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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/swap_state.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * Swap reorganised 29.12.95, Stephen Tweedie | |
6 | * | |
7 | * Rewritten to use page cache, (C) 1998 Stephen Tweedie | |
8 | */ | |
1da177e4 | 9 | #include <linux/mm.h> |
5a0e3ad6 | 10 | #include <linux/gfp.h> |
1da177e4 LT |
11 | #include <linux/kernel_stat.h> |
12 | #include <linux/swap.h> | |
46017e95 | 13 | #include <linux/swapops.h> |
1da177e4 LT |
14 | #include <linux/init.h> |
15 | #include <linux/pagemap.h> | |
1da177e4 | 16 | #include <linux/backing-dev.h> |
3fb5c298 | 17 | #include <linux/blkdev.h> |
c484d410 | 18 | #include <linux/pagevec.h> |
b20a3503 | 19 | #include <linux/migrate.h> |
4b3ef9da | 20 | #include <linux/vmalloc.h> |
67afa38e | 21 | #include <linux/swap_slots.h> |
38d8b4e6 | 22 | #include <linux/huge_mm.h> |
1da177e4 LT |
23 | |
24 | #include <asm/pgtable.h> | |
25 | ||
26 | /* | |
27 | * swapper_space is a fiction, retained to simplify the path through | |
7eaceacc | 28 | * vmscan's shrink_page_list. |
1da177e4 | 29 | */ |
f5e54d6e | 30 | static const struct address_space_operations swap_aops = { |
1da177e4 | 31 | .writepage = swap_writepage, |
62c230bc | 32 | .set_page_dirty = swap_set_page_dirty, |
1c93923c | 33 | #ifdef CONFIG_MIGRATION |
e965f963 | 34 | .migratepage = migrate_page, |
1c93923c | 35 | #endif |
1da177e4 LT |
36 | }; |
37 | ||
4b3ef9da HY |
38 | struct address_space *swapper_spaces[MAX_SWAPFILES]; |
39 | static unsigned int nr_swapper_spaces[MAX_SWAPFILES]; | |
1da177e4 LT |
40 | |
41 | #define INC_CACHE_INFO(x) do { swap_cache_info.x++; } while (0) | |
38d8b4e6 | 42 | #define ADD_CACHE_INFO(x, nr) do { swap_cache_info.x += (nr); } while (0) |
1da177e4 LT |
43 | |
44 | static struct { | |
45 | unsigned long add_total; | |
46 | unsigned long del_total; | |
47 | unsigned long find_success; | |
48 | unsigned long find_total; | |
1da177e4 LT |
49 | } swap_cache_info; |
50 | ||
33806f06 SL |
51 | unsigned long total_swapcache_pages(void) |
52 | { | |
4b3ef9da | 53 | unsigned int i, j, nr; |
33806f06 | 54 | unsigned long ret = 0; |
4b3ef9da | 55 | struct address_space *spaces; |
33806f06 | 56 | |
4b3ef9da HY |
57 | rcu_read_lock(); |
58 | for (i = 0; i < MAX_SWAPFILES; i++) { | |
59 | /* | |
60 | * The corresponding entries in nr_swapper_spaces and | |
61 | * swapper_spaces will be reused only after at least | |
62 | * one grace period. So it is impossible for them | |
63 | * belongs to different usage. | |
64 | */ | |
65 | nr = nr_swapper_spaces[i]; | |
66 | spaces = rcu_dereference(swapper_spaces[i]); | |
67 | if (!nr || !spaces) | |
68 | continue; | |
69 | for (j = 0; j < nr; j++) | |
70 | ret += spaces[j].nrpages; | |
71 | } | |
72 | rcu_read_unlock(); | |
33806f06 SL |
73 | return ret; |
74 | } | |
75 | ||
579f8290 SL |
76 | static atomic_t swapin_readahead_hits = ATOMIC_INIT(4); |
77 | ||
1da177e4 LT |
78 | void show_swap_cache_info(void) |
79 | { | |
33806f06 | 80 | printk("%lu pages in swap cache\n", total_swapcache_pages()); |
2c97b7fc | 81 | printk("Swap cache stats: add %lu, delete %lu, find %lu/%lu\n", |
