
, end
, next
;
765 addr
= page_address_in_vma(page
, vma
);
769 end
= addr
+ PAGE_SIZE
;
771 addr
= vma
->vm_start
;
775 pgd
= pgd_offset(vma
->vm_mm
, addr
);
777 next
= pgd_addr_end(addr
, end
);
778 if (pgd_none_or_clear_bad(pgd
))
780 ret
= unuse_pud_range(vma
, pgd
, addr
, next
, entry
, page
);
783 } while (pgd
++, addr
= next
, addr
!= end
);
787 static int unuse_mm(struct mm_struct
*mm
,
788 swp_entry_t entry
, struct page
*page
)
790 struct vm_area_struct
*vma
;
793 if (!down_read_trylock(&mm
->mmap_sem
)) {
795 * Activate page so shrink_inactive_list is unlikely to unmap
796 * its ptes while lock is dropped, so swapoff can make progress.
800 down_read(&mm
->mmap_sem
);
803 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
804 if (vma
->anon_vma
&& (ret
= unuse_vma(vma
, entry
, page
)))
807 up_read(&mm
->mmap_sem
);
808 return (ret
< 0)? ret
: 0;
812 * Scan swap_map from current position to next entry still in use.
813 * Recycle to start on reaching the end, returning 0 when empty.
815 static unsigned int find_next_to_unuse(struct swap_info_struct
*si
,
818 unsigned int max
= si
->max
;
819 unsigned int i
= prev
;
823 * No need for swap_lock here: we're just looking
824 * for whether an entry is in use, not modifying it; false
825 * hits are okay, and sys_swapoff() has already prevented new
826 * allocations from this area (while holding swap_lock).
835 * No entries in use at top of swap_map,
836 * loop back to start and recheck there.
842 count
= si
->swap_map
[i
];
843 if (count
&& count
!= SWAP_MAP_BAD
)
850 * We completely avoid races by reading each swap page in advance,
851 * and then search for the process using it. All the necessary
852 * page table adjustments can then be made atomically.
854 static int try_to_unuse(unsigned int type
)
856 struct swap_info_struct
* si
= &swap_info
[type
];
857 struct mm_struct
*start_mm
;
858 unsigned short *swap_map
;
859 unsigned short swcount
;
864 int reset_overflow
= 0;
868 * When searching mms for an entry, a good strategy is to
869 * start at the first mm we freed the previous entry from
870 * (though actually we don't notice whether we or coincidence
871 * freed the entry). Initialize this start_mm with a hold.
873 * A simpler strategy would be to start at the last mm we
874 * freed the previous entry from; but that would take less
875 * advantage of mmlist ordering, which clusters forked mms
876 * together, child after parent. If we race with dup_mmap(), we
877 * prefer to resolve parent before child, lest we miss entries
878 * duplicated after we scanned child: using last mm would invert
879 * that. Though it's only a serious concern when an overflowed
880 * swap count is reset from SWAP_MAP_MAX, preventing a rescan.
883 atomic_inc(&init_mm
.mm_users
);
886 * Keep on scanning until all entries have gone. Usually,
887 * one pass through swap_map is enough, but not necessarily:
888 * there are races when an instance of an entry might be missed.
890 while ((i
= find_next_to_unuse(si
, i
)) != 0) {
891 if (signal_pending(current
)) {
897 * Get a page for the entry, using the existing swap
898 * cache page if there is one. Otherwise, get a clean
899 * page and read the swap into it.
901 swap_map
= &si
->swap_map
[i
];
902 entry
= swp_entry(type
, i
);
903 page
= read_swap_cache_async(entry
,
904 GFP_HIGHUSER_MOVABLE
, NULL
, 0);
907 * Either swap_duplicate() failed because entry
908 * has been freed independently, and will not be
909 * reused since sys_swapoff() already disabled
910 * allocation from here, or alloc_page() failed.
919 * Don't hold on to start_mm if it looks like exiting.
921 if (atomic_read(&start_mm
->mm_users
) == 1) {
924 atomic_inc(&init_mm
.mm_users
);
928 * Wait for and lock page. When do_swap_page races with
929 * try_to_unuse, do_swap_page can handle the fault much
930 * faster than try_to_unuse can locate the entry. This
931 * apparently redundant "wait_on_page_locked" lets try_to_unuse
932 * defer to do_swap_page in such a case - in some tests,
933 * do_swap_page and try_to_unuse repeatedly compete.
