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9#include <linux/mm.h>
10#include <linux/gfp.h>
11#include <linux/kernel_stat.h>
12#include <linux/swap.h>
13#include <linux/swapops.h>
14#include <linux/init.h>
15#include <linux/pagemap.h>
16#include <linux/backing-dev.h>
17#include <linux/blkdev.h>
18#include <linux/pagevec.h>
19#include <linux/migrate.h>
20#include <linux/page_cgroup.h>
21
22#include <asm/pgtable.h>
23
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26
27
28static const struct address_space_operations swap_aops = {
29 .writepage = swap_writepage,
30 .set_page_dirty = swap_set_page_dirty,
31 .migratepage = migrate_page,
32};
33
34static struct backing_dev_info swap_backing_dev_info = {
35 .name = "swap",
36 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
37};
38
39struct address_space swapper_spaces[MAX_SWAPFILES] = {
40 [0 ... MAX_SWAPFILES - 1] = {
41 .page_tree = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
42 .a_ops = &swap_aops,
43 .backing_dev_info = &swap_backing_dev_info,
44 }
45};
46
47#define INC_CACHE_INFO(x) do { swap_cache_info.x++; } while (0)
48
49static struct {
50 unsigned long add_total;
51 unsigned long del_total;
52 unsigned long find_success;
53 unsigned long find_total;
54} swap_cache_info;
55
56unsigned long total_swapcache_pages(void)
57{
58 int i;
59 unsigned long ret = 0;
60
61 for (i = 0; i < MAX_SWAPFILES; i++)
62 ret += swapper_spaces[i].nrpages;
63 return ret;
64}
65
66void show_swap_cache_info(void)
67{
68 printk("%lu pages in swap cache\n", total_swapcache_pages());
69 printk("Swap cache stats: add %lu, delete %lu, find %lu/%lu\n",
70 swap_cache_info.add_total, swap_cache_info.del_total,
71 swap_cache_info.find_success, swap_cache_info.find_total);
72 printk("Free swap = %ldkB\n",
73 get_nr_swap_pages() << (PAGE_SHIFT - 10));
74 printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10));
75}
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80
81int __add_to_swap_cache(struct page *page, swp_entry_t entry)
82{
83 int error;
84 struct address_space *address_space;
85
86 VM_BUG_ON(!PageLocked(page));
87 VM_BUG_ON(PageSwapCache(page));
88 VM_BUG_ON(!PageSwapBacked(page));
89
90 page_cache_get(page);
91 SetPageSwapCache(page);
92 set_page_private(page, entry.val);
93
94 address_space = swap_address_space(entry);
95 spin_lock_irq(&address_space->tree_lock);
96 error = radix_tree_insert(&address_space->page_tree,
97 entry.val, page);
98 if (likely(!error)) {
99 address_space->nrpages++;
100 __inc_zone_page_state(page, NR_FILE_PAGES);
101 INC_CACHE_INFO(add_total);
102 }
103 spin_unlock_irq(&address_space->tree_lock);
104
105 if (unlikely(error)) {
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111 VM_BUG_ON(error == -EEXIST);
112 set_page_private(page, 0UL);
113 ClearPageSwapCache(page);
114 page_cache_release(page);
115 }
116
117 return error;
118}
119
120
121int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
122{
123 int error;
124
125 error = radix_tree_preload(gfp_mask);
126 if (!error) {
127 error = __add_to_swap_cache(page, entry);
128 radix_tree_preload_end();
129 }
130 return error;
131}
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136
137void __delete_from_swap_cache(struct page *page)
138{
139 swp_entry_t entry;
140 struct address_space *address_space;
141
142 VM_BUG_ON(!PageLocked(page));
143 VM_BUG_ON(!PageSwapCache(page));
144 VM_BUG_ON(PageWriteback(page));
145
146 entry.val = page_private(page);
147 address_space = swap_address_space(entry);
148 radix_tree_delete(&address_space->page_tree, page_private(page));
149 set_page_private(page, 0);
150 ClearPageSwapCache(page);
151 address_space->nrpages--;
152 __dec_zone_page_state(page, NR_FILE_PAGES);
153 INC_CACHE_INFO(del_total);
154}
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162
163int add_to_swap(struct page *page, struct list_head *list)
164{
165 swp_entry_t entry;
166 int err;
167
168 VM_BUG_ON(!PageLocked(page));
169 VM_BUG_ON(!PageUptodate(page));
170
171 entry = get_swap_page();
172 if (!entry.val)
173 return 0;
174
175 if (unlikely(PageTransHuge(page)))
176 if (unlikely(split_huge_page_to_list(page, list))) {
177 swapcache_free(entry, NULL);
178 return 0;
179 }
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192 err = add_to_swap_cache(page, entry,
193 __GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN);
