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9#include <linux/module.h>
10#include <linux/mm.h>
11#include <linux/gfp.h>
12#include <linux/kernel_stat.h>
13#include <linux/swap.h>
14#include <linux/swapops.h>
15#include <linux/init.h>
16#include <linux/pagemap.h>
17#include <linux/buffer_head.h>
18#include <linux/backing-dev.h>
19#include <linux/pagevec.h>
20#include <linux/migrate.h>
21#include <linux/page_cgroup.h>
22
23#include <asm/pgtable.h>
24
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29
30static const struct address_space_operations swap_aops = {
31 .writepage = swap_writepage,
32 .sync_page = block_sync_page,
33 .set_page_dirty = __set_page_dirty_nobuffers,
34 .migratepage = migrate_page,
35};
36
37static struct backing_dev_info swap_backing_dev_info = {
38 .name = "swap",
39 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
40 .unplug_io_fn = swap_unplug_io_fn,
41};
42
43struct address_space swapper_space = {
44 .page_tree = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
45 .tree_lock = __SPIN_LOCK_UNLOCKED(swapper_space.tree_lock),
46 .a_ops = &swap_aops,
47 .i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear),
48 .backing_dev_info = &swap_backing_dev_info,
49};
50
51#define INC_CACHE_INFO(x) do { swap_cache_info.x++; } while (0)
52
53static struct {
54 unsigned long add_total;
55 unsigned long del_total;
56 unsigned long find_success;
57 unsigned long find_total;
58} swap_cache_info;
59
60void show_swap_cache_info(void)
61{
62 printk("%lu pages in swap cache\n", total_swapcache_pages);
63 printk("Swap cache stats: add %lu, delete %lu, find %lu/%lu\n",
64 swap_cache_info.add_total, swap_cache_info.del_total,
65 swap_cache_info.find_success, swap_cache_info.find_total);
66 printk("Free swap = %ldkB\n", nr_swap_pages << (PAGE_SHIFT - 10));
67 printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10));
68}
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73
74static int __add_to_swap_cache(struct page *page, swp_entry_t entry)
75{
76 int error;
77
78 VM_BUG_ON(!PageLocked(page));
79 VM_BUG_ON(PageSwapCache(page));
80 VM_BUG_ON(!PageSwapBacked(page));
81
82 page_cache_get(page);
83 SetPageSwapCache(page);
84 set_page_private(page, entry.val);
85
86 spin_lock_irq(&swapper_space.tree_lock);
87 error = radix_tree_insert(&swapper_space.page_tree, entry.val, page);
88 if (likely(!error)) {
89 total_swapcache_pages++;
90 __inc_zone_page_state(page, NR_FILE_PAGES);
91 INC_CACHE_INFO(add_total);
92 }
93 spin_unlock_irq(&swapper_space.tree_lock);
94
95 if (unlikely(error)) {
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101 VM_BUG_ON(error == -EEXIST);
102 set_page_private(page, 0UL);
103 ClearPageSwapCache(page);
104 page_cache_release(page);
105 }
106
107 return error;
108}
109
110
111int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
112{
113 int error;
114
115 error = radix_tree_preload(gfp_mask);
116 if (!error) {
117 error = __add_to_swap_cache(page, entry);
118 radix_tree_preload_end();
119 }
120 return error;
121}
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126
127void __delete_from_swap_cache(struct page *page)
128{
129 VM_BUG_ON(!PageLocked(page));
130 VM_BUG_ON(!PageSwapCache(page));
131 VM_BUG_ON(PageWriteback(page));
132
133 radix_tree_delete(&swapper_space.page_tree, page_private(page));
134 set_page_private(page, 0);
135 ClearPageSwapCache(page);
136 total_swapcache_pages--;
137 __dec_zone_page_state(page, NR_FILE_PAGES);
138 INC_CACHE_INFO(del_total);
139}
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147
148int add_to_swap(struct page *page)
149{
150 swp_entry_t entry;
151 int err;
152
153 VM_BUG_ON(!PageLocked(page));
154 VM_BUG_ON(!PageUptodate(page));
155
156 entry = get_swap_page();
157 if (!entry.val)
158 return 0;
159
160 if (unlikely(PageTransHuge(page)))
161 if (unlikely(split_huge_page(page))) {
162 swapcache_free(entry, NULL);
163 return 0;
164 }
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177 err = add_to_swap_cache(page, entry,