935 wait_on_page_locked(page
);
936 wait_on_page_writeback(page
);
938 wait_on_page_writeback(page
);
941 * Remove all references to entry.
942 * Whenever we reach init_mm, there's no address space
943 * to search, but use it as a reminder to search shmem.
948 if (start_mm
== &init_mm
)
949 shmem
= shmem_unuse(entry
, page
);
951 retval
= unuse_mm(start_mm
, entry
, page
);
954 int set_start_mm
= (*swap_map
>= swcount
);
955 struct list_head
*p
= &start_mm
->mmlist
;
956 struct mm_struct
*new_start_mm
= start_mm
;
957 struct mm_struct
*prev_mm
= start_mm
;
958 struct mm_struct
*mm
;
960 atomic_inc(&new_start_mm
->mm_users
);
961 atomic_inc(&prev_mm
->mm_users
);
962 spin_lock(&mmlist_lock
);
963 while (*swap_map
> 1 && !retval
&& !shmem
&&
964 (p
= p
->next
) != &start_mm
->mmlist
) {
965 mm
= list_entry(p
, struct mm_struct
, mmlist
);
966 if (!atomic_inc_not_zero(&mm
->mm_users
))
968 spin_unlock(&mmlist_lock
);
977 else if (mm
== &init_mm
) {
979 shmem
= shmem_unuse(entry
, page
);
981 retval
= unuse_mm(mm
, entry
, page
);
982 if (set_start_mm
&& *swap_map
< swcount
) {
984 atomic_inc(&mm
->mm_users
);
988 spin_lock(&mmlist_lock
);
990 spin_unlock(&mmlist_lock
);
993 start_mm
= new_start_mm
;
996 /* page has already been unlocked and released */
1004 page_cache_release(page
);
1009 * How could swap count reach 0x7fff when the maximum
1010 * pid is 0x7fff, and there's no way to repeat a swap
1011 * page within an mm (except in shmem, where it's the
1012 * shared object which takes the reference count)?
1013 * We believe SWAP_MAP_MAX cannot occur in Linux 2.4.
1015 * If that's wrong, then we should worry more about
1016 * exit_mmap() and do_munmap() cases described above:
1017 * we might be resetting SWAP_MAP_MAX too early here.
1018 * We know "Undead"s can happen, they're okay, so don't
1019 * report them; but do report if we reset SWAP_MAP_MAX.
1021 if (*swap_map
== SWAP_MAP_MAX
) {
1022 spin_lock(&swap_lock
);
1024 spin_unlock(&swap_lock
);
1029 * If a reference remains (rare), we would like to leave
1030 * the page in the swap cache; but try_to_unmap could
1031 * then re-duplicate the entry once we drop page lock,
1032 * so we might loop indefinitely; also, that page could
1033 * not be swapped out to other storage meanwhile. So:
1034 * delete from cache even if there's another reference,
1035 * after ensuring that the data has been saved to disk -
1036 * since if the reference remains (rarer), it will be
1037 * read from disk into another page. Splitting into two
1038 * pages would be incorrect if swap supported "shared
1039 * private" pages, but they are handled by tmpfs files.
1041 if ((*swap_map
> 1) && PageDirty(page
) && PageSwapCache(page
)) {
1042 struct writeback_control wbc
= {
1043 .sync_mode
= WB_SYNC_NONE
,
1046 swap_writepage(page
, &wbc
);
1048 wait_on_page_writeback(page
);
1052 * It is conceivable that a racing task removed this page from
1053 * swap cache just before we acquired the page lock at the top,
1054 * or while we dropped it in unuse_mm(). The page might even
1055 * be back in swap cache on another swap area: that we must not
1056 * delete, since it may not have been written out to swap yet.
1058 if (PageSwapCache(page
) &&
1059 likely(page_private(page
) == entry
.val
))
1060 delete_from_swap_cache(page
);
1063 * So we could skip searching mms once swap count went
1064 * to 1, we did not mark any present ptes as dirty: must
1065 * mark page dirty so shrink_page_list will preserve it.
1069 page_cache_release(page
);
1072 * Make sure that we aren't completely killing
1073 * interactive performance.
1079 if (reset_overflow
) {
1080 printk(KERN_WARNING
"swapoff: cleared swap entry overflow\n");
1087 * After a successful try_to_unuse, if no swap is now in use, we know
1088 * we can empty the mmlist. swap_lock must be held on entry and exit.