194
195 if (!err) {
196 SetPageDirty(page);
197 return 1;
198 } else {
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203 swapcache_free(entry, NULL);
204 return 0;
205 }
206}
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213
214void delete_from_swap_cache(struct page *page)
215{
216 swp_entry_t entry;
217 struct address_space *address_space;
218
219 entry.val = page_private(page);
220
221 address_space = swap_address_space(entry);
222 spin_lock_irq(&address_space->tree_lock);
223 __delete_from_swap_cache(page);
224 spin_unlock_irq(&address_space->tree_lock);
225
226 swapcache_free(entry, page);
227 page_cache_release(page);
228}
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237
238static inline void free_swap_cache(struct page *page)
239{
240 if (PageSwapCache(page) && !page_mapped(page) && trylock_page(page)) {
241 try_to_free_swap(page);
242 unlock_page(page);
243 }
244}
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250void free_page_and_swap_cache(struct page *page)
251{
252 free_swap_cache(page);
253 page_cache_release(page);
254}
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260void free_pages_and_swap_cache(struct page **pages, int nr)
261{
262 struct page **pagep = pages;
263
264 lru_add_drain();
265 while (nr) {
266 int todo = min(nr, PAGEVEC_SIZE);
267 int i;
268
269 for (i = 0; i < todo; i++)
270 free_swap_cache(pagep[i]);
271 release_pages(pagep, todo, 0);
272 pagep += todo;
273 nr -= todo;
274 }
275}
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283struct page * lookup_swap_cache(swp_entry_t entry)
284{
285 struct page *page;
286
287 page = find_get_page(swap_address_space(entry), entry.val);
288
289 if (page)
290 INC_CACHE_INFO(find_success);
291
292 INC_CACHE_INFO(find_total);
293 return page;
294}
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302struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
303 struct vm_area_struct *vma, unsigned long addr)
304{
305 struct page *found_page, *new_page = NULL;
306 int err;
307
308 do {
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314 found_page = find_get_page(swap_address_space(entry),
315 entry.val);
316 if (found_page)
317 break;
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321
322 if (!new_page) {
323 new_page = alloc_page_vma(gfp_mask, vma, addr);
324 if (!new_page)
325 break;
326 }
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331 err = radix_tree_preload(gfp_mask & GFP_KERNEL);
332 if (err)
333 break;
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338 err = swapcache_prepare(entry);
339 if (err == -EEXIST) {
340 radix_tree_preload_end();
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356 cond_resched();
357 continue;
358 }
359 if (err) {
360 radix_tree_preload_end();
361 break;
362 }
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365 __set_page_locked(new_page);
366 SetPageSwapBacked(new_page);
367 err = __add_to_swap_cache(new_page, entry);
368 if (likely(!err)) {
369 radix_tree_preload_end();
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373 lru_cache_add_anon(new_page);
374 swap_readpage(new_page);
375 return new_page;
376 }
377 radix_tree_preload_end();
378 ClearPageSwapBacked(new_page);
379 __clear_page_locked(new_page);
380
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384 swapcache_free(entry, NULL);
385 } while (err != -ENOMEM);
386
387 if (new_page)
388 page_cache_release(new_page);
389 return found_page;
390}
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411struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
412 struct vm_area_struct *vma, unsigned long addr)
413{
414 struct page *page;
415 unsigned long offset = swp_offset(entry);
416 unsigned long start_offset, end_offset;
417 unsigned long mask = (1UL << page_cluster) - 1;
418 struct blk_plug plug;
419
420
421 start_offset = offset & ~mask;
422 end_offset = offset | mask;
423 if (!start_offset)
424 start_offset++;
425
426 blk_start_plug(&plug);
427 for (offset = start_offset; offset <= end_offset ; offset++) {
428
429 page = read_swap_cache_async(swp_entry(swp_type(entry), offset),
430 gfp_mask, vma, addr);
431 if (!page)
432 continue;
433 page_cache_release(page);
434 }
435 blk_finish_plug(&plug);
436
437 lru_add_drain();
438 return read_swap_cache_async(entry, gfp_mask, vma, addr);
439}
440