178 __GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN);
179
180 if (!err) {
181 SetPageDirty(page);
182 return 1;
183 } else {
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188 swapcache_free(entry, NULL);
189 return 0;
190 }
191}
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199void delete_from_swap_cache(struct page *page)
200{
201 swp_entry_t entry;
202
203 entry.val = page_private(page);
204
205 spin_lock_irq(&swapper_space.tree_lock);
206 __delete_from_swap_cache(page);
207 spin_unlock_irq(&swapper_space.tree_lock);
208
209 swapcache_free(entry, page);
210 page_cache_release(page);
211}
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220
221static inline void free_swap_cache(struct page *page)
222{
223 if (PageSwapCache(page) && !page_mapped(page) && trylock_page(page)) {
224 try_to_free_swap(page);
225 unlock_page(page);
226 }
227}
228
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233void free_page_and_swap_cache(struct page *page)
234{
235 free_swap_cache(page);
236 page_cache_release(page);
237}
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242
243void free_pages_and_swap_cache(struct page **pages, int nr)
244{
245 struct page **pagep = pages;
246
247 lru_add_drain();
248 while (nr) {
249 int todo = min(nr, PAGEVEC_SIZE);
250 int i;
251
252 for (i = 0; i < todo; i++)
253 free_swap_cache(pagep[i]);
254 release_pages(pagep, todo, 0);
255 pagep += todo;
256 nr -= todo;
257 }
258}
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266struct page * lookup_swap_cache(swp_entry_t entry)
267{
268 struct page *page;
269
270 page = find_get_page(&swapper_space, entry.val);
271
272 if (page)
273 INC_CACHE_INFO(find_success);
274
275 INC_CACHE_INFO(find_total);
276 return page;
277}
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285struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
286 struct vm_area_struct *vma, unsigned long addr)
287{
288 struct page *found_page, *new_page = NULL;
289 int err;
290
291 do {
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297 found_page = find_get_page(&swapper_space, entry.val);
298 if (found_page)
299 break;
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304 if (!new_page) {
305 new_page = alloc_page_vma(gfp_mask, vma, addr);
306 if (!new_page)
307 break;
308 }
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313 err = radix_tree_preload(gfp_mask & GFP_KERNEL);
314 if (err)
315 break;
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320 err = swapcache_prepare(entry);
321 if (err == -EEXIST) {
322 radix_tree_preload_end();
323 continue;
324 }
325 if (err) {
326 radix_tree_preload_end();
327 break;
328 }
329
330
331 __set_page_locked(new_page);
332 SetPageSwapBacked(new_page);
333 err = __add_to_swap_cache(new_page, entry);
334 if (likely(!err)) {
335 radix_tree_preload_end();
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339 lru_cache_add_anon(new_page);
340 swap_readpage(new_page);
341 return new_page;
342 }
343 radix_tree_preload_end();
344 ClearPageSwapBacked(new_page);
345 __clear_page_locked(new_page);
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350 swapcache_free(entry, NULL);
351 } while (err != -ENOMEM);
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353 if (new_page)
354 page_cache_release(new_page);
355 return found_page;
356}
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377struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
378 struct vm_area_struct *vma, unsigned long addr)
379{
380 int nr_pages;
381 struct page *page;
382 unsigned long offset;
383 unsigned long end_offset;
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392 nr_pages = valid_swaphandles(entry, &offset);
393 for (end_offset = offset + nr_pages; offset < end_offset; offset++) {
394
395 page = read_swap_cache_async(swp_entry(swp_type(entry), offset),
396 gfp_mask, vma, addr);
397 if (!page)
398 break;
399 page_cache_release(page);
400 }
401 lru_add_drain();
402 return read_swap_cache_async(entry, gfp_mask, vma, addr);
403}
404