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9#include <linux/module.h>
10#include <linux/mm.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/buffer_head.h>
17#include <linux/backing-dev.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
28
29static const struct address_space_operations swap_aops = {
30 .writepage = swap_writepage,
31 .sync_page = block_sync_page,
32 .set_page_dirty = __set_page_dirty_nobuffers,
33 .migratepage = migrate_page,
34};
35
36static struct backing_dev_info swap_backing_dev_info = {
37 .name = "swap",
38 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
39 .unplug_io_fn = swap_unplug_io_fn,
40};
41
42struct address_space swapper_space = {
43 .page_tree = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
44 .tree_lock = __SPIN_LOCK_UNLOCKED(swapper_space.tree_lock),
45 .a_ops = &swap_aops,
46 .i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear),
47 .backing_dev_info = &swap_backing_dev_info,
48};
49
50#define INC_CACHE_INFO(x) do { swap_cache_info.x++; } while (0)
51
52static struct {
53 unsigned long add_total;
54 unsigned long del_total;
55 unsigned long find_success;
56 unsigned long find_total;
57} swap_cache_info;
58
59void show_swap_cache_info(void)
60{
61 printk("%lu pages in swap cache\n", total_swapcache_pages);
62 printk("Swap cache stats: add %lu, delete %lu, find %lu/%lu\n",
63 swap_cache_info.add_total, swap_cache_info.del_total,
64 swap_cache_info.find_success, swap_cache_info.find_total);
65 printk("Free swap = %ldkB\n", nr_swap_pages << (PAGE_SHIFT - 10));
66 printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10));
67}
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72
73static int __add_to_swap_cache(struct page *page, swp_entry_t entry)
74{
75 int error;
76
77 VM_BUG_ON(!PageLocked(page));
78 VM_BUG_ON(PageSwapCache(page));
79 VM_BUG_ON(!PageSwapBacked(page));
80
81 page_cache_get(page);
82 SetPageSwapCache(page);
83 set_page_private(page, entry.val);
84
85 spin_lock_irq(&swapper_space.tree_lock);
86 error = radix_tree_insert(&swapper_space.page_tree, entry.val, page);
87 if (likely(!error)) {
88 total_swapcache_pages++;
89 __inc_zone_page_state(page, NR_FILE_PAGES);
90 INC_CACHE_INFO(add_total);
91 }
92 spin_unlock_irq(&swapper_space.tree_lock);
93
94 if (unlikely(error)) {
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100 VM_BUG_ON(error == -EEXIST);
101 set_page_private(page, 0UL);
102 ClearPageSwapCache(page);
103 page_cache_release(page);
104 }
105
106 return error;
107}
108
109
110int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
111{
112 int error;
113
114 error = radix_tree_preload(gfp_mask);
115 if (!error) {
116 error = __add_to_swap_cache(page, entry);
117 radix_tree_preload_end();
118 }
119 return error;
120}
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125
126void __delete_from_swap_cache(struct page *page)
127{
128 VM_BUG_ON(!PageLocked(page));
129 VM_BUG_ON(!PageSwapCache(page));
130 VM_BUG_ON(PageWriteback(page));
131
132 radix_tree_delete(&swapper_space.page_tree, page_private(page));
133 set_page_private(page, 0);
134 ClearPageSwapCache(page);
135 total_swapcache_pages--;
136 __dec_zone_page_state(page, NR_FILE_PAGES);
137 INC_CACHE_INFO(del_total);
138}
139
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146
147int add_to_swap(struct page *page)
148{
149 swp_entry_t entry;
150 int err;
151
152 VM_BUG_ON(!PageLocked(page));
153 VM_BUG_ON(!PageUptodate(page));
154
155 entry = get_swap_page();
156 if (!entry.val)
157 return 0;
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169
170 err = add_to_swap_cache(page, entry,
171 __GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN);
172
173 if (!err) {
174 SetPageDirty(page);
175 return 1;
176 } else {
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181 swapcache_free(entry, NULL);
182 return 0;
183 }
184}
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191
192void delete_from_swap_cache(struct page *page)
193{
194 swp_entry_t entry;
195
196 entry.val = page_private(page);
197
198 spin_lock_irq(&swapper_space.tree_lock);
199 __delete_from_swap_cache(page);
200 spin_unlock_irq(&swapper_space.tree_lock);
201
202 swapcache_free(entry, page);
203 page_cache_release(page);
204}
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213
214static inline void free_swap_cache(struct page *page)
215{
216 if (PageSwapCache(page) && !page_mapped(page) && trylock_page(page)) {
217 try_to_free_swap(page);
218 unlock_page(page);
219 }
220}
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225
226void free_page_and_swap_cache(struct page *page)
227{
228 free_swap_cache(page);
229 page_cache_release(page);
230}
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235
236void free_pages_and_swap_cache(struct page **pages, int nr)
237{
238 struct page **pagep = pages;
239
240 lru_add_drain();
241 while (nr) {
242 int todo = min(nr, PAGEVEC_SIZE);
243 int i;
244
245 for (i = 0; i < todo; i++)
246 free_swap_cache(pagep[i]);
247 release_pages(pagep, todo, 0);
248 pagep += todo;
249 nr -= todo;
250 }
251}
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259struct page * lookup_swap_cache(swp_entry_t entry)
260{
261 struct page *page;
262
263 page = find_get_page(&swapper_space, entry.val);
264
265 if (page)
266 INC_CACHE_INFO(find_success);
267
268 INC_CACHE_INFO(find_total);
269 return page;
270}
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278struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
279 struct vm_area_struct *vma, unsigned long addr)
280{
281 struct page *found_page, *new_page = NULL;
282 int err;
283
284 do {
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290 found_page = find_get_page(&swapper_space, entry.val);
291 if (found_page)
292 break;
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297 if (!new_page) {
298 new_page = alloc_page_vma(gfp_mask, vma, addr);
299 if (!new_page)
300 break;
301 }
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306 err = radix_tree_preload(gfp_mask & GFP_KERNEL);
307 if (err)
308 break;
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313 err = swapcache_prepare(entry);
314 if (err == -EEXIST) {
315 radix_tree_preload_end();
316 continue;
317 }
318 if (err) {
319 radix_tree_preload_end();
320 break;
321 }
322
323
324 __set_page_locked(new_page);
325 SetPageSwapBacked(new_page);
326 err = __add_to_swap_cache(new_page, entry);
327 if (likely(!err)) {
328 radix_tree_preload_end();
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332 lru_cache_add_anon(new_page);
333 swap_readpage(new_page);
334 return new_page;
335 }
336 radix_tree_preload_end();
337 ClearPageSwapBacked(new_page);
338 __clear_page_locked(new_page);
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343 swapcache_free(entry, NULL);
344 } while (err != -ENOMEM);
345
346 if (new_page)
347 page_cache_release(new_page);
348 return found_page;
349}
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370struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
371 struct vm_area_struct *vma, unsigned long addr)
372{
373 int nr_pages;
374 struct page *page;
375 unsigned long offset;
376 unsigned long end_offset;
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385 nr_pages = valid_swaphandles(entry, &offset);
386 for (end_offset = offset + nr_pages; offset < end_offset; offset++) {
387
388 page = read_swap_cache_async(swp_entry(swp_type(entry), offset),
389 gfp_mask, vma, addr);
390 if (!page)
391 break;
392 page_cache_release(page);
393 }
394 lru_add_drain();
395 return read_swap_cache_async(entry, gfp_mask, vma, addr);
396}
397