1da177e4 | 82 | swap_cache_info.add_total, swap_cache_info.del_total, |
bb63be0a | 83 | swap_cache_info.find_success, swap_cache_info.find_total); |
ec8acf20 SL |
84 | printk("Free swap = %ldkB\n", |
85 | get_nr_swap_pages() << (PAGE_SHIFT - 10)); | |
1da177e4 LT |
86 | printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10)); |
87 | } | |
88 | ||
89 | /* | |
31a56396 | 90 | * __add_to_swap_cache resembles add_to_page_cache_locked on swapper_space, |
1da177e4 LT |
91 | * but sets SwapCache flag and private instead of mapping and index. |
92 | */ | |
2f772e6c | 93 | int __add_to_swap_cache(struct page *page, swp_entry_t entry) |
1da177e4 | 94 | { |
38d8b4e6 | 95 | int error, i, nr = hpage_nr_pages(page); |
33806f06 | 96 | struct address_space *address_space; |
38d8b4e6 | 97 | pgoff_t idx = swp_offset(entry); |
1da177e4 | 98 | |
309381fe SL |
99 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
100 | VM_BUG_ON_PAGE(PageSwapCache(page), page); | |
101 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
51726b12 | 102 | |
38d8b4e6 | 103 | page_ref_add(page, nr); |
31a56396 | 104 | SetPageSwapCache(page); |
31a56396 | 105 | |
33806f06 SL |
106 | address_space = swap_address_space(entry); |
107 | spin_lock_irq(&address_space->tree_lock); | |
38d8b4e6 HY |
108 | for (i = 0; i < nr; i++) { |
109 | set_page_private(page + i, entry.val + i); | |
110 | error = radix_tree_insert(&address_space->page_tree, | |
111 | idx + i, page + i); | |
112 | if (unlikely(error)) | |
113 | break; | |
31a56396 | 114 | } |
38d8b4e6 HY |
115 | if (likely(!error)) { |
116 | address_space->nrpages += nr; | |
117 | __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr); | |
118 | ADD_CACHE_INFO(add_total, nr); | |
119 | } else { | |
2ca4532a DN |
120 | /* |
121 | * Only the context which have set SWAP_HAS_CACHE flag | |
122 | * would call add_to_swap_cache(). | |
123 | * So add_to_swap_cache() doesn't returns -EEXIST. | |
124 | */ | |
125 | VM_BUG_ON(error == -EEXIST); | |
38d8b4e6 HY |
126 | set_page_private(page + i, 0UL); |
127 | while (i--) { | |
128 | radix_tree_delete(&address_space->page_tree, idx + i); | |
129 | set_page_private(page + i, 0UL); | |
130 | } | |
31a56396 | 131 | ClearPageSwapCache(page); |
38d8b4e6 | 132 | page_ref_sub(page, nr); |
31a56396 | 133 | } |
38d8b4e6 | 134 | spin_unlock_irq(&address_space->tree_lock); |
31a56396 DN |
135 | |
136 | return error; | |
137 | } | |
138 | ||
139 | ||
140 | int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask) | |
141 | { | |
142 | int error; | |
143 | ||
38d8b4e6 | 144 | error = radix_tree_maybe_preload_order(gfp_mask, compound_order(page)); |
35c754d7 | 145 | if (!error) { |
31a56396 | 146 | error = __add_to_swap_cache(page, entry); |
1da177e4 | 147 | radix_tree_preload_end(); |
fa1de900 | 148 | } |
1da177e4 LT |
149 | return error; |
150 | } | |
151 | ||
1da177e4 LT |
152 | /* |
153 | * This must be called only on pages that have | |
154 | * been verified to be in the swap cache. | |
155 | */ | |
156 | void __delete_from_swap_cache(struct page *page) | |
157 | { | |
33806f06 | 158 | struct address_space *address_space; |
38d8b4e6 HY |
159 | int i, nr = hpage_nr_pages(page); |