1089 * Note that mmlist_lock nests inside swap_lock, and an mm must be
1090 * added to the mmlist just after page_duplicate - before would be racy.
1092 static void drain_mmlist(void)
1094 struct list_head
*p
, *next
;
1097 for (i
= 0; i
< nr_swapfiles
; i
++)
1098 if (swap_info
[i
].inuse_pages
)
1100 spin_lock(&mmlist_lock
);
1101 list_for_each_safe(p
, next
, &init_mm
.mmlist
)
1103 spin_unlock(&mmlist_lock
);
1107 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
1108 * corresponds to page offset `offset'.
1110 sector_t
map_swap_page(struct swap_info_struct
*sis
, pgoff_t offset
)
1112 struct swap_extent
*se
= sis
->curr_swap_extent
;
1113 struct swap_extent
*start_se
= se
;
1116 struct list_head
*lh
;
1118 if (se
->start_page
<= offset
&&
1119 offset
< (se
->start_page
+ se
->nr_pages
)) {
1120 return se
->start_block
+ (offset
- se
->start_page
);
1123 if (lh
== &sis
->extent_list
)
1125 se
= list_entry(lh
, struct swap_extent
, list
);
1126 sis
->curr_swap_extent
= se
;
1127 BUG_ON(se
== start_se
); /* It *must* be present */
1131 #ifdef CONFIG_HIBERNATION
1133 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
1134 * corresponding to given index in swap_info (swap type).
1136 sector_t
swapdev_block(int swap_type
, pgoff_t offset
)
1138 struct swap_info_struct
*sis
;
1140 if (swap_type
>= nr_swapfiles
)
1143 sis
= swap_info
+ swap_type
;
1144 return (sis
->flags
& SWP_WRITEOK
) ? map_swap_page(sis
, offset
) : 0;
1146 #endif /* CONFIG_HIBERNATION */
1149 * Free all of a swapdev's extent information
1151 static void destroy_swap_extents(struct swap_info_struct
*sis
)
1153 while (!list_empty(&sis
->extent_list
)) {
1154 struct swap_extent
*se
;
1156 se
= list_entry(sis
->extent_list
.next
,
1157 struct swap_extent
, list
);
1158 list_del(&se
->list
);
1164 * Add a block range (and the corresponding page range) into this swapdev's
1165 * extent list. The extent list is kept sorted in page order.
1167 * This function rather assumes that it is called in ascending page order.
1170 add_swap_extent(struct swap_info_struct
*sis
, unsigned long start_page
,
1171 unsigned long nr_pages
, sector_t start_block
)
1173 struct swap_extent
*se
;
1174 struct swap_extent
*new_se
;
1175 struct list_head
*lh
;
1177 lh
= sis
->extent_list
.prev
; /* The highest page extent */
1178 if (lh
!= &sis
->extent_list
) {
1179 se
= list_entry(lh
, struct swap_extent
, list
);
1180 BUG_ON(se
->start_page
+ se
->nr_pages
!= start_page
);
1181 if (se
->start_block
+ se
->nr_pages
== start_block
) {
1183 se
->nr_pages
+= nr_pages
;
1189 * No merge. Insert a new extent, preserving ordering.
1191 new_se
= kmalloc(sizeof(*se
), GFP_KERNEL
);
1194 new_se
->start_page
= start_page
;
1195 new_se
->nr_pages
= nr_pages
;
1196 new_se
->start_block
= start_block
;
1198 list_add_tail(&new_se
->list
, &sis
->extent_list
);
1203 * A `swap extent' is a simple thing which maps a contiguous range of pages
1204 * onto a contiguous range of disk blocks. An ordered list of swap extents
1205 * is built at swapon time and is then used at swap_writepage/swap_readpage
1206 * time for locating where on disk a page belongs.
1208 * If the swapfile is an S_ISBLK block device, a single extent is installed.
1209 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
1210 * swap files identically.
1212 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
1213 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
1214 * swapfiles are handled *identically* after swapon time.
1216 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
1217 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
1218 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
1219 * requirements, they are simply tossed out - we will never use those blocks
1222 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
1223 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
1224 * which will scribble on the fs.
1226 * The amount of disk space which a single swap extent represents varies.
1227 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
1228 * extents in the list. To avoid much list walking, we cache the previous
1229 * search location in `curr_swap_extent', and start new searches from there.
1230 * This is extremely effective. The average number of iterations in
1231 * map_swap_page() has been measured at about 0.3 per page. - akpm.
