Root/
Source at commit b05a5adf03613de371c77c3235f7d970d7cd0c71 created 13 years 1 month ago. By Lars-Peter Clausen, NAND: Optimize reading the eec data for the JZ4740 (evil hack) | |
---|---|
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/mm.h> |
9 | #include <linux/hugetlb.h> |
10 | #include <linux/mman.h> |
11 | #include <linux/slab.h> |
12 | #include <linux/kernel_stat.h> |
13 | #include <linux/swap.h> |
14 | #include <linux/vmalloc.h> |
15 | #include <linux/pagemap.h> |
16 | #include <linux/namei.h> |
17 | #include <linux/shm.h> |
18 | #include <linux/blkdev.h> |
19 | #include <linux/random.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/ksm.h> |
26 | #include <linux/rmap.h> |
27 | #include <linux/security.h> |
28 | #include <linux/backing-dev.h> |
29 | #include <linux/mutex.h> |
30 | #include <linux/capability.h> |
31 | #include <linux/syscalls.h> |
32 | #include <linux/memcontrol.h> |
33 | #include <linux/poll.h> |
34 | |
35 | #include <asm/pgtable.h> |
36 | #include <asm/tlbflush.h> |
37 | #include <linux/swapops.h> |
38 | #include <linux/page_cgroup.h> |
39 | |
40 | static bool swap_count_continued(struct swap_info_struct *, pgoff_t, |
41 | unsigned char); |
42 | static void free_swap_count_continuations(struct swap_info_struct *); |
43 | static sector_t map_swap_entry(swp_entry_t, struct block_device**); |
44 | |
45 | static DEFINE_SPINLOCK(swap_lock); |
46 | static unsigned int nr_swapfiles; |
47 | long nr_swap_pages; |
48 | long total_swap_pages; |
49 | static int least_priority; |
50 | |
51 | static const char Bad_file[] = "Bad swap file entry "; |
52 | static const char Unused_file[] = "Unused swap file entry "; |
53 | static const char Bad_offset[] = "Bad swap offset entry "; |
54 | static const char Unused_offset[] = "Unused swap offset entry "; |
55 | |
56 | static struct swap_list_t swap_list = {-1, -1}; |
57 | |
58 | static struct swap_info_struct *swap_info[MAX_SWAPFILES]; |
59 | |
60 | static DEFINE_MUTEX(swapon_mutex); |
61 | |
62 | static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait); |
63 | /* Activity counter to indicate that a swapon or swapoff has occurred */ |
64 | static atomic_t proc_poll_event = ATOMIC_INIT(0); |
65 | |
66 | static inline unsigned char swap_count(unsigned char ent) |
67 | { |
68 | return ent & ~SWAP_HAS_CACHE; /* may include SWAP_HAS_CONT flag */ |
69 | } |
70 | |
71 | /* returns 1 if swap entry is freed */ |
72 | static int |
73 | __try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset) |
74 | { |
75 | swp_entry_t entry = swp_entry(si->type, offset); |
76 | struct page *page; |
77 | int ret = 0; |
78 | |
79 | page = find_get_page(&swapper_space, entry.val); |
80 | if (!page) |
81 | return 0; |
82 | /* |
83 | * This function is called from scan_swap_map() and it's called |
84 | * by vmscan.c at reclaiming pages. So, we hold a lock on a page, here. |
85 | * We have to use trylock for avoiding deadlock. This is a special |
86 | * case and you should use try_to_free_swap() with explicit lock_page() |
87 | * in usual operations. |
88 | */ |
89 | if (trylock_page(page)) { |
90 | ret = try_to_free_swap(page); |
91 | unlock_page(page); |
92 | } |
93 | page_cache_release(page); |
94 | return ret; |
95 | } |
96 | |
97 | /* |
98 | * swapon tell device that all the old swap contents can be discarded, |
99 | * to allow the swap device to optimize its wear-levelling. |
100 | */ |
101 | static int discard_swap(struct swap_info_struct *si) |
102 | { |
103 | struct swap_extent *se; |
104 | sector_t start_block; |
105 | sector_t nr_blocks; |
106 | int err = 0; |
107 | |
108 | /* Do not discard the swap header page! */ |
109 | se = &si->first_swap_extent; |
110 | start_block = (se->start_block + 1) << (PAGE_SHIFT - 9); |
111 | nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9); |
112 | if (nr_blocks) { |
113 | err = blkdev_issue_discard(si->bdev, start_block, |
114 | nr_blocks, GFP_KERNEL, 0); |
115 | if (err) |
116 | return err; |
117 | cond_resched(); |
118 | } |
119 | |
120 | list_for_each_entry(se, &si->first_swap_extent.list, list) { |
121 | start_block = se->start_block << (PAGE_SHIFT - 9); |
122 | nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); |
123 | |
124 | err = blkdev_issue_discard(si->bdev, start_block, |
125 | nr_blocks, GFP_KERNEL, 0); |
126 | if (err) |
127 | break; |
128 | |
129 | cond_resched(); |
130 | } |
131 | return err; /* That will often be -EOPNOTSUPP */ |
132 | } |
133 | |
134 | /* |
135 | * swap allocation tell device that a cluster of swap can now be discarded, |
136 | * to allow the swap device to optimize its wear-levelling. |
137 | */ |
138 | static void discard_swap_cluster(struct swap_info_struct *si, |
139 | pgoff_t start_page, pgoff_t nr_pages) |
140 | { |
141 | struct swap_extent *se = si->curr_swap_extent; |
142 | int found_extent = 0; |
143 | |
144 | while (nr_pages) { |
145 | struct list_head *lh; |
146 | |
147 | if (se->start_page <= start_page && |
148 | start_page < se->start_page + se->nr_pages) { |
149 | pgoff_t offset = start_page - se->start_page; |
150 | sector_t start_block = se->start_block + offset; |
151 | sector_t nr_blocks = se->nr_pages - offset; |
152 | |
153 | if (nr_blocks > nr_pages) |
154 | nr_blocks = nr_pages; |
155 | start_page += nr_blocks; |