160 | swp_entry_t entry; | |
161 | pgoff_t idx; | |
33806f06 | 162 | |
309381fe SL |
163 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
164 | VM_BUG_ON_PAGE(!PageSwapCache(page), page); | |
165 | VM_BUG_ON_PAGE(PageWriteback(page), page); | |
1da177e4 | 166 | |
33806f06 SL |
167 | entry.val = page_private(page); |
168 | address_space = swap_address_space(entry); | |
38d8b4e6 HY |
169 | idx = swp_offset(entry); |
170 | for (i = 0; i < nr; i++) { | |
171 | radix_tree_delete(&address_space->page_tree, idx + i); | |
172 | set_page_private(page + i, 0); | |
173 | } | |
1da177e4 | 174 | ClearPageSwapCache(page); |
38d8b4e6 HY |
175 | address_space->nrpages -= nr; |
176 | __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr); | |
177 | ADD_CACHE_INFO(del_total, nr); | |
1da177e4 LT |
178 | } |
179 | ||
180 | /** | |
181 | * add_to_swap - allocate swap space for a page | |
182 | * @page: page we want to move to swap | |
183 | * | |
184 | * Allocate swap space for the page and add the page to the | |
185 | * swap cache. Caller needs to hold the page lock. | |
186 | */ | |
0f074658 | 187 | int add_to_swap(struct page *page) |
1da177e4 LT |
188 | { |
189 | swp_entry_t entry; | |
1da177e4 LT |
190 | int err; |
191 | ||
309381fe SL |
192 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
193 | VM_BUG_ON_PAGE(!PageUptodate(page), page); | |
1da177e4 | 194 | |
38d8b4e6 | 195 | entry = get_swap_page(page); |
2ca4532a | 196 | if (!entry.val) |
0f074658 MK |
197 | return 0; |
198 | ||
38d8b4e6 | 199 | if (mem_cgroup_try_charge_swap(page, entry)) |
0f074658 | 200 | goto fail; |
3f04f62f | 201 | |
2ca4532a DN |
202 | /* |
203 | * Radix-tree node allocations from PF_MEMALLOC contexts could | |
204 | * completely exhaust the page allocator. __GFP_NOMEMALLOC | |
205 | * stops emergency reserves from being allocated. | |
206 | * | |
207 | * TODO: this could cause a theoretical memory reclaim | |
208 | * deadlock in the swap out path. | |
209 | */ | |
210 | /* | |
854e9ed0 | 211 | * Add it to the swap cache. |
2ca4532a DN |
212 | */ |
213 | err = add_to_swap_cache(page, entry, | |
214 | __GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN); | |
38d8b4e6 HY |
215 | /* -ENOMEM radix-tree allocation failure */ |
216 | if (err) | |
bd53b714 | 217 | /* |
2ca4532a DN |
218 | * add_to_swap_cache() doesn't return -EEXIST, so we can safely |
219 | * clear SWAP_HAS_CACHE flag. | |
1da177e4 | 220 | */ |
0f074658 | 221 | goto fail; |
38d8b4e6 HY |
222 | |
223 | return 1; | |
224 | ||
38d8b4e6 | 225 | fail: |
0f074658 | 226 | put_swap_page(page, entry); |
38d8b4e6 | 227 | return 0; |
1da177e4 LT |
228 | } |
229 | ||
230 | /* | |
231 | * This must be called only on pages that have | |
232 | * been verified to be in the swap cache and locked. | |
233 | * It will never put the page into the free list, | |
234 | * the caller has a reference on the page. | |
235 | */ | |
236 | void delete_from_swap_cache(struct page *page) | |
237 | { | |
238 | swp_entry_t entry; | |
33806f06 | 239 | struct address_space *address_space; |
1da177e4 | 240 | |
4c21e2f2 | 241 | entry.val = page_private(page); |
1da177e4 | 242 | |
33806f06 SL |