1233 static int setup_swap_extents(struct swap_info_struct
*sis
, sector_t
*span
)
1235 struct inode
*inode
;
1236 unsigned blocks_per_page
;
1237 unsigned long page_no
;
1239 sector_t probe_block
;
1240 sector_t last_block
;
1241 sector_t lowest_block
= -1;
1242 sector_t highest_block
= 0;
1246 inode
= sis
->swap_file
->f_mapping
->host
;
1247 if (S_ISBLK(inode
->i_mode
)) {
1248 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
1253 blkbits
= inode
->i_blkbits
;
1254 blocks_per_page
= PAGE_SIZE
>> blkbits
;
1257 * Map all the blocks into the extent list. This code doesn't try
1262 last_block
= i_size_read(inode
) >> blkbits
;
1263 while ((probe_block
+ blocks_per_page
) <= last_block
&&
1264 page_no
< sis
->max
) {
1265 unsigned block_in_page
;
1266 sector_t first_block
;
1268 first_block
= bmap(inode
, probe_block
);
1269 if (first_block
== 0)
1273 * It must be PAGE_SIZE aligned on-disk
1275 if (first_block
& (blocks_per_page
- 1)) {
1280 for (block_in_page
= 1; block_in_page
< blocks_per_page
;
1284 block
= bmap(inode
, probe_block
+ block_in_page
);
1287 if (block
!= first_block
+ block_in_page
) {
1294 first_block
>>= (PAGE_SHIFT
- blkbits
);
1295 if (page_no
) { /* exclude the header page */
1296 if (first_block
< lowest_block
)
1297 lowest_block
= first_block
;
1298 if (first_block
> highest_block
)
1299 highest_block
= first_block
;
1303 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1305 ret
= add_swap_extent(sis
, page_no
, 1, first_block
);
1310 probe_block
+= blocks_per_page
;
1315 *span
= 1 + highest_block
- lowest_block
;
1317 page_no
= 1; /* force Empty message */
1319 sis
->pages
= page_no
- 1;
1320 sis
->highest_bit
= page_no
- 1;
1322 sis
->curr_swap_extent
= list_entry(sis
->extent_list
.prev
,
1323 struct swap_extent
, list
);
1326 printk(KERN_ERR
"swapon: swapfile has holes\n");
1332 #if 0 /* We don't need this yet */
1333 #include <linux/backing-dev.h>
1334 int page_queue_congested(struct page
*page
)
1336 struct backing_dev_info
*bdi
;
1338 VM_BUG_ON(!PageLocked(page
)); /* It pins the swap_info_struct */
1340 if (PageSwapCache(page
)) {
1341 swp_entry_t entry
= { .val
= page_private(page
) };
1342 struct swap_info_struct
*sis
;
1344 sis
= get_swap_info_struct(swp_type(entry
));
1345 bdi
= sis
->bdev
->bd_inode
->i_mapping
->backing_dev_info
;
1347 bdi
= page
->mapping
->backing_dev_info
;
1348 return bdi_write_congested(bdi
);
1352 asmlinkage
long sys_swapoff(const char __user
* specialfile
)
1354 struct swap_info_struct
* p
= NULL
;
1355 unsigned short *swap_map
;
1356 struct file
*swap_file
, *victim
;
1357 struct address_space
*mapping
;
1358 struct inode
*inode
;
1363 if (!capable(CAP_SYS_ADMIN
))
1366 pathname
= getname(specialfile
);
1367 err
= PTR_ERR(pathname
);
1368 if (IS_ERR(pathname
))
1371 victim
= filp_open(pathname
, O_RDWR
|O_LARGEFILE
, 0);
1373 err
= PTR_ERR(victim
);
1377 mapping
= victim
->f_mapping
;
1379 spin_lock(&swap_lock
);
1380 for (type
= swap_list
.head
; type
>= 0; type
= swap_info
[type
].next
) {
1381 p
= swap_info
+ type
;
1382 if (p
->flags
& SWP_WRITEOK
) {
1383 if (p
->swap_file
->f_mapping
== mapping
)
1390 spin_unlock(&swap_lock
);
1393 if (!security_vm_enough_memory(p