156 | nr_pages -= nr_blocks; |
157 | |
158 | if (!found_extent++) |
159 | si->curr_swap_extent = se; |
160 | |
161 | start_block <<= PAGE_SHIFT - 9; |
162 | nr_blocks <<= PAGE_SHIFT - 9; |
163 | if (blkdev_issue_discard(si->bdev, start_block, |
164 | nr_blocks, GFP_NOIO, 0)) |
165 | break; |
166 | } |
167 | |
168 | lh = se->list.next; |
169 | se = list_entry(lh, struct swap_extent, list); |
170 | } |
171 | } |
172 | |
173 | static int wait_for_discard(void *word) |
174 | { |
175 | schedule(); |
176 | return 0; |
177 | } |
178 | |
179 | #define SWAPFILE_CLUSTER 256 |
180 | #define LATENCY_LIMIT 256 |
181 | |
182 | static unsigned long scan_swap_map(struct swap_info_struct *si, |
183 | unsigned char usage) |
184 | { |
185 | unsigned long offset; |
186 | unsigned long scan_base; |
187 | unsigned long last_in_cluster = 0; |
188 | int latency_ration = LATENCY_LIMIT; |
189 | int found_free_cluster = 0; |
190 | |
191 | /* |
192 | * We try to cluster swap pages by allocating them sequentially |
193 | * in swap. Once we've allocated SWAPFILE_CLUSTER pages this |
194 | * way, however, we resort to first-free allocation, starting |
195 | * a new cluster. This prevents us from scattering swap pages |
196 | * all over the entire swap partition, so that we reduce |
197 | * overall disk seek times between swap pages. -- sct |
198 | * But we do now try to find an empty cluster. -Andrea |
199 | * And we let swap pages go all over an SSD partition. Hugh |
200 | */ |
201 | |
202 | si->flags += SWP_SCANNING; |
203 | scan_base = offset = si->cluster_next; |
204 | |
205 | if (unlikely(!si->cluster_nr--)) { |
206 | if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { |
207 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
208 | goto checks; |
209 | } |
210 | if (si->flags & SWP_DISCARDABLE) { |
211 | /* |
212 | * Start range check on racing allocations, in case |
213 | * they overlap the cluster we eventually decide on |
214 | * (we scan without swap_lock to allow preemption). |
215 | * It's hardly conceivable that cluster_nr could be |
216 | * wrapped during our scan, but don't depend on it. |
217 | */ |
218 | if (si->lowest_alloc) |
219 | goto checks; |
220 | si->lowest_alloc = si->max; |
221 | si->highest_alloc = 0; |
222 | } |
223 | spin_unlock(&swap_lock); |
224 | |
225 | /* |
226 | * If seek is expensive, start searching for new cluster from |
227 | * start of partition, to minimize the span of allocated swap. |
228 | * But if seek is cheap, search from our current position, so |
229 | * that swap is allocated from all over the partition: if the |
230 | * Flash Translation Layer only remaps within limited zones, |
231 | * we don't want to wear out the first zone too quickly. |
232 | */ |
233 | if (!(si->flags & SWP_SOLIDSTATE)) |
234 | scan_base = offset = si->lowest_bit; |
235 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
236 | |
237 | /* Locate the first empty (unaligned) cluster */ |
238 | for (; last_in_cluster <= si->highest_bit; offset++) { |
239 | if (si->swap_map[offset]) |
240 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
241 | else if (offset == last_in_cluster) { |
242 | spin_lock(&swap_lock); |
243 | offset -= SWAPFILE_CLUSTER - 1; |
244 | si->cluster_next = offset; |
245 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
246 | found_free_cluster = 1; |
247 | goto checks; |
248 | } |
249 | if (unlikely(--latency_ration < 0)) { |
250 | cond_resched(); |
251 | latency_ration = LATENCY_LIMIT; |
252 | } |
253 | } |
254 | |
255 | offset = si->lowest_bit; |
256 | last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
257 | |
258 | /* Locate the first empty (unaligned) cluster */ |
259 | for (; last_in_cluster < scan_base; offset++) { |
260 | if (si->swap_map[offset]) |
261 | last_in_cluster = offset + SWAPFILE_CLUSTER; |
262 | else if (offset == last_in_cluster) { |
263 | spin_lock(&swap_lock); |
264 | offset -= SWAPFILE_CLUSTER - 1; |
265 | si->cluster_next = offset; |
266 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
267 | found_free_cluster = 1; |
268 | goto checks; |
269 | } |
270 | if (unlikely(--latency_ration < 0)) { |
271 | cond_resched(); |
272 | latency_ration = LATENCY_LIMIT; |
273 | } |
274 | } |
275 | |
276 | offset = scan_base; |
277 | spin_lock(&swap_lock); |
278 | si->cluster_nr = SWAPFILE_CLUSTER - 1; |
279 | si->lowest_alloc = 0; |
280 | } |
281 | |
282 | checks: |
283 | if (!(si->flags & SWP_WRITEOK)) |
284 | goto no_page; |
285 | if (!si->highest_bit) |
286 | goto no_page; |
287 | if (offset > si->highest_bit) |
288 | scan_base = offset = si->lowest_bit; |
289 | |
290 | /* reuse swap entry of cache-only swap if not busy. */ |
291 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
292 | int swap_was_freed; |
293 | spin_unlock(&swap_lock); |
294 | swap_was_freed = __try_to_reclaim_swap(si, offset); |
295 | spin_lock(&swap_lock); |
296 | /* entry was freed successfully, try to use this again */ |
297 | if (swap_was_freed) |
298 | goto checks; |
299 | goto scan; /* check next one */ |
300 | } |
301 | |
302 | if (si->swap_map[offset]) |
303 | goto scan; |
304 | |
305 | if (offset == si->lowest_bit) |
306 | si->lowest_bit++; |
307 | if (offset == si->highest_bit) |
308 | si->highest_bit--; |
309 | si->inuse_pages++; |
310 | if (si->inuse_pages == si->pages) { |