243 | address_space = swap_address_space(entry); |
244 | spin_lock_irq(&address_space->tree_lock); | |
1da177e4 | 245 | __delete_from_swap_cache(page); |
33806f06 | 246 | spin_unlock_irq(&address_space->tree_lock); |
1da177e4 | 247 | |
75f6d6d2 | 248 | put_swap_page(page, entry); |
38d8b4e6 | 249 | page_ref_sub(page, hpage_nr_pages(page)); |
1da177e4 LT |
250 | } |
251 | ||
1da177e4 LT |
252 | /* |
253 | * If we are the only user, then try to free up the swap cache. | |
254 | * | |
255 | * Its ok to check for PageSwapCache without the page lock | |
a2c43eed HD |
256 | * here because we are going to recheck again inside |
257 | * try_to_free_swap() _with_ the lock. | |
1da177e4 LT |
258 | * - Marcelo |
259 | */ | |
260 | static inline void free_swap_cache(struct page *page) | |
261 | { | |
a2c43eed HD |
262 | if (PageSwapCache(page) && !page_mapped(page) && trylock_page(page)) { |
263 | try_to_free_swap(page); | |
1da177e4 LT |
264 | unlock_page(page); |
265 | } | |
266 | } | |
267 | ||
268 | /* | |
269 | * Perform a free_page(), also freeing any swap cache associated with | |
b8072f09 | 270 | * this page if it is the last user of the page. |
1da177e4 LT |
271 | */ |
272 | void free_page_and_swap_cache(struct page *page) | |
273 | { | |
274 | free_swap_cache(page); | |
6fcb52a5 | 275 | if (!is_huge_zero_page(page)) |
770a5370 | 276 | put_page(page); |
1da177e4 LT |
277 | } |
278 | ||
279 | /* | |
280 | * Passed an array of pages, drop them all from swapcache and then release | |
281 | * them. They are removed from the LRU and freed if this is their last use. | |
282 | */ | |
283 | void free_pages_and_swap_cache(struct page **pages, int nr) | |
284 | { | |
1da177e4 | 285 | struct page **pagep = pages; |
aabfb572 | 286 | int i; |
1da177e4 LT |
287 | |
288 | lru_add_drain(); | |
aabfb572 MH |
289 | for (i = 0; i < nr; i++) |
290 | free_swap_cache(pagep[i]); | |
291 | release_pages(pagep, nr, false); | |
1da177e4 LT |
292 | } |
293 | ||
294 | /* | |
295 | * Lookup a swap entry in the swap cache. A found page will be returned | |
296 | * unlocked and with its refcount incremented - we rely on the kernel | |
297 | * lock getting page table operations atomic even if we drop the page | |
298 | * lock before returning. | |
299 | */ | |
300 | struct page * lookup_swap_cache(swp_entry_t entry) | |
301 | { | |
302 | struct page *page; | |
303 | ||
f6ab1f7f | 304 | page = find_get_page(swap_address_space(entry), swp_offset(entry)); |
1da177e4 | 305 | |
38d8b4e6 | 306 | if (page && likely(!PageTransCompound(page))) { |
1da177e4 | 307 | INC_CACHE_INFO(find_success); |
579f8290 SL |
308 | if (TestClearPageReadahead(page)) |
309 | atomic_inc(&swapin_readahead_hits); | |
310 | } | |
1da177e4 LT |
311 | |
312 | INC_CACHE_INFO(find_total); | |
313 | return page; | |
314 | } | |
315 | ||
5b999aad DS |
316 | struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, |
317 | struct vm_area_struct *vma, unsigned long addr, | |
318 | bool *new_page_allocated) | |
1da177e4 LT |
319 | { |
320 | struct page *found_page, *new_page = NULL; | |
5b999aad | 321 | struct address_space *swapper_space = swap_address_space(entry); |
1da177e4 | 322 | int err; |