->pages
))
1394 vm_unacct_memory(p
->pages
);
1397 spin_unlock(&swap_lock
);
1401 swap_list
.head
= p
->next
;
1403 swap_info
[prev
].next
= p
->next
;
1405 if (type
== swap_list
.next
) {
1406 /* just pick something that's safe... */
1407 swap_list
.next
= swap_list
.head
;
1410 for (i
= p
->next
; i
>= 0; i
= swap_info
[i
].next
)
1411 swap_info
[i
].prio
= p
->prio
--;
1414 nr_swap_pages
-= p
->pages
;
1415 total_swap_pages
-= p
->pages
;
1416 p
->flags
&= ~SWP_WRITEOK
;
1417 spin_unlock(&swap_lock
);
1419 current
->flags
|= PF_SWAPOFF
;
1420 err
= try_to_unuse(type
);
1421 current
->flags
&= ~PF_SWAPOFF
;
1424 /* re-insert swap space back into swap_list */
1425 spin_lock(&swap_lock
);
1427 p
->prio
= --least_priority
;
1429 for (i
= swap_list
.head
; i
>= 0; i
= swap_info
[i
].next
) {
1430 if (p
->prio
>= swap_info
[i
].prio
)
1436 swap_list
.head
= swap_list
.next
= p
- swap_info
;
1438 swap_info
[prev
].next
= p
- swap_info
;
1439 nr_swap_pages
+= p
->pages
;
1440 total_swap_pages
+= p
->pages
;
1441 p
->flags
|= SWP_WRITEOK
;
1442 spin_unlock(&swap_lock
);
1446 /* wait for any unplug function to finish */
1447 down_write(&swap_unplug_sem
);
1448 up_write(&swap_unplug_sem
);
1450 destroy_swap_extents(p
);
1451 mutex_lock(&swapon_mutex
);
1452 spin_lock(&swap_lock
);
1455 /* wait for anyone still in scan_swap_map */
1456 p
->highest_bit
= 0; /* cuts scans short */
1457 while (p
->flags
>= SWP_SCANNING
) {
1458 spin_unlock(&swap_lock
);
1459 schedule_timeout_uninterruptible(1);
1460 spin_lock(&swap_lock
);
1463 swap_file
= p
->swap_file
;
1464 p
->swap_file
= NULL
;
1466 swap_map
= p
->swap_map
;
1469 spin_unlock(&swap_lock
);
1470 mutex_unlock(&swapon_mutex
);
1472 inode
= mapping
->host
;
1473 if (S_ISBLK(inode
->i_mode
)) {
1474 struct block_device
*bdev
= I_BDEV(inode
);
1475 set_blocksize(bdev
, p
->old_block_size
);
1478 mutex_lock(&inode
->i_mutex
);
1479 inode
->i_flags
&= ~S_SWAPFILE
;
1480 mutex_unlock(&inode
->i_mutex
);
1482 filp_close(swap_file
, NULL
);
1486 filp_close(victim
, NULL
);
1491 #ifdef CONFIG_PROC_FS
1493 static void *swap_start(struct seq_file
*swap
, loff_t
*pos
)
1495 struct swap_info_struct
*ptr
= swap_info
;
1499 mutex_lock(&swapon_mutex
);
1502 return SEQ_START_TOKEN
;
1504 for (i
= 0; i
< nr_swapfiles
; i
++, ptr
++) {
1505 if (!(ptr
->flags
& SWP_USED
) || !ptr
->swap_map
)
1514 static void *swap_next(struct seq_file
*swap
, void *v
, loff_t
*pos
)
1516 struct swap_info_struct
*ptr
;
1517 struct swap_info_struct
*endptr
= swap_info
+ nr_swapfiles
;
1519 if (v
== SEQ_START_TOKEN
)
1526 for (; ptr
< endptr
; ptr
++) {
1527 if (!(ptr
->flags
& SWP_USED
) || !ptr
->swap_map
)
1536 static void swap_stop(struct seq_file
*swap
, void *v
)
1538 mutex_unlock(&swapon_mutex
);
1541 static int swap_show(struct seq_file
*swap
, void *v
)
1543 struct swap_info_struct
*ptr
= v
;
1547 if (ptr
== SEQ_START_TOKEN
) {
1548 seq_puts(swap
,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1552 file
= ptr
->swap_file
;
1553 len
= seq_path(swap
, &file
->f_path
, " \t\n\\");
1554 seq_printf(swap
, "%*s%s\t%u\t%u\t%d\n",
1555 len
< 40 ? 40 - len
: 1, " ",
1556 S_ISBLK(file
->f_path
.dentry
->d_inode
->i_mode
) ?