311 | si->lowest_bit = si->max; |
312 | si->highest_bit = 0; |
313 | } |
314 | si->swap_map[offset] = usage; |
315 | si->cluster_next = offset + 1; |
316 | si->flags -= SWP_SCANNING; |
317 | |
318 | if (si->lowest_alloc) { |
319 | /* |
320 | * Only set when SWP_DISCARDABLE, and there's a scan |
321 | * for a free cluster in progress or just completed. |
322 | */ |
323 | if (found_free_cluster) { |
324 | /* |
325 | * To optimize wear-levelling, discard the |
326 | * old data of the cluster, taking care not to |
327 | * discard any of its pages that have already |
328 | * been allocated by racing tasks (offset has |
329 | * already stepped over any at the beginning). |
330 | */ |
331 | if (offset < si->highest_alloc && |
332 | si->lowest_alloc <= last_in_cluster) |
333 | last_in_cluster = si->lowest_alloc - 1; |
334 | si->flags |= SWP_DISCARDING; |
335 | spin_unlock(&swap_lock); |
336 | |
337 | if (offset < last_in_cluster) |
338 | discard_swap_cluster(si, offset, |
339 | last_in_cluster - offset + 1); |
340 | |
341 | spin_lock(&swap_lock); |
342 | si->lowest_alloc = 0; |
343 | si->flags &= ~SWP_DISCARDING; |
344 | |
345 | smp_mb(); /* wake_up_bit advises this */ |
346 | wake_up_bit(&si->flags, ilog2(SWP_DISCARDING)); |
347 | |
348 | } else if (si->flags & SWP_DISCARDING) { |
349 | /* |
350 | * Delay using pages allocated by racing tasks |
351 | * until the whole discard has been issued. We |
352 | * could defer that delay until swap_writepage, |
353 | * but it's easier to keep this self-contained. |
354 | */ |
355 | spin_unlock(&swap_lock); |
356 | wait_on_bit(&si->flags, ilog2(SWP_DISCARDING), |
357 | wait_for_discard, TASK_UNINTERRUPTIBLE); |
358 | spin_lock(&swap_lock); |
359 | } else { |
360 | /* |
361 | * Note pages allocated by racing tasks while |
362 | * scan for a free cluster is in progress, so |
363 | * that its final discard can exclude them. |
364 | */ |
365 | if (offset < si->lowest_alloc) |
366 | si->lowest_alloc = offset; |
367 | if (offset > si->highest_alloc) |
368 | si->highest_alloc = offset; |
369 | } |
370 | } |
371 | return offset; |
372 | |
373 | scan: |
374 | spin_unlock(&swap_lock); |
375 | while (++offset <= si->highest_bit) { |
376 | if (!si->swap_map[offset]) { |
377 | spin_lock(&swap_lock); |
378 | goto checks; |
379 | } |
380 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
381 | spin_lock(&swap_lock); |
382 | goto checks; |
383 | } |
384 | if (unlikely(--latency_ration < 0)) { |
385 | cond_resched(); |
386 | latency_ration = LATENCY_LIMIT; |
387 | } |
388 | } |
389 | offset = si->lowest_bit; |
390 | while (++offset < scan_base) { |
391 | if (!si->swap_map[offset]) { |
392 | spin_lock(&swap_lock); |
393 | goto checks; |
394 | } |
395 | if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
396 | spin_lock(&swap_lock); |
397 | goto checks; |
398 | } |
399 | if (unlikely(--latency_ration < 0)) { |
400 | cond_resched(); |
401 | latency_ration = LATENCY_LIMIT; |
402 | } |
403 | } |
404 | spin_lock(&swap_lock); |
405 | |
406 | no_page: |
407 | si->flags -= SWP_SCANNING; |
408 | return 0; |
409 | } |
410 | |
411 | swp_entry_t get_swap_page(void) |
412 | { |
413 | struct swap_info_struct *si; |
414 | pgoff_t offset; |
415 | int type, next; |
416 | int wrapped = 0; |
417 | |
418 | spin_lock(&swap_lock); |
419 | if (nr_swap_pages <= 0) |
420 | goto noswap; |
421 | nr_swap_pages--; |
422 | |
423 | for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) { |
424 | si = swap_info[type]; |
425 | next = si->next; |
426 | if (next < 0 || |
427 | (!wrapped && si->prio != swap_info[next]->prio)) { |
428 | next = swap_list.head; |
429 | wrapped++; |
430 | } |
431 | |
432 | if (!si->highest_bit) |
433 | continue; |
434 | if (!(si->flags & SWP_WRITEOK)) |
435 | continue; |
436 | |
437 | swap_list.next = next; |
438 | /* This is called for allocating swap entry for cache */ |
439 | offset = scan_swap_map(si, SWAP_HAS_CACHE); |
440 | if (offset) { |
441 | spin_unlock(&swap_lock); |
442 | return swp_entry(type, offset); |
443 | } |
444 | next = swap_list.next; |
445 | } |
446 | |
447 | nr_swap_pages++; |
448 | noswap: |
449 | spin_unlock(&swap_lock); |
450 | return (swp_entry_t) {0}; |
451 | } |
452 | |
453 | /* The only caller of this function is now susupend routine */ |
454 | swp_entry_t get_swap_page_of_type(int type) |
455 | { |
456 | struct swap_info_struct *si; |
457 | pgoff_t offset; |
458 | |
459 | spin_lock(&swap_lock); |
460 | si = swap_info[type]; |
461 | if (si && (si->flags & SWP_WRITEOK)) { |
462 | nr_swap_pages--; |
463 | /* This is called for allocating swap entry, not cache */ |
464 | offset = scan_swap_map(si, 1); |
465 | if (offset) { |
466 | spin_unlock(&swap_lock); |
467 | return swp_entry(type, offset); |
468 | } |
469 | nr_swap_pages++; |
470 | } |
471 | spin_unlock(&swap_lock); |
472 | return (swp_entry_t) {0}; |
473 | } |
474 | |
475 | static struct swap_info_struct *swap_info_get(swp_entry_t entry) |
476 | { |
477 | struct swap_info_struct *p; |
478 | unsigned long offset, type; |
479 | |
480 | if (!entry.val) |
481 | goto out; |
482 | type = swp_type(entry); |
483 | if (type >= nr_swapfiles) |
484 | goto bad_nofile; |
485 | p = swap_info[type]; |
486 | if (!(p->flags & SWP_USED)) |
487 | goto bad_device; |