5b999aad | 323 | *new_page_allocated = false; |
1da177e4 LT |
324 | |
325 | do { | |
326 | /* | |
327 | * First check the swap cache. Since this is normally | |
328 | * called after lookup_swap_cache() failed, re-calling | |
329 | * that would confuse statistics. | |
330 | */ | |
f6ab1f7f | 331 | found_page = find_get_page(swapper_space, swp_offset(entry)); |
1da177e4 LT |
332 | if (found_page) |
333 | break; | |
334 | ||
ba81f838 HY |
335 | /* |
336 | * Just skip read ahead for unused swap slot. | |
337 | * During swap_off when swap_slot_cache is disabled, | |
338 | * we have to handle the race between putting | |
339 | * swap entry in swap cache and marking swap slot | |
340 | * as SWAP_HAS_CACHE. That's done in later part of code or | |
341 | * else swap_off will be aborted if we return NULL. | |
342 | */ | |
343 | if (!__swp_swapcount(entry) && swap_slot_cache_enabled) | |
344 | break; | |
e8c26ab6 | 345 | |
1da177e4 LT |
346 | /* |
347 | * Get a new page to read into from swap. | |
348 | */ | |
349 | if (!new_page) { | |
02098fea | 350 | new_page = alloc_page_vma(gfp_mask, vma, addr); |
1da177e4 LT |
351 | if (!new_page) |
352 | break; /* Out of memory */ | |
353 | } | |
354 | ||
31a56396 DN |
355 | /* |
356 | * call radix_tree_preload() while we can wait. | |
357 | */ | |
5e4c0d97 | 358 | err = radix_tree_maybe_preload(gfp_mask & GFP_KERNEL); |
31a56396 DN |
359 | if (err) |
360 | break; | |
361 | ||
f000944d HD |
362 | /* |
363 | * Swap entry may have been freed since our caller observed it. | |
364 | */ | |
355cfa73 | 365 | err = swapcache_prepare(entry); |
cbab0e4e | 366 | if (err == -EEXIST) { |
31a56396 | 367 | radix_tree_preload_end(); |
cbab0e4e RA |
368 | /* |
369 | * We might race against get_swap_page() and stumble | |
370 | * across a SWAP_HAS_CACHE swap_map entry whose page | |
9c1cc2e4 | 371 | * has not been brought into the swapcache yet. |
cbab0e4e RA |
372 | */ |
373 | cond_resched(); | |
355cfa73 | 374 | continue; |
31a56396 DN |
375 | } |
376 | if (err) { /* swp entry is obsolete ? */ | |
377 | radix_tree_preload_end(); | |
f000944d | 378 | break; |
31a56396 | 379 | } |
f000944d | 380 | |
2ca4532a | 381 | /* May fail (-ENOMEM) if radix-tree node allocation failed. */ |
48c935ad | 382 | __SetPageLocked(new_page); |
fa9949da | 383 | __SetPageSwapBacked(new_page); |
31a56396 | 384 | err = __add_to_swap_cache(new_page, entry); |
529ae9aa | 385 | if (likely(!err)) { |
31a56396 | 386 | radix_tree_preload_end(); |
1da177e4 LT |
387 | /* |
388 | * Initiate read into locked page and return. | |
389 | */ | |
c5fdae46 | 390 | lru_cache_add_anon(new_page); |
5b999aad | 391 | *new_page_allocated = true; |
1da177e4 LT |
392 | return new_page; |
393 | } | |
31a56396 | 394 | radix_tree_preload_end(); |
48c935ad | 395 | __ClearPageLocked(new_page); |
2ca4532a DN |
396 | /* |
397 | * add_to_swap_cache() doesn't return -EEXIST, so we can safely | |
398 | * clear SWAP_HAS_CACHE flag. | |
399 | */ | |
75f6d6d2 | 400 | put_swap_page(new_page, entry); |
f000944d | 401 | } while (err != -ENOMEM); |
1da177e4 LT |
402 | |
403 | if (new_page) | |
09cbfeaf | 404 | put_page(new_page); |
1da177e4 LT |
405 | return found_page; |
406 | } | |
46017e95 | 407 | |