1557 "partition" : "file\t",
1558 ptr
->pages
<< (PAGE_SHIFT
- 10),
1559 ptr
->inuse_pages
<< (PAGE_SHIFT
- 10),
1564 static const struct seq_operations swaps_op
= {
1565 .start
= swap_start
,
1571 static int swaps_open(struct inode
*inode
, struct file
*file
)
1573 return seq_open(file
, &swaps_op
);
1576 static const struct file_operations proc_swaps_operations
= {
1579 .llseek
= seq_lseek
,
1580 .release
= seq_release
,
1583 static int __init
procswaps_init(void)
1585 proc_create("swaps", 0, NULL
, &proc_swaps_operations
);
1588 __initcall(procswaps_init
);
1589 #endif /* CONFIG_PROC_FS */
1591 #ifdef MAX_SWAPFILES_CHECK
1592 static int __init
max_swapfiles_check(void)
1594 MAX_SWAPFILES_CHECK();
1597 late_initcall(max_swapfiles_check
);
1601 * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
1603 * The swapon system call
1605 asmlinkage
long sys_swapon(const char __user
* specialfile
, int swap_flags
)
1607 struct swap_info_struct
* p
;
1609 struct block_device
*bdev
= NULL
;
1610 struct file
*swap_file
= NULL
;
1611 struct address_space
*mapping
;
1615 union swap_header
*swap_header
= NULL
;
1616 unsigned int nr_good_pages
= 0;
1619 unsigned long maxpages
= 1;
1620 unsigned long swapfilepages
;
1621 unsigned short *swap_map
= NULL
;
1622 struct page
*page
= NULL
;
1623 struct inode
*inode
= NULL
;
1626 if (!capable(CAP_SYS_ADMIN
))
1628 spin_lock(&swap_lock
);
1630 for (type
= 0 ; type
< nr_swapfiles
; type
++,p
++)
1631 if (!(p
->flags
& SWP_USED
))
1634 if (type
>= MAX_SWAPFILES
) {
1635 spin_unlock(&swap_lock
);
1638 if (type
>= nr_swapfiles
)
1639 nr_swapfiles
= type
+1;
1640 memset(p
, 0, sizeof(*p
));
1641 INIT_LIST_HEAD(&p
->extent_list
);
1642 p
->flags
= SWP_USED
;
1644 spin_unlock(&swap_lock
);
1645 name
= getname(specialfile
);
1646 error
= PTR_ERR(name
);
1651 swap_file
= filp_open(name
, O_RDWR
|O_LARGEFILE
, 0);
1652 error
= PTR_ERR(swap_file
);
1653 if (IS_ERR(swap_file
)) {
1658 p
->swap_file
= swap_file
;
1659 mapping
= swap_file
->f_mapping
;
1660 inode
= mapping
->host
;
1663 for (i
= 0; i
< nr_swapfiles
; i
++) {
1664 struct swap_info_struct
*q
= &swap_info
[i
];
1666 if (i
== type
|| !q
->swap_file
)
1668 if (mapping
== q
->swap_file
->f_mapping
)
1673 if (S_ISBLK(inode
->i_mode
)) {
1674 bdev
= I_BDEV(inode
);
1675 error
= bd_claim(bdev
, sys_swapon
);
1681 p
->old_block_size
= block_size(bdev
);
1682 error
= set_blocksize(bdev
, PAGE_SIZE
);
1686 } else if (S_ISREG(inode
->i_mode
)) {
1687 p
->bdev
= inode
->i_sb
->s_bdev
;
1688 mutex_lock(&inode
->i_mutex
);
1690 if (IS_SWAPFILE(inode
)) {
1698 swapfilepages
= i_size_read(inode
) >> PAGE_SHIFT
;
1701 * Read the swap header.