488 | offset = swp_offset(entry); |
489 | if (offset >= p->max) |
490 | goto bad_offset; |
491 | if (!p->swap_map[offset]) |
492 | goto bad_free; |
493 | spin_lock(&swap_lock); |
494 | return p; |
495 | |
496 | bad_free: |
497 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val); |
498 | goto out; |
499 | bad_offset: |
500 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val); |
501 | goto out; |
502 | bad_device: |
503 | printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val); |
504 | goto out; |
505 | bad_nofile: |
506 | printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val); |
507 | out: |
508 | return NULL; |
509 | } |
510 | |
511 | static unsigned char swap_entry_free(struct swap_info_struct *p, |
512 | swp_entry_t entry, unsigned char usage) |
513 | { |
514 | unsigned long offset = swp_offset(entry); |
515 | unsigned char count; |
516 | unsigned char has_cache; |
517 | |
518 | count = p->swap_map[offset]; |
519 | has_cache = count & SWAP_HAS_CACHE; |
520 | count &= ~SWAP_HAS_CACHE; |
521 | |
522 | if (usage == SWAP_HAS_CACHE) { |
523 | VM_BUG_ON(!has_cache); |
524 | has_cache = 0; |
525 | } else if (count == SWAP_MAP_SHMEM) { |
526 | /* |
527 | * Or we could insist on shmem.c using a special |
528 | * swap_shmem_free() and free_shmem_swap_and_cache()... |
529 | */ |
530 | count = 0; |
531 | } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { |
532 | if (count == COUNT_CONTINUED) { |
533 | if (swap_count_continued(p, offset, count)) |
534 | count = SWAP_MAP_MAX | COUNT_CONTINUED; |
535 | else |
536 | count = SWAP_MAP_MAX; |
537 | } else |
538 | count--; |
539 | } |
540 | |
541 | if (!count) |
542 | mem_cgroup_uncharge_swap(entry); |
543 | |
544 | usage = count | has_cache; |
545 | p->swap_map[offset] = usage; |
546 | |
547 | /* free if no reference */ |
548 | if (!usage) { |
549 | struct gendisk *disk = p->bdev->bd_disk; |
550 | if (offset < p->lowest_bit) |
551 | p->lowest_bit = offset; |
552 | if (offset > p->highest_bit) |
553 | p->highest_bit = offset; |
554 | if (swap_list.next >= 0 && |
555 | p->prio > swap_info[swap_list.next]->prio) |
556 | swap_list.next = p->type; |
557 | nr_swap_pages++; |
558 | p->inuse_pages--; |
559 | if ((p->flags & SWP_BLKDEV) && |
560 | disk->fops->swap_slot_free_notify) |
561 | disk->fops->swap_slot_free_notify(p->bdev, offset); |
562 | } |
563 | |
564 | return usage; |
565 | } |
566 | |
567 | /* |
568 | * Caller has made sure that the swapdevice corresponding to entry |
569 | * is still around or has not been recycled. |
570 | */ |
571 | void swap_free(swp_entry_t entry) |
572 | { |
573 | struct swap_info_struct *p; |
574 | |
575 | p = swap_info_get(entry); |
576 | if (p) { |
577 | swap_entry_free(p, entry, 1); |
578 | spin_unlock(&swap_lock); |
579 | } |
580 | } |
581 | |
582 | /* |
583 | * Called after dropping swapcache to decrease refcnt to swap entries. |
584 | */ |
585 | void swapcache_free(swp_entry_t entry, struct page *page) |
586 | { |
587 | struct swap_info_struct *p; |
588 | unsigned char count; |
589 | |
590 | p = swap_info_get(entry); |
591 | if (p) { |
592 | count = swap_entry_free(p, entry, SWAP_HAS_CACHE); |
593 | if (page) |
594 | mem_cgroup_uncharge_swapcache(page, entry, count != 0); |
595 | spin_unlock(&swap_lock); |
596 | } |
597 | } |
598 | |
599 | /* |
600 | * How many references to page are currently swapped out? |
601 | * This does not give an exact answer when swap count is continued, |
602 | * but does include the high COUNT_CONTINUED flag to allow for that. |
603 | */ |
604 | static inline int page_swapcount(struct page *page) |
605 | { |
606 | int count = 0; |
607 | struct swap_info_struct *p; |
608 | swp_entry_t entry; |
609 | |
610 | entry.val = page_private(page); |
611 | p = swap_info_get(entry); |
612 | if (p) { |
613 | count = swap_count(p->swap_map[swp_offset(entry)]); |
614 | spin_unlock(&swap_lock); |
615 | } |
616 | return count; |
617 | } |
618 | |
619 | /* |
620 | * We can write to an anon page without COW if there are no other references |
621 | * to it. And as a side-effect, free up its swap: because the old content |
622 | * on disk will never be read, and seeking back there to write new content |
623 | * later would only waste time away from clustering. |
624 | */ |
625 | int reuse_swap_page(struct page *page) |
626 | { |
627 | int count; |
628 | |
629 | VM_BUG_ON(!PageLocked(page)); |
630 | if (unlikely(PageKsm(page))) |
631 | return 0; |
632 | count = page_mapcount(page); |
633 | if (count <= 1 && PageSwapCache(page)) { |
634 | count += page_swapcount(page); |
635 | if (count == 1 && !PageWriteback(page)) { |
636 | delete_from_swap_cache(page); |
637 | SetPageDirty(page); |
638 | } |
639 | } |
640 | return count <= 1; |
641 | } |
642 | |
643 | /* |
644 | * If swap is getting full, or if there are no more mappings of this page, |
645 | * then try_to_free_swap is called to free its swap space. |
646 | */ |
647 | int try_to_free_swap(struct page *page) |
648 | { |
649 | VM_BUG_ON(!PageLocked(page)); |
650 | |
651 | if (!PageSwapCache(page)) |
652 | return 0; |
653 | if (PageWriteback(page)) |
654 | return 0; |
655 | if (page_swapcount(page)) |
656 | return 0; |
657 | |
658 | /* |
659 | * Once hibernation has begun to create its image of memory, |
660 | * there's a danger that one of the calls to try_to_free_swap() |
