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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /mm/swapfile.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'mm/swapfile.c')
-rw-r--r--mm/swapfile.c1672
1 files changed, 1672 insertions, 0 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
new file mode 100644
index 000000000000..a60e0075d55b
--- /dev/null
+++ b/mm/swapfile.c
@@ -0,0 +1,1672 @@
1/*
2 * linux/mm/swapfile.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 * Swap reorganised 29.12.95, Stephen Tweedie
6 */
7
8#include <linux/config.h>
9#include <linux/mm.h>
10#include <linux/hugetlb.h>
11#include <linux/mman.h>
12#include <linux/slab.h>
13#include <linux/kernel_stat.h>
14#include <linux/swap.h>
15#include <linux/vmalloc.h>
16#include <linux/pagemap.h>
17#include <linux/namei.h>
18#include <linux/shm.h>
19#include <linux/blkdev.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/syscalls.h>
29
30#include <asm/pgtable.h>
31#include <asm/tlbflush.h>
32#include <linux/swapops.h>
33
34DEFINE_SPINLOCK(swaplock);
35unsigned int nr_swapfiles;
36long total_swap_pages;
37static int swap_overflow;
38
39EXPORT_SYMBOL(total_swap_pages);
40
41static const char Bad_file[] = "Bad swap file entry ";
42static const char Unused_file[] = "Unused swap file entry ";
43static const char Bad_offset[] = "Bad swap offset entry ";
44static const char Unused_offset[] = "Unused swap offset entry ";
45
46struct swap_list_t swap_list = {-1, -1};
47
48struct swap_info_struct swap_info[MAX_SWAPFILES];
49
50static DECLARE_MUTEX(swapon_sem);
51
52/*
53 * We need this because the bdev->unplug_fn can sleep and we cannot
54 * hold swap_list_lock while calling the unplug_fn. And swap_list_lock
55 * cannot be turned into a semaphore.
56 */
57static DECLARE_RWSEM(swap_unplug_sem);
58
59#define SWAPFILE_CLUSTER 256
60
61void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page)
62{
63 swp_entry_t entry;
64
65 down_read(&swap_unplug_sem);
66 entry.val = page->private;
67 if (PageSwapCache(page)) {
68 struct block_device *bdev = swap_info[swp_type(entry)].bdev;
69 struct backing_dev_info *bdi;
70
71 /*
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 above. If
75 * 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.
78 */
79 WARN_ON(page_count(page) <= 1);
80
81 bdi = bdev->bd_inode->i_mapping->backing_dev_info;
82 bdi->unplug_io_fn(bdi, page);
83 }
84 up_read(&swap_unplug_sem);
85}
86
87static inline int scan_swap_map(struct swap_info_struct *si)
88{
89 unsigned long offset;
90 /*
91 * We try to cluster swap pages by allocating them
92 * sequentially in swap. Once we've allocated
93 * SWAPFILE_CLUSTER pages this way, however, we resort to
94 * first-free allocation, starting a new cluster. This
95 * prevents us from scattering swap pages all over the entire
96 * swap partition, so that we reduce overall disk seek times
97 * between swap pages. -- sct */
98 if (si->cluster_nr) {
99 while (si->cluster_next <= si->highest_bit) {
100 offset = si->cluster_next++;
101 if (si->swap_map[offset])
102 continue;
103 si->cluster_nr--;
104 goto got_page;
105 }
106 }
107 si->cluster_nr = SWAPFILE_CLUSTER;
108
109 /* try to find an empty (even not aligned) cluster. */
110 offset = si->lowest_bit;
111 check_next_cluster:
112 if (offset+SWAPFILE_CLUSTER-1 <= si->highest_bit)
113 {
114 unsigned long nr;
115 for (nr = offset; nr < offset+SWAPFILE_CLUSTER; nr++)
116 if (si->swap_map[nr])
117 {
118 offset = nr+1;
119 goto check_next_cluster;
120 }
121 /* We found a completly empty cluster, so start
122 * using it.
123 */
124 goto got_page;
125 }
126 /* No luck, so now go finegrined as usual. -Andrea */
127 for (offset = si->lowest_bit; offset <= si->highest_bit ; offset++) {
128 if (si->swap_map[offset])
129 continue;
130 si->lowest_bit = offset+1;
131 got_page:
132 if (offset == si->lowest_bit)
133 si->lowest_bit++;
134 if (offset == si->highest_bit)
135 si->highest_bit--;
136 if (si->lowest_bit > si->highest_bit) {
137 si->lowest_bit = si->max;
138 si->highest_bit = 0;
139 }
140 si->swap_map[offset] = 1;
141 si->inuse_pages++;
142 nr_swap_pages--;
143 si->cluster_next = offset+1;
144 return offset;
145 }
146 si->lowest_bit = si->max;
147 si->highest_bit = 0;
148 return 0;
149}
150
151swp_entry_t get_swap_page(void)
152{
153 struct swap_info_struct * p;
154 unsigned long offset;
155 swp_entry_t entry;
156 int type, wrapped = 0;
157
158 entry.val = 0; /* Out of memory */
159 swap_list_lock();
160 type = swap_list.next;
161 if (type < 0)
162 goto out;
163 if (nr_swap_pages <= 0)
164 goto out;
165
166 while (1) {
167 p = &swap_info[type];
168 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
169 swap_device_lock(p);
170 offset = scan_swap_map(p);
171 swap_device_unlock(p);
172 if (offset) {
173 entry = swp_entry(type,offset);
174 type = swap_info[type].next;
175 if (type < 0 ||
176 p->prio != swap_info[type].prio) {
177 swap_list.next = swap_list.head;
178 } else {
179 swap_list.next = type;
180 }
181 goto out;
182 }
183 }
184 type = p->next;
185 if (!wrapped) {
186 if (type < 0 || p->prio != swap_info[type].prio) {
187 type = swap_list.head;
188 wrapped = 1;
189 }
190 } else
191 if (type < 0)
192 goto out; /* out of swap space */
193 }
194out:
195 swap_list_unlock();
196 return entry;
197}
198
199static struct swap_info_struct * swap_info_get(swp_entry_t entry)
200{
201 struct swap_info_struct * p;
202 unsigned long offset, type;
203
204 if (!entry.val)
205 goto out;
206 type = swp_type(entry);
207 if (type >= nr_swapfiles)
208 goto bad_nofile;
209 p = & swap_info[type];
210 if (!(p->flags & SWP_USED))
211 goto bad_device;
212 offset = swp_offset(entry);
213 if (offset >= p->max)
214 goto bad_offset;
215 if (!p->swap_map[offset])
216 goto bad_free;
217 swap_list_lock();
218 if (p->prio > swap_info[swap_list.next].prio)
219 swap_list.next = type;
220 swap_device_lock(p);
221 return p;
222
223bad_free:
224 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val);
225 goto out;
226bad_offset:
227 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val);
228 goto out;
229bad_device:
230 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val);
231 goto out;
232bad_nofile:
233 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val);
234out:
235 return NULL;
236}
237
238static void swap_info_put(struct swap_info_struct * p)
239{
240 swap_device_unlock(p);
241 swap_list_unlock();
242}
243
244static int swap_entry_free(struct swap_info_struct *p, unsigned long offset)
245{
246 int count = p->swap_map[offset];
247
248 if (count < SWAP_MAP_MAX) {
249 count--;
250 p->swap_map[offset] = count;
251 if (!count) {
252 if (offset < p->lowest_bit)
253 p->lowest_bit = offset;
254 if (offset > p->highest_bit)
255 p->highest_bit = offset;
256 nr_swap_pages++;
257 p->inuse_pages--;
258 }
259 }
260 return count;
261}
262
263/*
264 * Caller has made sure that the swapdevice corresponding to entry
265 * is still around or has not been recycled.