5b999aad DS |
408 | /* |
409 | * Locate a page of swap in physical memory, reserving swap cache space | |
410 | * and reading the disk if it is not already cached. | |
411 | * A failure return means that either the page allocation failed or that | |
412 | * the swap entry is no longer in use. | |
413 | */ | |
414 | struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, | |
23955622 | 415 | struct vm_area_struct *vma, unsigned long addr, bool do_poll) |
5b999aad DS |
416 | { |
417 | bool page_was_allocated; | |
418 | struct page *retpage = __read_swap_cache_async(entry, gfp_mask, | |
419 | vma, addr, &page_was_allocated); | |
420 | ||
421 | if (page_was_allocated) | |
23955622 | 422 | swap_readpage(retpage, do_poll); |
5b999aad DS |
423 | |
424 | return retpage; | |
425 | } | |
426 | ||
579f8290 SL |
427 | static unsigned long swapin_nr_pages(unsigned long offset) |
428 | { | |
429 | static unsigned long prev_offset; | |
430 | unsigned int pages, max_pages, last_ra; | |
431 | static atomic_t last_readahead_pages; | |
432 | ||
4db0c3c2 | 433 | max_pages = 1 << READ_ONCE(page_cluster); |
579f8290 SL |
434 | if (max_pages <= 1) |
435 | return 1; | |
436 | ||
437 | /* | |
438 | * This heuristic has been found to work well on both sequential and | |
439 | * random loads, swapping to hard disk or to SSD: please don't ask | |
440 | * what the "+ 2" means, it just happens to work well, that's all. | |
441 | */ | |
442 | pages = atomic_xchg(&swapin_readahead_hits, 0) + 2; | |
443 | if (pages == 2) { | |
444 | /* | |
445 | * We can have no readahead hits to judge by: but must not get | |
446 | * stuck here forever, so check for an adjacent offset instead | |
447 | * (and don't even bother to check whether swap type is same). | |
448 | */ | |
449 | if (offset != prev_offset + 1 && offset != prev_offset - 1) | |
450 | pages = 1; | |
451 | prev_offset = offset; | |
452 | } else { | |
453 | unsigned int roundup = 4; | |
454 | while (roundup < pages) | |
455 | roundup <<= 1; | |
456 | pages = roundup; | |
457 | } | |
458 | ||
459 | if (pages > max_pages) | |
460 | pages = max_pages; | |
461 | ||
462 | /* Don't shrink readahead too fast */ | |
463 | last_ra = atomic_read(&last_readahead_pages) / 2; | |
464 | if (pages < last_ra) | |
465 | pages = last_ra; | |
466 | atomic_set(&last_readahead_pages, pages); | |
467 | ||
468 | return pages; | |
469 | } | |
470 | ||
46017e95 HD |
471 | /** |
472 | * swapin_readahead - swap in pages in hope we need them soon | |
473 | * @entry: swap entry of this memory | |
7682486b | 474 | * @gfp_mask: memory allocation flags |
46017e95 HD |
475 | * @vma: user vma this address belongs to |
476 | * @addr: target address for mempolicy | |
477 | * | |
478 | * Returns the struct page for entry and addr, after queueing swapin. | |
479 | * | |
480 | * Primitive swap readahead code. We simply read an aligned block of | |
481 | * (1 << page_cluster) entries in the swap area. This method is chosen | |
482 | * because it doesn't cost us any seek time. We also make sure to queue | |
483 | * the 'original' request together with the readahead ones... | |
484 | * | |
485 | * This has been extended to use the NUMA policies from the mm triggering | |