661 | * - most probably a call from __try_to_reclaim_swap() while |
662 | * hibernation is allocating its own swap pages for the image, |
663 | * but conceivably even a call from memory reclaim - will free |
664 | * the swap from a page which has already been recorded in the |
665 | * image as a clean swapcache page, and then reuse its swap for |
666 | * another page of the image. On waking from hibernation, the |
667 | * original page might be freed under memory pressure, then |
668 | * later read back in from swap, now with the wrong data. |
669 | * |
670 | * Hibernation clears bits from gfp_allowed_mask to prevent |
671 | * memory reclaim from writing to disk, so check that here. |
672 | */ |
673 | if (!(gfp_allowed_mask & __GFP_IO)) |
674 | return 0; |
675 | |
676 | delete_from_swap_cache(page); |
677 | SetPageDirty(page); |
678 | return 1; |
679 | } |
680 | |
681 | /* |
682 | * Free the swap entry like above, but also try to |
683 | * free the page cache entry if it is the last user. |
684 | */ |
685 | int free_swap_and_cache(swp_entry_t entry) |
686 | { |
687 | struct swap_info_struct *p; |
688 | struct page *page = NULL; |
689 | |
690 | if (non_swap_entry(entry)) |
691 | return 1; |
692 | |
693 | p = swap_info_get(entry); |
694 | if (p) { |
695 | if (swap_entry_free(p, entry, 1) == SWAP_HAS_CACHE) { |
696 | page = find_get_page(&swapper_space, entry.val); |
697 | if (page && !trylock_page(page)) { |
698 | page_cache_release(page); |
699 | page = NULL; |
700 | } |
701 | } |
702 | spin_unlock(&swap_lock); |
703 | } |
704 | if (page) { |
705 | /* |
706 | * Not mapped elsewhere, or swap space full? Free it! |
707 | * Also recheck PageSwapCache now page is locked (above). |
708 | */ |
709 | if (PageSwapCache(page) && !PageWriteback(page) && |
710 | (!page_mapped(page) || vm_swap_full())) { |
711 | delete_from_swap_cache(page); |
712 | SetPageDirty(page); |
713 | } |
714 | unlock_page(page); |
715 | page_cache_release(page); |
716 | } |
717 | return p != NULL; |
718 | } |
719 | |
720 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
721 | /** |
722 | * mem_cgroup_count_swap_user - count the user of a swap entry |
723 | * @ent: the swap entry to be checked |
724 | * @pagep: the pointer for the swap cache page of the entry to be stored |
725 | * |
726 | * Returns the number of the user of the swap entry. The number is valid only |
727 | * for swaps of anonymous pages. |
728 | * If the entry is found on swap cache, the page is stored to pagep with |
729 | * refcount of it being incremented. |
730 | */ |
731 | int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep) |
732 | { |
733 | struct page *page; |
734 | struct swap_info_struct *p; |
735 | int count = 0; |
736 | |
737 | page = find_get_page(&swapper_space, ent.val); |
738 | if (page) |
739 | count += page_mapcount(page); |
740 | p = swap_info_get(ent); |
741 | if (p) { |
742 | count += swap_count(p->swap_map[swp_offset(ent)]); |
743 | spin_unlock(&swap_lock); |
744 | } |
745 | |
746 | *pagep = page; |
747 | return count; |
748 | } |
749 | #endif |
750 | |
751 | #ifdef CONFIG_HIBERNATION |
752 | /* |
753 | * Find the swap type that corresponds to given device (if any). |
754 | * |
755 | * @offset - number of the PAGE_SIZE-sized block of the device, starting |
756 | * from 0, in which the swap header is expected to be located. |
757 | * |
758 | * This is needed for the suspend to disk (aka swsusp). |
759 | */ |
760 | int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) |
761 | { |
762 | struct block_device *bdev = NULL; |
763 | int type; |
764 | |
765 | if (device) |
766 | bdev = bdget(device); |
767 | |
768 | spin_lock(&swap_lock); |
769 | for (type = 0; type < nr_swapfiles; type++) { |
770 | struct swap_info_struct *sis = swap_info[type]; |
771 | |
772 | if (!(sis->flags & SWP_WRITEOK)) |
773 | continue; |
774 | |
775 | if (!bdev) { |
776 | if (bdev_p) |
777 | *bdev_p = bdgrab(sis->bdev); |
778 | |
779 | spin_unlock(&swap_lock); |
780 | return type; |
781 | } |
782 | if (bdev == sis->bdev) { |
783 | struct swap_extent *se = &sis->first_swap_extent; |
784 | |
785 | if (se->start_block == offset) { |
786 | if (bdev_p) |
787 | *bdev_p = bdgrab(sis->bdev); |
788 | |
789 | spin_unlock(&swap_lock); |
790 | bdput(bdev); |
791 | return type; |
792 | } |
793 | } |
794 | } |
795 | spin_unlock(&swap_lock); |
796 | if (bdev) |
797 | bdput(bdev); |
798 | |
799 | return -ENODEV; |
800 | } |
801 | |
802 | /* |
803 | * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev |
804 | * corresponding to given index in swap_info (swap type). |
805 | */ |
806 | sector_t swapdev_block(int type, pgoff_t offset) |
807 | { |
808 | struct block_device *bdev; |
809 | |
810 | if ((unsigned int)type >= nr_swapfiles) |
811 | return 0; |
812 | if (!(swap_info[type]->flags & SWP_WRITEOK)) |
813 | return 0; |
814 | return map_swap_entry(swp_entry(type, offset), &bdev); |
815 | } |
816 | |
817 | /* |
818 | * Return either the total number of swap pages of given type, or the number |
819 | * of free pages of that type (depending on @free) |
820 | * |
821 | * This is needed for software suspend |
822 | */ |
823 | unsigned int count_swap_pages(int type, int free) |
824 | { |
825 | unsigned int n = 0; |
826 | |