266 */
267void swap_free(swp_entry_t entry)
268{
269 struct swap_info_struct * p;
270
271 p = swap_info_get(entry);
272 if (p) {
273 swap_entry_free(p, swp_offset(entry));
274 swap_info_put(p);
275 }
276}
277
278/*
279 * Check if we're the only user of a swap page,
280 * when the page is locked.
281 */
282static int exclusive_swap_page(struct page *page)
283{
284 int retval = 0;
285 struct swap_info_struct * p;
286 swp_entry_t entry;
287
288 entry.val = page->private;
289 p = swap_info_get(entry);
290 if (p) {
291 /* Is the only swap cache user the cache itself? */
292 if (p->swap_map[swp_offset(entry)] == 1) {
293 /* Recheck the page count with the swapcache lock held.. */
294 write_lock_irq(&swapper_space.tree_lock);
295 if (page_count(page) == 2)
296 retval = 1;
297 write_unlock_irq(&swapper_space.tree_lock);
298 }
299 swap_info_put(p);
300 }
301 return retval;
302}
303
304/*
305 * We can use this swap cache entry directly
306 * if there are no other references to it.
307 *
308 * Here "exclusive_swap_page()" does the real
309 * work, but we opportunistically check whether
310 * we need to get all the locks first..
311 */
312int can_share_swap_page(struct page *page)
313{
314 int retval = 0;
315
316 if (!PageLocked(page))
317 BUG();
318 switch (page_count(page)) {
319 case 3:
320 if (!PagePrivate(page))
321 break;
322 /* Fallthrough */
323 case 2:
324 if (!PageSwapCache(page))
325 break;
326 retval = exclusive_swap_page(page);
327 break;
328 case 1:
329 if (PageReserved(page))
330 break;
331 retval = 1;
332 }
333 return retval;
334}
335
336/*
337 * Work out if there are any other processes sharing this
338 * swap cache page. Free it if you can. Return success.
339 */
340int remove_exclusive_swap_page(struct page *page)
341{
342 int retval;
343 struct swap_info_struct * p;
344 swp_entry_t entry;
345
346 BUG_ON(PagePrivate(page));
347 BUG_ON(!PageLocked(page));
348
349 if (!PageSwapCache(page))
350 return 0;
351 if (PageWriteback(page))
352 return 0;
353 if (page_count(page) != 2) /* 2: us + cache */
354 return 0;
355
356 entry.val = page->private;
357 p = swap_info_get(entry);
358 if (!p)
359 return 0;
360
361 /* Is the only swap cache user the cache itself? */
362 retval = 0;
363 if (p->swap_map[swp_offset(entry)] == 1) {
364 /* Recheck the page count with the swapcache lock held.. */
365 write_lock_irq(&swapper_space.tree_lock);
366 if ((page_count(page) == 2) && !PageWriteback(page)) {
367 __delete_from_swap_cache(page);
368 SetPageDirty(page);
369 retval = 1;
370 }
371 write_unlock_irq(&swapper_space.tree_lock);
372 }
373 swap_info_put(p);
374
375 if (retval) {
376 swap_free(entry);
377 page_cache_release(page);
378 }
379
380 return retval;
381}
382
383/*
384 * Free the swap entry like above, but also try to
385 * free the page cache entry if it is the last user.
386 */
387void free_swap_and_cache(swp_entry_t entry)
388{
389 struct swap_info_struct * p;
390 struct page *page = NULL;
391
392 p = swap_info_get(entry);
393 if (p) {
394 if (swap_entry_free(p, swp_offset(entry)) == 1)
395 page = find_trylock_page(&swapper_space, entry.val);
396 swap_info_put(p);
397 }
398 if (page) {
399 int one_user;
400
401 BUG_ON(PagePrivate(page));
402 page_cache_get(page);
403 one_user = (page_count(page) == 2);
404 /* Only cache user (+us), or swap space full? Free it! */
405 if (!PageWriteback(page) && (one_user || vm_swap_full())) {
406 delete_from_swap_cache(page);
407 SetPageDirty(page);
408 }
409 unlock_page(page);
410 page_cache_release(page);
411 }
412}
413
414/*
415 * Always set the resulting pte to be nowrite (the same as COW pages
416 * after one process has exited). We don't know just how many PTEs will
417 * share this swap entry, so be cautious and let do_wp_page work out
418 * what to do if a write is requested later.
419 *
420 * vma->vm_mm->page_table_lock is held.
421 */
422static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
423 unsigned long addr, swp_entry_t entry, struct page *page)
424{
425 inc_mm_counter(vma->vm_mm, rss);
426 get_page(page);
427 set_pte_at(vma->vm_mm, addr, pte,
428 pte_mkold(mk_pte(page, vma->vm_page_prot)));
429 page_add_anon_rmap(page, vma, addr);
430 swap_free(entry);
431 /*
432 * Move the page to the active list so it is not
433 * immediately swapped out again after swapon.
434 */
435 activate_page(page);
436}
437
438static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
439 unsigned long addr, unsigned long end,
440 swp_entry_t entry, struct page *page)
441{
442 pte_t *pte;
443 pte_t swp_pte = swp_entry_to_pte(entry);
444
445 pte = pte_offset_map(pmd, addr);
446 do {
447 /*
448 * swapoff spends a _lot_ of time in this loop!
449 * Test inline before going to call unuse_pte.