1703 if (!mapping
->a_ops
->readpage
) {
1707 page
= read_mapping_page(mapping
, 0, swap_file
);
1709 error
= PTR_ERR(page
);
1712 swap_header
= kmap(page
);
1714 if (memcmp("SWAPSPACE2", swap_header
->magic
.magic
, 10)) {
1715 printk(KERN_ERR
"Unable to find swap-space signature\n");
1720 /* swap partition endianess hack... */
1721 if (swab32(swap_header
->info
.version
) == 1) {
1722 swab32s(&swap_header
->info
.version
);
1723 swab32s(&swap_header
->info
.last_page
);
1724 swab32s(&swap_header
->info
.nr_badpages
);
1725 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++)
1726 swab32s(&swap_header
->info
.badpages
[i
]);
1728 /* Check the swap header's sub-version */
1729 if (swap_header
->info
.version
!= 1) {
1731 "Unable to handle swap header version %d\n",
1732 swap_header
->info
.version
);
1738 p
->cluster_next
= 1;
1741 * Find out how many pages are allowed for a single swap
1742 * device. There are two limiting factors: 1) the number of
1743 * bits for the swap offset in the swp_entry_t type and
1744 * 2) the number of bits in the a swap pte as defined by
1745 * the different architectures. In order to find the
1746 * largest possible bit mask a swap entry with swap type 0
1747 * and swap offset ~0UL is created, encoded to a swap pte,
1748 * decoded to a swp_entry_t again and finally the swap
1749 * offset is extracted. This will mask all the bits from
1750 * the initial ~0UL mask that can't be encoded in either
1751 * the swp_entry_t or the architecture definition of a
1754 maxpages
= swp_offset(pte_to_swp_entry(
1755 swp_entry_to_pte(swp_entry(0, ~0UL)))) - 1;
1756 if (maxpages
> swap_header
->info
.last_page
)
1757 maxpages
= swap_header
->info
.last_page
;
1758 p
->highest_bit
= maxpages
- 1;
1763 if (swapfilepages
&& maxpages
> swapfilepages
) {
1765 "Swap area shorter than signature indicates\n");
1768 if (swap_header
->info
.nr_badpages
&& S_ISREG(inode
->i_mode
))
1770 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
1773 /* OK, set up the swap map and apply the bad block list */
1774 swap_map
= vmalloc(maxpages
* sizeof(short));
1780 memset(swap_map
, 0, maxpages
* sizeof(short));
1781 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++) {
1782 int page_nr
= swap_header
->info
.badpages
[i
];
1783 if (page_nr
<= 0 || page_nr
>= swap_header
->info
.last_page
) {
1787 swap_map
[page_nr
] = SWAP_MAP_BAD
;
1789 nr_good_pages
= swap_header
->info
.last_page
-
1790 swap_header
->info
.nr_badpages
-
1791 1 /* header page */;
1793 if (nr_good_pages
) {
1794 swap_map
[0] = SWAP_MAP_BAD
;
1796 p
->pages
= nr_good_pages
;
1797 nr_extents
= setup_swap_extents(p
, &span
);
1798 if (nr_extents
< 0) {
1802 nr_good_pages
= p
->pages
;
1804 if (!nr_good_pages
) {
1805 printk(KERN_WARNING
"Empty swap-file\n");
1810 if (blk_queue_nonrot(bdev_get_queue(p
->bdev
))) {
1811 p
->flags
|= SWP_SOLIDSTATE
;
1812 srandom32((u32
)get_seconds());
1813 p
->cluster_next
= 1 + (random32() % p
->highest_bit
);
1815 if (discard_swap(p
) == 0)
1816 p
->flags
|= SWP_DISCARDABLE
;
1818 mutex_lock(&swapon_mutex
);
1819 spin_lock(&swap_lock
);
1820 if (swap_flags
& SWAP_FLAG_PREFER
)
1822 (swap_flags
& SWAP_FLAG_PRIO_MASK
) >> SWAP_FLAG_PRIO_SHIFT
;
1824 p
->prio
= --least_priority
;
1825 p
->swap_map
= swap_map
;
1826 p
->flags
|= SWP_WRITEOK
;
1827 nr_swap_pages
+= nr_good_pages
;
1828 total_swap_pages
+= nr_good_pages
;
1830 printk(KERN_INFO
"Adding %uk swap on %s. "
1831 "Priority:%d extents:%d across:%lluk %s%s\n",
1832 nr_good_pages
<<(PAGE_SHIFT
-10), name
, p
->prio
,
1833 nr_extents
, (unsigned long long)span
<<(PAGE_SHIFT
-10),
1834 (p
->flags