486 | * the readahead. | |
487 | * | |
488 | * Caller must hold down_read on the vma->vm_mm if vma is not NULL. | |
489 | */ | |
02098fea | 490 | struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask, |
46017e95 HD |
491 | struct vm_area_struct *vma, unsigned long addr) |
492 | { | |
46017e95 | 493 | struct page *page; |
579f8290 SL |
494 | unsigned long entry_offset = swp_offset(entry); |
495 | unsigned long offset = entry_offset; | |
67f96aa2 | 496 | unsigned long start_offset, end_offset; |
579f8290 | 497 | unsigned long mask; |
3fb5c298 | 498 | struct blk_plug plug; |
23955622 | 499 | bool do_poll = true; |
46017e95 | 500 | |
579f8290 SL |
501 | mask = swapin_nr_pages(offset) - 1; |
502 | if (!mask) | |
503 | goto skip; | |
504 | ||
23955622 | 505 | do_poll = false; |
67f96aa2 RR |
506 | /* Read a page_cluster sized and aligned cluster around offset. */ |
507 | start_offset = offset & ~mask; | |
508 | end_offset = offset | mask; | |
509 | if (!start_offset) /* First page is swap header. */ | |
510 | start_offset++; | |
511 | ||
3fb5c298 | 512 | blk_start_plug(&plug); |
67f96aa2 | 513 | for (offset = start_offset; offset <= end_offset ; offset++) { |
46017e95 HD |
514 | /* Ok, do the async read-ahead now */ |
515 | page = read_swap_cache_async(swp_entry(swp_type(entry), offset), | |
23955622 | 516 | gfp_mask, vma, addr, false); |
46017e95 | 517 | if (!page) |
67f96aa2 | 518 | continue; |
38d8b4e6 | 519 | if (offset != entry_offset && likely(!PageTransCompound(page))) |
579f8290 | 520 | SetPageReadahead(page); |
09cbfeaf | 521 | put_page(page); |
46017e95 | 522 | } |
3fb5c298 CE |
523 | blk_finish_plug(&plug); |
524 | ||
46017e95 | 525 | lru_add_drain(); /* Push any new pages onto the LRU now */ |
579f8290 | 526 | skip: |
23955622 | 527 | return read_swap_cache_async(entry, gfp_mask, vma, addr, do_poll); |
46017e95 | 528 | } |
4b3ef9da HY |
529 | |
530 | int init_swap_address_space(unsigned int type, unsigned long nr_pages) | |
531 | { | |
532 | struct address_space *spaces, *space; | |
533 | unsigned int i, nr; | |
534 | ||
535 | nr = DIV_ROUND_UP(nr_pages, SWAP_ADDRESS_SPACE_PAGES); | |
54f180d3 | 536 | spaces = kvzalloc(sizeof(struct address_space) * nr, GFP_KERNEL); |
4b3ef9da HY |
537 | if (!spaces) |
538 | return -ENOMEM; | |
539 | for (i = 0; i < nr; i++) { | |
540 | space = spaces + i; | |
541 | INIT_RADIX_TREE(&space->page_tree, GFP_ATOMIC|__GFP_NOWARN); | |
542 | atomic_set(&space->i_mmap_writable, 0); | |
543 | space->a_ops = &swap_aops; | |
544 | /* swap cache doesn't use writeback related tags */ | |
545 | mapping_set_no_writeback_tags(space); | |
546 | spin_lock_init(&space->tree_lock); | |
547 | } | |
548 | nr_swapper_spaces[type] = nr; | |
549 | rcu_assign_pointer(swapper_spaces[type], spaces); | |
550 | ||
551 | return 0; | |
552 | } | |
553 | ||
554 | void exit_swap_address_space(unsigned int type) | |
555 | { | |
556 | struct address_space *spaces; | |
557 | ||
558 | spaces = swapper_spaces[type]; | |
559 | nr_swapper_spaces[type] = 0; | |
560 | rcu_assign_pointer(swapper_spaces[type], NULL); | |
561 | synchronize_rcu(); | |
562 | kvfree(spaces); | |
563 | } |