450 */
451 if (unlikely(pte_same(*pte, swp_pte))) {
452 unuse_pte(vma, pte, addr, entry, page);
453 pte_unmap(pte);
454 return 1;
455 }
456 } while (pte++, addr += PAGE_SIZE, addr != end);
457 pte_unmap(pte - 1);
458 return 0;
459}
460
461static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
462 unsigned long addr, unsigned long end,
463 swp_entry_t entry, struct page *page)
464{
465 pmd_t *pmd;
466 unsigned long next;
467
468 pmd = pmd_offset(pud, addr);
469 do {
470 next = pmd_addr_end(addr, end);
471 if (pmd_none_or_clear_bad(pmd))
472 continue;
473 if (unuse_pte_range(vma, pmd, addr, next, entry, page))
474 return 1;
475 } while (pmd++, addr = next, addr != end);
476 return 0;
477}
478
479static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
480 unsigned long addr, unsigned long end,
481 swp_entry_t entry, struct page *page)
482{
483 pud_t *pud;
484 unsigned long next;
485
486 pud = pud_offset(pgd, addr);
487 do {
488 next = pud_addr_end(addr, end);
489 if (pud_none_or_clear_bad(pud))
490 continue;
491 if (unuse_pmd_range(vma, pud, addr, next, entry, page))
492 return 1;
493 } while (pud++, addr = next, addr != end);
494 return 0;
495}
496
497static int unuse_vma(struct vm_area_struct *vma,
498 swp_entry_t entry, struct page *page)
499{
500 pgd_t *pgd;
501 unsigned long addr, end, next;
502
503 if (page->mapping) {
504 addr = page_address_in_vma(page, vma);
505 if (addr == -EFAULT)
506 return 0;
507 else
508 end = addr + PAGE_SIZE;
509 } else {
510 addr = vma->vm_start;
511 end = vma->vm_end;
512 }
513
514 pgd = pgd_offset(vma->vm_mm, addr);
515 do {
516 next = pgd_addr_end(addr, end);
517 if (pgd_none_or_clear_bad(pgd))
518 continue;
519 if (unuse_pud_range(vma, pgd, addr, next, entry, page))
520 return 1;
521 } while (pgd++, addr = next, addr != end);
522 return 0;
523}
524
525static int unuse_mm(struct mm_struct *mm,
526 swp_entry_t entry, struct page *page)
527{
528 struct vm_area_struct *vma;
529
530 if (!down_read_trylock(&mm->mmap_sem)) {
531 /*
532 * Our reference to the page stops try_to_unmap_one from
533 * unmapping its ptes, so swapoff can make progress.
534 */
535 unlock_page(page);
536 down_read(&mm->mmap_sem);
537 lock_page(page);
538 }
539 spin_lock(&mm->page_table_lock);
540 for (vma = mm->mmap; vma; vma = vma->vm_next) {
541 if (vma->anon_vma && unuse_vma(vma, entry, page))
542 break;
543 }
544 spin_unlock(&mm->page_table_lock);
545 up_read(&mm->mmap_sem);
546 /*
547 * Currently unuse_mm cannot fail, but leave error handling
548 * at call sites for now, since we change it from time to time.
549 */
550 return 0;
551}
552
553/*
554 * Scan swap_map from current position to next entry still in use.
555 * Recycle to start on reaching the end, returning 0 when empty.
556 */
557static int find_next_to_unuse(struct swap_info_struct *si, int prev)
558{
559 int max = si->max;
560 int i = prev;
561 int count;
562
563 /*
564 * No need for swap_device_lock(si) here: we're just looking
565 * for whether an entry is in use, not modifying it; false
566 * hits are okay, and sys_swapoff() has already prevented new
567 * allocations from this area (while holding swap_list_lock()).
568 */
569 for (;;) {
570 if (++i >= max) {
571 if (!prev) {
572 i = 0;
573 break;
574 }
575 /*
576 * No entries in use at top of swap_map,
577 * loop back to start and recheck there.
578 */
579 max = prev + 1;
580 prev = 0;
581 i = 1;
582 }
583 count = si->swap_map[i];
584 if (count && count != SWAP_MAP_BAD)
585 break;
586 }
587 return i;
588}
589
590/*
591 * We completely avoid races by reading each swap page in advance,
592 * and then search for the process using it. All the necessary
593 * page table adjustments can then be made atomically.
594 */
595static int try_to_unuse(unsigned int type)
596{
597 struct swap_info_struct * si = &swap_info[type];
598 struct mm_struct *start_mm;
599 unsigned short *swap_map;
600 unsigned short swcount;
601 struct page *page;
602 swp_entry_t entry;
603 int i = 0;
604 int retval = 0;
605 int reset_overflow = 0;
606 int shmem;
607
608 /*
609 * When searching mms for an entry, a good strategy is to
610 * start at the first mm we freed the previous entry from
611 * (though actually we don't notice whether we or coincidence
612 * freed the entry). Initialize this start_mm with a hold.
613 *
614 * A simpler strategy would be to start at the last mm we
615 * freed the previous entry from; but that would take less
616 * advantage of mmlist ordering, which clusters forked mms
617 * together, child after parent. If we race with dup_mmap(), we
618 * prefer to resolve parent before child, lest we miss entries
619 * duplicated after we scanned child: using last mm would invert
620 * that. Though it's only a serious concern when an overflowed
621 * swap count is reset from SWAP_MAP_MAX, preventing a rescan.
622 */
623 start_mm = &init_mm;
624 atomic_inc(&init_mm.mm_users);
625
626 /*
627 * Keep on scanning until all entries have gone. Usually,
628 * one pass through swap_map is enough, but not necessarily:
629 * there are races when an instance of an entry might be missed.
630 */
631 while ((i = find_next_to_unuse(si, i)) != 0) {
632 if (signal_pending(current)) {
633 retval = -EINTR;
634 break;
635 }
636
637 /*
638 * Get a page for the entry, using the existing swap
639 * cache page if there is one. Otherwise, get a clean
640 * page and read the swap into it.
641 */
642 swap_map = &si->swap_map[i];
643 entry = swp_entry(type, i);
644 page = read_swap_cache_async(entry, NULL, 0);
645 if (!page) {
646 /*
647 * Either swap_duplicate() failed because entry
648 * has been freed independently, and will not be
649 * reused since sys_swapoff() already disabled
650 * allocation from here, or alloc_page() failed.
651 */
652 if (!*swap_map)
653 continue;
654 retval = -ENOMEM;
655 break;
656 }
657
658 /*
659 * Don't hold on to start_mm if it looks like exiting.