827 | spin_lock(&swap_lock); |
828 | if ((unsigned int)type < nr_swapfiles) { |
829 | struct swap_info_struct *sis = swap_info[type]; |
830 | |
831 | if (sis->flags & SWP_WRITEOK) { |
832 | n = sis->pages; |
833 | if (free) |
834 | n -= sis->inuse_pages; |
835 | } |
836 | } |
837 | spin_unlock(&swap_lock); |
838 | return n; |
839 | } |
840 | #endif /* CONFIG_HIBERNATION */ |
841 | |
842 | /* |
843 | * No need to decide whether this PTE shares the swap entry with others, |
844 | * just let do_wp_page work it out if a write is requested later - to |
845 | * force COW, vm_page_prot omits write permission from any private vma. |
846 | */ |
847 | static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
848 | unsigned long addr, swp_entry_t entry, struct page *page) |
849 | { |
850 | struct mem_cgroup *ptr; |
851 | spinlock_t *ptl; |
852 | pte_t *pte; |
853 | int ret = 1; |
854 | |
855 | if (mem_cgroup_try_charge_swapin(vma->vm_mm, page, GFP_KERNEL, &ptr)) { |
856 | ret = -ENOMEM; |
857 | goto out_nolock; |
858 | } |
859 | |
860 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); |
861 | if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) { |
862 | if (ret > 0) |
863 | mem_cgroup_cancel_charge_swapin(ptr); |
864 | ret = 0; |
865 | goto out; |
866 | } |
867 | |
868 | dec_mm_counter(vma->vm_mm, MM_SWAPENTS); |
869 | inc_mm_counter(vma->vm_mm, MM_ANONPAGES); |
870 | get_page(page); |
871 | set_pte_at(vma->vm_mm, addr, pte, |
872 | pte_mkold(mk_pte(page, vma->vm_page_prot))); |
873 | page_add_anon_rmap(page, vma, addr); |
874 | mem_cgroup_commit_charge_swapin(page, ptr); |
875 | swap_free(entry); |
876 | /* |
877 | * Move the page to the active list so it is not |
878 | * immediately swapped out again after swapon. |
879 | */ |
880 | activate_page(page); |
881 | out: |
882 | pte_unmap_unlock(pte, ptl); |
883 | out_nolock: |
884 | return ret; |
885 | } |
886 | |
887 | static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, |
888 | unsigned long addr, unsigned long end, |
889 | swp_entry_t entry, struct page *page) |
890 | { |
891 | pte_t swp_pte = swp_entry_to_pte(entry); |
892 | pte_t *pte; |
893 | int ret = 0; |
894 | |
895 | /* |
896 | * We don't actually need pte lock while scanning for swp_pte: since |
897 | * we hold page lock and mmap_sem, swp_pte cannot be inserted into the |
898 | * page table while we're scanning; though it could get zapped, and on |
899 | * some architectures (e.g. x86_32 with PAE) we might catch a glimpse |
900 | * of unmatched parts which look like swp_pte, so unuse_pte must |
901 | * recheck under pte lock. Scanning without pte lock lets it be |
902 | * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE. |
903 | */ |
904 | pte = pte_offset_map(pmd, addr); |
905 | do { |
906 | /* |
907 | * swapoff spends a _lot_ of time in this loop! |
908 | * Test inline before going to call unuse_pte. |
909 | */ |
910 | if (unlikely(pte_same(*pte, swp_pte))) { |
911 | pte_unmap(pte); |
912 | ret = unuse_pte(vma, pmd, addr, entry, page); |
913 | if (ret) |
914 | goto out; |
915 | pte = pte_offset_map(pmd, addr); |
916 | } |
917 | } while (pte++, addr += PAGE_SIZE, addr != end); |
918 | pte_unmap(pte - 1); |
919 | out: |
920 | return ret; |
921 | } |
922 | |
923 | static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, |
924 | unsigned long addr, unsigned long end, |
925 | swp_entry_t entry, struct page *page) |
926 | { |
927 | pmd_t *pmd; |
928 | unsigned long next; |
929 | int ret; |
930 | |
931 | pmd = pmd_offset(pud, addr); |
932 | do { |
933 | next = pmd_addr_end(addr, end); |
934 | if (unlikely(pmd_trans_huge(*pmd))) |
935 | continue; |
936 | if (pmd_none_or_clear_bad(pmd)) |
937 | continue; |
938 | ret = unuse_pte_range(vma, pmd, addr, next, entry, page); |
939 | if (ret) |
940 | return ret; |
941 | } while (pmd++, addr = next, addr != end); |
942 | return 0; |
943 | } |
944 | |
945 | static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd, |
946 | unsigned long addr, unsigned long end, |
947 | swp_entry_t entry, struct page *page) |
948 | { |
949 | pud_t *pud; |
950 | unsigned long next; |
951 | int ret; |
952 | |
953 | pud = pud_offset(pgd, addr); |
954 | do { |
955 | next = pud_addr_end(addr, end); |
956 | if (pud_none_or_clear_bad(pud)) |
957 | continue; |
958 | ret = unuse_pmd_range(vma, pud, addr, next, entry, page); |
959 | if (ret) |
960 | return ret; |
961 | } while (pud++, addr = next, addr != end); |
962 | return 0; |
963 | } |
964 | |
965 | static int unuse_vma(struct vm_area_struct *vma, |
966 | swp_entry_t entry, struct page *page) |
967 | { |
968 | pgd_t *pgd; |
969 | unsigned long addr, end, next; |
970 | int ret; |
971 | |
972 | if (page_anon_vma(page)) { |
973 | addr = page_address_in_vma(page, vma); |
974 | if (addr == -EFAULT) |
975 | return 0; |
976 | else |
977 | end = addr + PAGE_SIZE; |
978 | } else { |
979 | addr = vma->vm_start; |
980 | end = vma->vm_end; |
981 | } |
982 | |
983 | pgd = pgd_offset(vma->vm_mm, addr); |
984 | do { |
985 | next = pgd_addr_end(addr, end); |
986 | if (pgd_none_or_clear_bad(pgd)) |
987 | continue; |
988 | ret = unuse_pud_range(vma, pgd, addr, next, entry, page); |
989 | if (ret) |
990 | return ret; |
991 | } while (pgd++, addr = next, addr != end); |
992 | return 0; |
993 | } |
994 | |