& SWP_SOLIDSTATE
) ? "SS" : "",
1835 (p
->flags
& SWP_DISCARDABLE
) ? "D" : "");
1837 /* insert swap space into swap_list: */
1839 for (i
= swap_list
.head
; i
>= 0; i
= swap_info
[i
].next
) {
1840 if (p
->prio
>= swap_info
[i
].prio
) {
1847 swap_list
.head
= swap_list
.next
= p
- swap_info
;
1849 swap_info
[prev
].next
= p
- swap_info
;
1851 spin_unlock(&swap_lock
);
1852 mutex_unlock(&swapon_mutex
);
1857 set_blocksize(bdev
, p
->old_block_size
);
1860 destroy_swap_extents(p
);
1862 spin_lock(&swap_lock
);
1863 p
->swap_file
= NULL
;
1865 spin_unlock(&swap_lock
);
1868 filp_close(swap_file
, NULL
);
1870 if (page
&& !IS_ERR(page
)) {
1872 page_cache_release(page
);
1878 inode
->i_flags
|= S_SWAPFILE
;
1879 mutex_unlock(&inode
->i_mutex
);
1884 void si_swapinfo(struct sysinfo
*val
)
1887 unsigned long nr_to_be_unused
= 0;
1889 spin_lock(&swap_lock
);
1890 for (i
= 0; i
< nr_swapfiles
; i
++) {
1891 if (!(swap_info
[i
].flags
& SWP_USED
) ||
1892 (swap_info
[i
].flags
& SWP_WRITEOK
))
1894 nr_to_be_unused
+= swap_info
[i
].inuse_pages
;
1896 val
->freeswap
= nr_swap_pages
+ nr_to_be_unused
;
1897 val
->totalswap
= total_swap_pages
+ nr_to_be_unused
;
1898 spin_unlock(&swap_lock
);
1902 * Verify that a swap entry is valid and increment its swap map count.
1904 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
1905 * "permanent", but will be reclaimed by the next swapoff.
1907 int swap_duplicate(swp_entry_t entry
)
1909 struct swap_info_struct
* p
;
1910 unsigned long offset
, type
;
1913 if (is_migration_entry(entry
))
1916 type
= swp_type(entry
);
1917 if (type
>= nr_swapfiles
)
1919 p
= type
+ swap_info
;
1920 offset
= swp_offset(entry
);
1922 spin_lock(&swap_lock
);
1923 if (offset
< p
->max
&& p
->swap_map
[offset
]) {
1924 if (p
->swap_map
[offset
] < SWAP_MAP_MAX
- 1) {
1925 p
->swap_map
[offset
]++;
1927 } else if (p
->swap_map
[offset
] <= SWAP_MAP_MAX
) {
1928 if (swap_overflow
++ < 5)
1929 printk(KERN_WARNING
"swap_dup: swap entry overflow\n");
1930 p
->swap_map
[offset
] = SWAP_MAP_MAX
;
1934 spin_unlock(&swap_lock
);
1939 printk(KERN_ERR
"swap_dup: %s%08lx\n", Bad_file
, entry
.val
);
1943 struct swap_info_struct
*
1944 get_swap_info_struct(unsigned type
)
1946 return &swap_info
[type
];
1950 * swap_lock prevents swap_map being freed. Don't grab an extra
1951 * reference on the swaphandle, it doesn't matter if it becomes unused.
1953 int valid_swaphandles(swp_entry_t entry
, unsigned long *offset
)
1955 struct swap_info_struct
*si
;
1956 int our_page_cluster
= page_cluster
;
1957 pgoff_t target
, toff
;
1961 if (!our_page_cluster
) /* no readahead */
1964 si
= &swap_info
[swp_type(entry
)];
1965 target
= swp_offset(entry
);
1966 base
= (target
>> our_page_cluster
) << our_page_cluster
;
1967 end
= base
+ (1 << our_page_cluster
);
1968 if (!base
) /* first page is swap header */
1971 spin_lock(&swap_lock
);
1972 if (end
> si
->max
) /* don't go beyond end of map */
1975 /* Count contiguous allocated slots above our target */
1976 for (toff
= target
; ++toff
< end
; nr_pages
++) {
1977 /* Don't read in free or bad pages */
1978 if (!si
->swap_map
[toff
])
1980 if (si
->swap_map
[toff
] == SWAP_MAP_BAD
)
1983 /* Count contiguous allocated slots below our target */
1984 for (toff
= target
; --toff
>= base
; nr_pages
++) {
1985 /* Don't read in free or bad pages */
1986 if (!si
->swap_map
[toff
])
1988 if (si
->swap_map
[toff
] == SWAP_MAP_BAD
)
1991 spin_unlock(&swap_lock
);
1994 * Indicate starting offset, and return number of pages to get:
1995 * if only 1, say 0, since there's then no readahead to be done.
1998 return nr_pages
? ++nr_pages
: 0;