660 */
661 if (atomic_read(&start_mm->mm_users) == 1) {
662 mmput(start_mm);
663 start_mm = &init_mm;
664 atomic_inc(&init_mm.mm_users);
665 }
666
667 /*
668 * Wait for and lock page. When do_swap_page races with
669 * try_to_unuse, do_swap_page can handle the fault much
670 * faster than try_to_unuse can locate the entry. This
671 * apparently redundant "wait_on_page_locked" lets try_to_unuse
672 * defer to do_swap_page in such a case - in some tests,
673 * do_swap_page and try_to_unuse repeatedly compete.
674 */
675 wait_on_page_locked(page);
676 wait_on_page_writeback(page);
677 lock_page(page);
678 wait_on_page_writeback(page);
679
680 /*
681 * Remove all references to entry.
682 * Whenever we reach init_mm, there's no address space
683 * to search, but use it as a reminder to search shmem.
684 */
685 shmem = 0;
686 swcount = *swap_map;
687 if (swcount > 1) {
688 if (start_mm == &init_mm)
689 shmem = shmem_unuse(entry, page);
690 else
691 retval = unuse_mm(start_mm, entry, page);
692 }
693 if (*swap_map > 1) {
694 int set_start_mm = (*swap_map >= swcount);
695 struct list_head *p = &start_mm->mmlist;
696 struct mm_struct *new_start_mm = start_mm;
697 struct mm_struct *prev_mm = start_mm;
698 struct mm_struct *mm;
699
700 atomic_inc(&new_start_mm->mm_users);
701 atomic_inc(&prev_mm->mm_users);
702 spin_lock(&mmlist_lock);
703 while (*swap_map > 1 && !retval &&
704 (p = p->next) != &start_mm->mmlist) {
705 mm = list_entry(p, struct mm_struct, mmlist);
706 if (atomic_inc_return(&mm->mm_users) == 1) {
707 atomic_dec(&mm->mm_users);
708 continue;
709 }
710 spin_unlock(&mmlist_lock);
711 mmput(prev_mm);
712 prev_mm = mm;
713
714 cond_resched();
715
716 swcount = *swap_map;
717 if (swcount <= 1)
718 ;
719 else if (mm == &init_mm) {
720 set_start_mm = 1;
721 shmem = shmem_unuse(entry, page);
722 } else
723 retval = unuse_mm(mm, entry, page);
724 if (set_start_mm && *swap_map < swcount) {
725 mmput(new_start_mm);
726 atomic_inc(&mm->mm_users);
727 new_start_mm = mm;
728 set_start_mm = 0;
729 }
730 spin_lock(&mmlist_lock);
731 }
732 spin_unlock(&mmlist_lock);
733 mmput(prev_mm);
734 mmput(start_mm);
735 start_mm = new_start_mm;
736 }
737 if (retval) {
738 unlock_page(page);
739 page_cache_release(page);
740 break;
741 }
742
743 /*
744 * How could swap count reach 0x7fff when the maximum
745 * pid is 0x7fff, and there's no way to repeat a swap
746 * page within an mm (except in shmem, where it's the
747 * shared object which takes the reference count)?
748 * We believe SWAP_MAP_MAX cannot occur in Linux 2.4.
749 *
750 * If that's wrong, then we should worry more about
751 * exit_mmap() and do_munmap() cases described above:
752 * we might be resetting SWAP_MAP_MAX too early here.
753 * We know "Undead"s can happen, they're okay, so don't
754 * report them; but do report if we reset SWAP_MAP_MAX.
755 */
756 if (*swap_map == SWAP_MAP_MAX) {
757 swap_device_lock(si);
758 *swap_map = 1;
759 swap_device_unlock(si);
760 reset_overflow = 1;
761 }
762
763 /*
764 * If a reference remains (rare), we would like to leave
765 * the page in the swap cache; but try_to_unmap could
766 * then re-duplicate the entry once we drop page lock,
767 * so we might loop indefinitely; also, that page could
768 * not be swapped out to other storage meanwhile. So:
769 * delete from cache even if there's another reference,
770 * after ensuring that the data has been saved to disk -
771 * since if the reference remains (rarer), it will be
772 * read from disk into another page. Splitting into two
773 * pages would be incorrect if swap supported "shared
774 * private" pages, but they are handled by tmpfs files.
775 *
776 * Note shmem_unuse already deleted a swappage from
777 * the swap cache, unless the move to filepage failed:
778 * in which case it left swappage in cache, lowered its
779 * swap count to pass quickly through the loops above,
780 * and now we must reincrement count to try again later.
781 */
782 if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) {
783 struct writeback_control wbc = {
784 .sync_mode = WB_SYNC_NONE,
785 };
786
787 swap_writepage(page, &wbc);
788 lock_page(page);
789 wait_on_page_writeback(page);
790 }
791 if (PageSwapCache(page)) {
792 if (shmem)
793 swap_duplicate(entry);
794 else
795 delete_from_swap_cache(page);
796 }
797
798 /*
799 * So we could skip searching mms once swap count went
800 * to 1, we did not mark any present ptes as dirty: must
801 * mark page dirty so shrink_list will preserve it.
802 */
803 SetPageDirty(page);
804 unlock_page(page);
805 page_cache_release(page);
806
807 /*
808 * Make sure that we aren't completely killing
809 * interactive performance.
810 */
811 cond_resched();
812 }
813
814 mmput(start_mm);
815 if (reset_overflow) {
816 printk(KERN_WARNING "swapoff: cleared swap entry overflow\n");
817 swap_overflow = 0;
818 }
819 return retval;
820}
821
822/*
823 * After a successful try_to_unuse, if no swap is now in use, we know we
824 * can empty the mmlist. swap_list_lock must be held on entry and exit.
825 * Note that mmlist_lock nests inside swap_list_lock, and an mm must be
826 * added to the mmlist just after page_duplicate - before would be racy.
827 */
828static void drain_mmlist(void)
829{
830 struct list_head *p, *next;
831 unsigned int i;
832
833 for (i = 0; i < nr_swapfiles; i++)
834 if (swap_info[i].inuse_pages)
835 return;
836 spin_lock(&mmlist_lock);
837 list_for_each_safe(p, next, &init_mm.mmlist)
838 list_del_init(p);
839 spin_unlock(&mmlist_lock);
840}
841
842/*
843 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
844 * corresponds to page offset `offset'.