995 | static int unuse_mm(struct mm_struct *mm, |
996 | swp_entry_t entry, struct page *page) |
997 | { |
998 | struct vm_area_struct *vma; |
999 | int ret = 0; |
1000 | |
1001 | if (!down_read_trylock(&mm->mmap_sem)) { |
1002 | /* |
1003 | * Activate page so shrink_inactive_list is unlikely to unmap |
1004 | * its ptes while lock is dropped, so swapoff can make progress. |
1005 | */ |
1006 | activate_page(page); |
1007 | unlock_page(page); |
1008 | down_read(&mm->mmap_sem); |
1009 | lock_page(page); |
1010 | } |
1011 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
1012 | if (vma->anon_vma && (ret = unuse_vma(vma, entry, page))) |
1013 | break; |
1014 | } |
1015 | up_read(&mm->mmap_sem); |
1016 | return (ret < 0)? ret: 0; |
1017 | } |
1018 | |
1019 | /* |
1020 | * Scan swap_map from current position to next entry still in use. |
1021 | * Recycle to start on reaching the end, returning 0 when empty. |
1022 | */ |
1023 | static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
1024 | unsigned int prev) |
1025 | { |
1026 | unsigned int max = si->max; |
1027 | unsigned int i = prev; |
1028 | unsigned char count; |
1029 | |
1030 | /* |
1031 | * No need for swap_lock here: we're just looking |
1032 | * for whether an entry is in use, not modifying it; false |
1033 | * hits are okay, and sys_swapoff() has already prevented new |
1034 | * allocations from this area (while holding swap_lock). |
1035 | */ |
1036 | for (;;) { |
1037 | if (++i >= max) { |
1038 | if (!prev) { |
1039 | i = 0; |
1040 | break; |
1041 | } |
1042 | /* |
1043 | * No entries in use at top of swap_map, |
1044 | * loop back to start and recheck there. |
1045 | */ |
1046 | max = prev + 1; |
1047 | prev = 0; |
1048 | i = 1; |
1049 | } |
1050 | count = si->swap_map[i]; |
1051 | if (count && swap_count(count) != SWAP_MAP_BAD) |
1052 | break; |
1053 | } |
1054 | return i; |
1055 | } |
1056 | |
1057 | /* |
1058 | * We completely avoid races by reading each swap page in advance, |
1059 | * and then search for the process using it. All the necessary |
1060 | * page table adjustments can then be made atomically. |
1061 | */ |
1062 | static int try_to_unuse(unsigned int type) |
1063 | { |
1064 | struct swap_info_struct *si = swap_info[type]; |
1065 | struct mm_struct *start_mm; |
1066 | unsigned char *swap_map; |
1067 | unsigned char swcount; |
1068 | struct page *page; |
1069 | swp_entry_t entry; |
1070 | unsigned int i = 0; |
1071 | int retval = 0; |
1072 | |
1073 | /* |
1074 | * When searching mms for an entry, a good strategy is to |
1075 | * start at the first mm we freed the previous entry from |
1076 | * (though actually we don't notice whether we or coincidence |
1077 | * freed the entry). Initialize this start_mm with a hold. |
1078 | * |
1079 | * A simpler strategy would be to start at the last mm we |
1080 | * freed the previous entry from; but that would take less |
1081 | * advantage of mmlist ordering, which clusters forked mms |
1082 | * together, child after parent. If we race with dup_mmap(), we |
1083 | * prefer to resolve parent before child, lest we miss entries |
1084 | * duplicated after we scanned child: using last mm would invert |
1085 | * that. |
1086 | */ |
1087 | start_mm = &init_mm; |
1088 | atomic_inc(&init_mm.mm_users); |
1089 | |
1090 | /* |
1091 | * Keep on scanning until all entries have gone. Usually, |
1092 | * one pass through swap_map is enough, but not necessarily: |
1093 | * there are races when an instance of an entry might be missed. |
1094 | */ |
1095 | while ((i = find_next_to_unuse(si, i)) != 0) { |
1096 | if (signal_pending(current)) { |
1097 | retval = -EINTR; |
1098 | break; |
1099 | } |
1100 | |
1101 | /* |
1102 | * Get a page for the entry, using the existing swap |
1103 | * cache page if there is one. Otherwise, get a clean |
1104 | * page and read the swap into it. |
1105 | */ |
1106 | swap_map = &si->swap_map[i]; |
1107 | entry = swp_entry(type, i); |
1108 | page = read_swap_cache_async(entry, |
1109 | GFP_HIGHUSER_MOVABLE, NULL, 0); |
1110 | if (!page) { |
1111 | /* |
1112 | * Either swap_duplicate() failed because entry |
1113 | * has been freed independently, and will not be |
1114 | * reused since sys_swapoff() already disabled |
1115 | * allocation from here, or alloc_page() failed. |
1116 | */ |
1117 | if (!*swap_map) |
1118 | continue; |
1119 | retval = -ENOMEM; |
1120 | break; |
1121 | } |
1122 | |
1123 | /* |
1124 | * Don't hold on to start_mm if it looks like exiting. |
1125 | */ |
1126 | if (atomic_read(&start_mm->mm_users) == 1) { |
1127 | mmput(start_mm); |
1128 | start_mm = &init_mm; |
1129 | atomic_inc(&init_mm.mm_users); |
1130 | } |
1131 | |
1132 | /* |
1133 | * Wait for and lock page. When do_swap_page races with |
1134 | * try_to_unuse, do_swap_page can handle the fault much |
1135 | * faster than try_to_unuse can locate the entry. This |
1136 | * apparently redundant "wait_on_page_locked" lets try_to_unuse |
1137 | * defer to do_swap_page in such a case - in some tests, |
1138 | * do_swap_page and try_to_unuse repeatedly compete. |
1139 | */ |
1140 | wait_on_page_locked(page); |
1141 | wait_on_page_writeback(page); |
1142 | lock_page(page); |
1143 | wait_on_page_writeback(page); |
1144 | |
1145 | /* |
1146 | * Remove all references to entry. |
1147 | */ |