845 */
846sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset)
847{
848 struct swap_extent *se = sis->curr_swap_extent;
849 struct swap_extent *start_se = se;
850
851 for ( ; ; ) {
852 struct list_head *lh;
853
854 if (se->start_page <= offset &&
855 offset < (se->start_page + se->nr_pages)) {
856 return se->start_block + (offset - se->start_page);
857 }
858 lh = se->list.prev;
859 if (lh == &sis->extent_list)
860 lh = lh->prev;
861 se = list_entry(lh, struct swap_extent, list);
862 sis->curr_swap_extent = se;
863 BUG_ON(se == start_se); /* It *must* be present */
864 }
865}
866
867/*
868 * Free all of a swapdev's extent information
869 */
870static void destroy_swap_extents(struct swap_info_struct *sis)
871{
872 while (!list_empty(&sis->extent_list)) {
873 struct swap_extent *se;
874
875 se = list_entry(sis->extent_list.next,
876 struct swap_extent, list);
877 list_del(&se->list);
878 kfree(se);
879 }
880 sis->nr_extents = 0;
881}
882
883/*
884 * Add a block range (and the corresponding page range) into this swapdev's
885 * extent list. The extent list is kept sorted in block order.
886 *
887 * This function rather assumes that it is called in ascending sector_t order.
888 * It doesn't look for extent coalescing opportunities.
889 */
890static int
891add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
892 unsigned long nr_pages, sector_t start_block)
893{
894 struct swap_extent *se;
895 struct swap_extent *new_se;
896 struct list_head *lh;
897
898 lh = sis->extent_list.next; /* The highest-addressed block */
899 while (lh != &sis->extent_list) {
900 se = list_entry(lh, struct swap_extent, list);
901 if (se->start_block + se->nr_pages == start_block &&
902 se->start_page + se->nr_pages == start_page) {
903 /* Merge it */
904 se->nr_pages += nr_pages;
905 return 0;
906 }
907 lh = lh->next;
908 }
909
910 /*
911 * No merge. Insert a new extent, preserving ordering.
912 */
913 new_se = kmalloc(sizeof(*se), GFP_KERNEL);
914 if (new_se == NULL)
915 return -ENOMEM;
916 new_se->start_page = start_page;
917 new_se->nr_pages = nr_pages;
918 new_se->start_block = start_block;
919
920 lh = sis->extent_list.prev; /* The lowest block */
921 while (lh != &sis->extent_list) {
922 se = list_entry(lh, struct swap_extent, list);
923 if (se->start_block > start_block)
924 break;
925 lh = lh->prev;
926 }
927 list_add_tail(&new_se->list, lh);
928 sis->nr_extents++;
929 return 0;
930}
931
932/*
933 * A `swap extent' is a simple thing which maps a contiguous range of pages
934 * onto a contiguous range of disk blocks. An ordered list of swap extents
935 * is built at swapon time and is then used at swap_writepage/swap_readpage
936 * time for locating where on disk a page belongs.
937 *
938 * If the swapfile is an S_ISBLK block device, a single extent is installed.
939 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
940 * swap files identically.
941 *
942 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
943 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
944 * swapfiles are handled *identically* after swapon time.
945 *
946 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
947 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
948 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
949 * requirements, they are simply tossed out - we will never use those blocks
950 * for swapping.
951 *
952 * For S_ISREG swapfiles we hold i_sem across the life of the swapon. This
953 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
954 * which will scribble on the fs.
955 *
956 * The amount of disk space which a single swap extent represents varies.
957 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
958 * extents in the list. To avoid much list walking, we cache the previous
959 * search location in `curr_swap_extent', and start new searches from there.
960 * This is extremely effective. The average number of iterations in
961 * map_swap_page() has been measured at about 0.3 per page. - akpm.
962 */
963static int setup_swap_extents(struct swap_info_struct *sis)
964{
965 struct inode *inode;
966 unsigned blocks_per_page;
967 unsigned long page_no;
968 unsigned blkbits;
969 sector_t probe_block;
970 sector_t last_block;
971 int ret;
972
973 inode = sis->swap_file->f_mapping->host;
974 if (S_ISBLK(inode->i_mode)) {
975 ret = add_swap_extent(sis, 0, sis->max, 0);
976 goto done;
977 }
978
979 blkbits = inode->i_blkbits;
980 blocks_per_page = PAGE_SIZE >> blkbits;
981
982 /*
983 * Map all the blocks into the extent list. This code doesn't try
984 * to be very smart.
985 */
986 probe_block = 0;
987 page_no = 0;
988 last_block = i_size_read(inode) >> blkbits;
989 while ((probe_block + blocks_per_page) <= last_block &&
990 page_no < sis->max) {
991 unsigned block_in_page;
992 sector_t first_block;
993
994 first_block = bmap(inode, probe_block);
995 if (first_block == 0)
996 goto bad_bmap;
997
998 /*
999 * It must be PAGE_SIZE aligned on-disk
1000 */
1001 if (first_block & (blocks_per_page - 1)) {
1002 probe_block++;
1003 goto reprobe;
1004 }
1005
1006 for (block_in_page = 1; block_in_page < blocks_per_page;
1007 block_in_page++) {
1008 sector_t block;
1009
1010 block = bmap(inode, probe_block + block_in_page);
1011 if (block == 0)
1012 goto bad_bmap;
1013 if (block != first_block + block_in_page) {
1014 /* Discontiguity */
1015 probe_block++;
1016 goto reprobe;
1017 }
1018 }
1019
1020 /*
1021 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1022 */
1023 ret = add_swap_extent(sis, page_no, 1,
1024 first_block >> (PAGE_SHIFT - blkbits));
1025 if (ret)
1026 goto out;
1027 page_no++;
1028 probe_block += blocks_per_page;
1029reprobe:
1030 continue;
1031 }
1032 ret = 0;
1033 if (page_no == 0)
1034 ret = -EINVAL;
1035 sis->max = page_no;
1036 sis->highest_bit = page_no - 1;
1037done:
1038 sis->curr_swap_extent = list_entry(sis->extent_list.prev,
1039 struct swap_extent, list);
1040 goto out;
1041bad_bmap:
1042 printk(KERN_ERR "swapon: swapfile has holes\n");
1043 ret = -EINVAL;
1044out:
1045 return ret;
1046}
1047
1048#if 0 /* We don't need this yet */
1049#include <linux/backing-dev.h>
1050int page_queue_congested(struct page *page)
1051{
1052 struct backing_dev_info *bdi;
1053
1054 BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */
1055
1056 if (PageSwapCache(page)) {
1057 swp_entry_t entry = { .val = page->private };
1058 struct swap_info_struct *sis;
1059
1060 sis = get_swap_info_struct(swp_type(entry));
1061 bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info;
1062 } else
1063 bdi = page->mapping->backing_dev_info;
1064 return bdi_write_congested(bdi);
1065}
1066#endif
1067
1068asmlinkage long sys_swapoff(const char __user * specialfile)
1069{
1070 struct swap_info_struct * p = NULL;
1071 unsigned short *swap_map;
1072 struct file *swap_file, *victim;
1073 struct address_space *mapping;
1074 struct inode *inode;
1075 char * pathname;
1076 int i, type, prev;
1077 int err;
1078
1079 if (!capable(CAP_SYS_ADMIN))
1080 return -EPERM;
1081
1082 pathname = getname(specialfile);
1083 err = PTR_ERR(pathname);
1084 if (IS_ERR(pathname))
1085 goto out;
1086
1087 victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0);
1088 putname(pathname);
1089 err = PTR_ERR(victim);
1090 if (IS_ERR(victim))
1091 goto out;
1092
1093 mapping = victim->f_mapping;
1094 prev = -1;
1095 swap_list_lock();
1096 for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
1097 p = swap_info + type;
1098 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
1099 if (p->swap_file->f_mapping == mapping)
1100 break;
1101 }
1102 prev = type;
1103 }
1104 if (type < 0) {
1105 err = -EINVAL;
1106 swap_list_unlock();
1107 goto out_dput;
1108 }
1109 if (!security_vm_enough_memory(p->pages))
1110 vm_unacct_memory(p->pages);
1111 else {
1112 err = -ENOMEM;
1113 swap_list_unlock();
1114 goto out_dput;
1115 }
1116 if (prev < 0) {
1117 swap_list.head = p->next;
1118 } else {
1119 swap_info[prev].next = p->next;
1120 }
1121 if (type == swap_list.next) {
1122 /* just pick something that's safe... */
1123 swap_list.next = swap_list.head;
1124 }
1125 nr_swap_pages -= p->pages;
1126 total_swap_pages -= p->pages;
1127 p->flags &= ~SWP_WRITEOK;
1128 swap_list_unlock();
1129 current->flags |= PF_SWAPOFF;
1130 err = try_to_unuse(type);
1131 current->flags &= ~PF_SWAPOFF;
1132
1133 /* wait for any unplug function to finish */
1134 down_write(&swap_unplug_sem);
1135 up_write(&swap_unplug_sem);
1136
1137 if (err) {
1138 /* re-insert swap space back into swap_list */
1139 swap_list_lock();
1140 for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next)
1141 if (p->prio >= swap_info[i].prio)
1142 break;
1143 p->next = i;
1144 if (prev < 0)
1145 swap_list.head = swap_list.next = p - swap_info;
1146 else
1147 swap_info[prev].next = p - swap_info;
1148 nr_swap_pages += p->pages;
1149 total_swap_pages += p->pages;
1150 p->flags |= SWP_WRITEOK;
1151 swap_list_unlock();
1152 goto out_dput;
1153 }
1154 down(&swapon_sem);
1155 swap_list_lock();
1156 drain_mmlist();
1157 swap_device_lock(p);
1158 swap_file = p->swap_file;
1159 p->swap_file = NULL;
1160 p->max = 0;
1161 swap_map = p->swap_map;
1162 p->swap_map = NULL;
1163 p->flags = 0;
1164 destroy_swap_extents(p);
1165 swap_device_unlock(p);
1166 swap_list_unlock();
1167 up(&swapon_sem);
1168 vfree(swap_map);
1169 inode = mapping->host;
1170 if (S_ISBLK(inode->i_mode)) {
1171 struct block_device *bdev = I_BDEV(inode);
1172 set_blocksize(bdev, p->old_block_size);
1173 bd_release(bdev);
1174 } else {
1175 down(&inode->i_sem);
1176 inode->i_flags &= ~S_SWAPFILE;
1177 up(&inode->i_sem);
1178 }
1179 filp_close(swap_file, NULL);
1180 err = 0;
1181
1182out_dput:
1183 filp_close(victim, NULL);
1184out:
1185 return err;
1186}
1187
1188#ifdef CONFIG_PROC_FS
1189/* iterator */
1190static void *swap_start(struct seq_file *swap, loff_t *pos)
1191{
1192 struct swap_info_struct *ptr = swap_info;
1193 int i;
1194 loff_t l = *pos;
1195
1196 down(&swapon_sem);
1197
1198 for (i = 0; i < nr_swapfiles; i++, ptr++) {
1199 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1200 continue;
1201 if (!l--)
1202 return ptr;
1203 }
1204
1205 return NULL;
1206}
1207
1208static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
1209{
1210 struct swap_info_struct *ptr = v;
1211 struct swap_info_struct *endptr = swap_info + nr_swapfiles;
1212
1213 for (++ptr; ptr < endptr; ptr++) {
1214 if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
1215 continue;
1216 ++*pos;
1217 return ptr;
1218 }
1219
1220 return NULL;
1221}
1222
1223static void swap_stop(struct seq_file *swap, void *v)
1224{
1225 up(&swapon_sem);
1226}
1227
1228static int swap_show(struct seq_file *swap, void *v)
1229{
1230 struct swap_info_struct *ptr = v;
1231 struct file *file;
1232 int len;
1233
1234 if (v == swap_info)
1235 seq_puts(swap, "Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1236
1237 file = ptr->swap_file;
1238 len = seq_path(swap, file->f_vfsmnt, file->f_dentry, " \t\n\\");
1239 seq_printf(swap, "%*s%s\t%d\t%ld\t%d\n",
1240 len < 40 ? 40 - len : 1, " ",
1241 S_ISBLK(file->f_dentry->d_inode->i_mode) ?
1242 "partition" : "file\t",
1243 ptr->pages << (PAGE_SHIFT - 10),
1244 ptr->inuse_pages << (PAGE_SHIFT - 10),
1245 ptr->prio);
1246 return 0;
1247}
1248
1249static struct seq_operations swaps_op = {
1250 .start = swap_start,
1251 .next = swap_next,
1252 .stop = swap_stop,
1253 .show = swap_show
1254};
1255
1256static int swaps_open(struct inode *inode, struct file *file)
1257{
1258 return seq_open(file, &swaps_op);
1259}
1260
1261static struct file_operations proc_swaps_operations = {
1262 .open = swaps_open,
1263 .read = seq_read,
1264 .llseek = seq_lseek,
1265 .release = seq_release,
1266};
1267
1268static int __init procswaps_init(void)
1269{
1270 struct proc_dir_entry *entry;
1271
1272 entry = create_proc_entry("swaps", 0, NULL);
1273 if (entry)
1274 entry->proc_fops = &proc_swaps_operations;
1275 return 0;
1276}
1277__initcall(procswaps_init);
1278#endif /* CONFIG_PROC_FS */
1279
1280/*
1281 * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
1282 *
1283 * The swapon system call
1284 */
1285asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
1286{
1287 struct swap_info_struct * p;
1288 char *name = NULL;
1289 struct block_device *bdev = NULL;
1290 struct file *swap_file = NULL;
1291 struct address_space *mapping;
1292 unsigned int type;
1293 int i, prev;
1294 int error;
1295 static int least_priority;
1296 union swap_header *swap_header = NULL;
1297 int swap_header_version;
1298 int nr_good_pages = 0;
1299 unsigned long maxpages = 1;
1300 int swapfilesize;
1301 unsigned short *swap_map;
1302 struct page *page = NULL;
1303 struct inode *inode = NULL;
1304 int did_down = 0;
1305
1306 if (!capable(CAP_SYS_ADMIN))
1307 return -EPERM;
1308 swap_list_lock();
1309 p = swap_info;
1310 for (type = 0 ; type < nr_swapfiles ; type++,p++)
1311 if (!(p->flags & SWP_USED))
1312 break;
1313 error = -EPERM;
1314 /*
1315 * Test if adding another swap device is possible. There are
1316 * two limiting factors: 1) the number of bits for the swap
1317 * type swp_entry_t definition and 2) the number of bits for
1318 * the swap type in the swap ptes as defined by the different
1319 * architectures. To honor both limitations a swap entry
1320 * with swap offset 0 and swap type ~0UL is created, encoded
1321 * to a swap pte, decoded to a swp_entry_t again and finally
1322 * the swap type part is extracted. This will mask all bits
1323 * from the initial ~0UL that can't be encoded in either the
1324 * swp_entry_t or the architecture definition of a swap pte.
1325 */
1326 if (type > swp_type(pte_to_swp_entry(swp_entry_to_pte(swp_entry(~0UL,0))))) {
1327 swap_list_unlock();
1328 goto out;
1329 }
1330 if (type >= nr_swapfiles)
1331 nr_swapfiles = type+1;
1332 INIT_LIST_HEAD(&p->extent_list);
1333 p->flags = SWP_USED;
1334 p->nr_extents = 0;
1335 p->swap_file = NULL;
1336 p->old_block_size = 0;
1337 p->swap_map = NULL;
1338 p->lowest_bit = 0;
1339 p->highest_bit = 0;
1340 p->cluster_nr = 0;
1341 p->inuse_pages = 0;
1342 spin_lock_init(&p->sdev_lock);
1343 p->next = -1;
1344 if (swap_flags & SWAP_FLAG_PREFER) {
1345 p->prio =
1346 (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT;
1347 } else {
1348 p->prio = --least_priority;
1349 }
1350 swap_list_unlock();
1351 name = getname(specialfile);
1352 error = PTR_ERR(name);
1353 if (IS_ERR(name)) {
1354 name = NULL;
1355 goto bad_swap_2;
1356 }
1357 swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0);
1358 error = PTR_ERR(swap_file);
1359 if (IS_ERR(swap_file)) {
1360 swap_file = NULL;
1361 goto bad_swap_2;
1362 }
1363
1364 p->swap_file = swap_file;
1365 mapping = swap_file->f_mapping;
1366 inode = mapping->host;
1367
1368 error = -EBUSY;
1369 for (i = 0; i < nr_swapfiles; i++) {
1370 struct swap_info_struct *q = &swap_info[i];
1371
1372 if (i == type || !q->swap_file)
1373 continue;
1374 if (mapping == q->swap_file->f_mapping)
1375 goto bad_swap;
1376 }
1377
1378 error = -EINVAL;
1379 if (S_ISBLK(inode->i_mode)) {
1380 bdev = I_BDEV(inode);
1381 error = bd_claim(bdev, sys_swapon);
1382 if (error < 0) {
1383 bdev = NULL;
1384 goto bad_swap;
1385 }
1386 p->old_block_size = block_size(bdev);
1387 error = set_blocksize(bdev, PAGE_SIZE);
1388 if (error < 0)
1389 goto bad_swap;
1390 p->bdev = bdev;
1391 } else if (S_ISREG(inode->i_mode)) {
1392 p->bdev = inode->i_sb->s_bdev;
1393 down(&inode->i_sem);
1394 did_down = 1;
1395 if (IS_SWAPFILE(inode)) {
1396 error = -EBUSY;
1397 goto bad_swap;
1398 }
1399 } else {
1400 goto bad_swap;
1401 }
1402
1403 swapfilesize = i_size_read(inode) >> PAGE_SHIFT;
1404
1405 /*
1406 * Read the swap header.
1407 */
1408 if (!mapping->a_ops->readpage) {
1409 error = -EINVAL;
1410 goto bad_swap;
1411 }
1412 page = read_cache_page(mapping, 0,
1413 (filler_t *)mapping->a_ops->readpage, swap_file);
1414 if (IS_ERR(page)) {
1415 error = PTR_ERR(page);
1416 goto bad_swap;
1417 }
1418 wait_on_page_locked(page);
1419 if (!PageUptodate(page))
1420 goto bad_swap;
1421 kmap(page);
1422 swap_header = page_address(page);
1423
1424 if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
1425 swap_header_version = 1;
1426 else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
1427 swap_header_version = 2;
1428 else {
1429 printk("Unable to find swap-space signature\n");
1430 error = -EINVAL;
1431 goto bad_swap;
1432 }
1433
1434 switch (swap_header_version) {
1435 case 1:
1436 printk(KERN_ERR "version 0 swap is no longer supported. "
1437 "Use mkswap -v1 %s\n", name);
1438 error = -EINVAL;
1439 goto bad_swap;
1440 case 2:
1441 /* Check the swap header's sub-version and the size of
1442 the swap file and bad block lists */
1443 if (swap_header->info.version != 1) {
1444 printk(KERN_WARNING
1445 "Unable to handle swap header version %d\n",
1446 swap_header->info.version);
1447 error = -EINVAL;
1448 goto bad_swap;
1449 }
1450
1451 p->lowest_bit = 1;
1452 /*
1453 * Find out how many pages are allowed for a single swap
1454 * device. There are two limiting factors: 1) the number of
1455 * bits for the swap offset in the swp_entry_t type and
1456 * 2) the number of bits in the a swap pte as defined by
1457 * the different architectures. In order to find the
1458 * largest possible bit mask a swap entry with swap type 0
1459 * and swap offset ~0UL is created, encoded to a swap pte,
1460 * decoded to a swp_entry_t again and finally the swap
1461 * offset is extracted. This will mask all the bits from
1462 * the initial ~0UL mask that can't be encoded in either
1463 * the swp_entry_t or the architecture definition of a
1464 * swap pte.
1465 */
1466 maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1;
1467 if (maxpages > swap_header->info.last_page)
1468 maxpages = swap_header->info.last_page;
1469 p->highest_bit = maxpages - 1;
1470
1471 error = -EINVAL;
1472 if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
1473 goto bad_swap;
1474
1475 /* OK, set up the swap map and apply the bad block list */
1476 if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) {
1477 error = -ENOMEM;
1478 goto bad_swap;
1479 }
1480
1481 error = 0;
1482 memset(p->swap_map, 0, maxpages * sizeof(short));
1483 for (i=0; i<swap_header->info.nr_badpages; i++) {
1484 int page = swap_header->info.badpages[i];
1485 if (page <= 0 || page >= swap_header->info.last_page)
1486 error = -EINVAL;
1487 else
1488 p->swap_map[page] = SWAP_MAP_BAD;
1489 }
1490 nr_good_pages = swap_header->info.last_page -
1491 swap_header->info.nr_badpages -
1492 1 /* header page */;
1493 if (error)
1494 goto bad_swap;
1495 }
1496
1497 if (swapfilesize && maxpages > swapfilesize) {
1498 printk(KERN_WARNING
1499 "Swap area shorter than signature indicates\n");
1500 error = -EINVAL;
1501 goto bad_swap;
1502 }
1503 if (!nr_good_pages) {
1504 printk(KERN_WARNING "Empty swap-file\n");
1505 error = -EINVAL;
1506 goto bad_swap;
1507 }
1508 p->swap_map[0] = SWAP_MAP_BAD;
1509 p->max = maxpages;
1510 p->pages = nr_good_pages;
1511
1512 error = setup_swap_extents(p);
1513 if (error)
1514 goto bad_swap;
1515
1516 down(&swapon_sem);
1517 swap_list_lock();
1518 swap_device_lock(p);
1519 p->flags = SWP_ACTIVE;
1520 nr_swap_pages += nr_good_pages;
1521 total_swap_pages += nr_good_pages;
1522 printk(KERN_INFO "Adding %dk swap on %s. Priority:%d extents:%d\n",
1523 nr_good_pages<<(PAGE_SHIFT-10), name,
1524 p->prio, p->nr_extents);
1525
1526 /* insert swap space into swap_list: */
1527 prev = -1;
1528 for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
1529 if (p->prio >= swap_info[i].prio) {
1530 break;
1531 }
1532 prev = i;
1533 }
1534 p->next = i;
1535 if (prev < 0) {
1536 swap_list.head = swap_list.next = p - swap_info;
1537 } else {
1538 swap_info[prev].next = p - swap_info;
1539 }
1540 swap_device_unlock(p);
1541 swap_list_unlock();
1542 up(&swapon_sem);
1543 error = 0;
1544 goto out;
1545bad_swap:
1546 if (bdev) {
1547 set_blocksize(bdev, p->old_block_size);
1548 bd_release(bdev);
1549 }
1550bad_swap_2:
1551 swap_list_lock();
1552 swap_map = p->swap_map;
1553 p->swap_file = NULL;
1554 p->swap_map = NULL;
1555 p->flags = 0;
1556 if (!(swap_flags & SWAP_FLAG_PREFER))
1557 ++least_priority;
1558 swap_list_unlock();
1559 destroy_swap_extents(p);
1560 vfree(swap_map);
1561 if (swap_file)
1562 filp_close(swap_file, NULL);
1563out:
1564 if (page && !IS_ERR(page)) {
1565 kunmap(page);
1566 page_cache_release(page);
1567 }
1568 if (name)
1569 putname(name);
1570 if (did_down) {
1571 if (!error)
1572 inode->i_flags |= S_SWAPFILE;
1573 up(&inode->i_sem);
1574 }
1575 return error;
1576}
1577
1578void si_swapinfo(struct sysinfo *val)
1579{
1580 unsigned int i;
1581 unsigned long nr_to_be_unused = 0;
1582
1583 swap_list_lock();
1584 for (i = 0; i < nr_swapfiles; i++) {
1585 if (!(swap_info[i].flags & SWP_USED) ||
1586 (swap_info[i].flags & SWP_WRITEOK))
1587 continue;
1588 nr_to_be_unused += swap_info[i].inuse_pages;
1589 }
1590 val->freeswap = nr_swap_pages + nr_to_be_unused;
1591 val->totalswap = total_swap_pages + nr_to_be_unused;
1592 swap_list_unlock();
1593}
1594
1595/*
1596 * Verify that a swap entry is valid and increment its swap map count.
1597 *
1598 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
1599 * "permanent", but will be reclaimed by the next swapoff.
1600 */
1601int swap_duplicate(swp_entry_t entry)
1602{
1603 struct swap_info_struct * p;
1604 unsigned long offset, type;
1605 int result = 0;
1606
1607 type = swp_type(entry);
1608 if (type >= nr_swapfiles)
1609 goto bad_file;
1610 p = type + swap_info;
1611 offset = swp_offset(entry);
1612
1613 swap_device_lock(p);
1614 if (offset < p->max && p->swap_map[offset]) {
1615 if (p->swap_map[offset] < SWAP_MAP_MAX - 1) {
1616 p->swap_map[offset]++;
1617 result = 1;
1618 } else if (p->swap_map[offset] <= SWAP_MAP_MAX) {
1619 if (swap_overflow++ < 5)
1620 printk(KERN_WARNING "swap_dup: swap entry overflow\n");
1621 p->swap_map[offset] = SWAP_MAP_MAX;
1622 result = 1;
1623 }
1624 }
1625 swap_device_unlock(p);
1626out:
1627 return result;
1628
1629bad_file:
1630 printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
1631 goto out;
1632}
1633
1634struct swap_info_struct *
1635get_swap_info_struct(unsigned type)
1636{
1637 return &swap_info[type];
1638}
1639
1640/*
1641 * swap_device_lock prevents swap_map being freed. Don't grab an extra
1642 * reference on the swaphandle, it doesn't matter if it becomes unused.
1643 */
1644int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
1645{
1646 int ret = 0, i = 1 << page_cluster;
1647 unsigned long toff;
1648 struct swap_info_struct *swapdev = swp_type(entry) + swap_info;
1649
1650 if (!page_cluster) /* no readahead */
1651 return 0;
1652 toff = (swp_offset(entry) >> page_cluster) << page_cluster;
1653 if (!toff) /* first page is swap header */
1654 toff++, i--;
1655 *offset = toff;
1656
1657 swap_device_lock(swapdev);
1658 do {
1659 /* Don't read-ahead past the end of the swap area */
1660 if (toff >= swapdev->max)
1661 break;
1662 /* Don't read in free or bad pages */
1663 if (!swapdev->swap_map[toff])
1664 break;
1665 if (swapdev->swap_map[toff] == SWAP_MAP_BAD)
1666 break;
1667 toff++;
1668 ret++;
1669 } while (--i);
1670 swap_device_unlock(swapdev);
1671 return ret;
1672}
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-07 09:45:26 -0500