1148 | swcount = *swap_map; |
1149 | if (swap_count(swcount) == SWAP_MAP_SHMEM) { |
1150 | retval = shmem_unuse(entry, page); |
1151 | /* page has already been unlocked and released */ |
1152 | if (retval < 0) |
1153 | break; |
1154 | continue; |
1155 | } |
1156 | if (swap_count(swcount) && start_mm != &init_mm) |
1157 | retval = unuse_mm(start_mm, entry, page); |
1158 | |
1159 | if (swap_count(*swap_map)) { |
1160 | int set_start_mm = (*swap_map >= swcount); |
1161 | struct list_head *p = &start_mm->mmlist; |
1162 | struct mm_struct *new_start_mm = start_mm; |
1163 | struct mm_struct *prev_mm = start_mm; |
1164 | struct mm_struct *mm; |
1165 | |
1166 | atomic_inc(&new_start_mm->mm_users); |
1167 | atomic_inc(&prev_mm->mm_users); |
1168 | spin_lock(&mmlist_lock); |
1169 | while (swap_count(*swap_map) && !retval && |
1170 | (p = p->next) != &start_mm->mmlist) { |
1171 | mm = list_entry(p, struct mm_struct, mmlist); |
1172 | if (!atomic_inc_not_zero(&mm->mm_users)) |
1173 | continue; |
1174 | spin_unlock(&mmlist_lock); |
1175 | mmput(prev_mm); |
1176 | prev_mm = mm; |
1177 | |
1178 | cond_resched(); |
1179 | |
1180 | swcount = *swap_map; |
1181 | if (!swap_count(swcount)) /* any usage ? */ |
1182 | ; |
1183 | else if (mm == &init_mm) |
1184 | set_start_mm = 1; |
1185 | else |
1186 | retval = unuse_mm(mm, entry, page); |
1187 | |
1188 | if (set_start_mm && *swap_map < swcount) { |
1189 | mmput(new_start_mm); |
1190 | atomic_inc(&mm->mm_users); |
1191 | new_start_mm = mm; |
1192 | set_start_mm = 0; |
1193 | } |
1194 | spin_lock(&mmlist_lock); |
1195 | } |
1196 | spin_unlock(&mmlist_lock); |
1197 | mmput(prev_mm); |
1198 | mmput(start_mm); |
1199 | start_mm = new_start_mm; |
1200 | } |
1201 | if (retval) { |
1202 | unlock_page(page); |
1203 | page_cache_release(page); |
1204 | break; |
1205 | } |
1206 | |
1207 | /* |
1208 | * If a reference remains (rare), we would like to leave |
1209 | * the page in the swap cache; but try_to_unmap could |
1210 | * then re-duplicate the entry once we drop page lock, |
1211 | * so we might loop indefinitely; also, that page could |
1212 | * not be swapped out to other storage meanwhile. So: |
1213 | * delete from cache even if there's another reference, |
1214 | * after ensuring that the data has been saved to disk - |
1215 | * since if the reference remains (rarer), it will be |
1216 | * read from disk into another page. Splitting into two |
1217 | * pages would be incorrect if swap supported "shared |
1218 | * private" pages, but they are handled by tmpfs files. |
1219 | * |
1220 | * Given how unuse_vma() targets one particular offset |
1221 | * in an anon_vma, once the anon_vma has been determined, |
1222 | * this splitting happens to be just what is needed to |
1223 | * handle where KSM pages have been swapped out: re-reading |
1224 | * is unnecessarily slow, but we can fix that later on. |
1225 | */ |
1226 | if (swap_count(*swap_map) && |
1227 | PageDirty(page) && PageSwapCache(page)) { |
1228 | struct writeback_control wbc = { |
1229 | .sync_mode = WB_SYNC_NONE, |
1230 | }; |
1231 | |
1232 | swap_writepage(page, &wbc); |
1233 | lock_page(page); |
1234 | wait_on_page_writeback(page); |
1235 | } |
1236 | |
1237 | /* |
1238 | * It is conceivable that a racing task removed this page from |
1239 | * swap cache just before we acquired the page lock at the top, |
1240 | * or while we dropped it in unuse_mm(). The page might even |
1241 | * be back in swap cache on another swap area: that we must not |
1242 | * delete, since it may not have been written out to swap yet. |
1243 | */ |
1244 | if (PageSwapCache(page) && |
1245 | likely(page_private(page) == entry.val)) |
1246 | delete_from_swap_cache(page); |
1247 | |
1248 | /* |
1249 | * So we could skip searching mms once swap count went |
1250 | * to 1, we did not mark any present ptes as dirty: must |
1251 | * mark page dirty so shrink_page_list will preserve it. |
1252 | */ |
1253 | SetPageDirty(page); |
1254 | unlock_page(page); |
1255 | page_cache_release(page); |
1256 | |
1257 | /* |
1258 | * Make sure that we aren't completely killing |
1259 | * interactive performance. |
1260 | */ |
1261 | cond_resched(); |
1262 | } |
1263 | |
1264 | mmput(start_mm); |
1265 | return retval; |
1266 | } |
1267 | |
1268 | /* |
1269 | * After a successful try_to_unuse, if no swap is now in use, we know |
1270 | * we can empty the mmlist. swap_lock must be held on entry and exit. |
1271 | * Note that mmlist_lock nests inside swap_lock, and an mm must be |
1272 | * added to the mmlist just after page_duplicate - before would be racy. |
1273 | */ |
1274 | static void drain_mmlist(void) |
1275 | { |
1276 | struct list_head *p, *next; |
1277 | unsigned int type; |
1278 | |
1279 | for (type = 0; type < nr_swapfiles; type++) |
1280 | if (swap_info[type]->inuse_pages) |
1281 | return; |
1282 | spin_lock(&mmlist_lock); |
1283 | list_for_each_safe(p, next, &init_mm.mmlist) |
1284 | list_del_init(p); |
1285 | spin_unlock(&mmlist_lock); |
1286 | } |
1287 | |
1288 | /* |
1289 | * Use this swapdev's extent info to locate the (PAGE_SIZE) block which |
1290 | * corresponds to page offset for the specified swap entry. |
1291 | * Note that the type of this function is sector_t, but it returns page offset |
1292 | * into the bdev, not sector offset. |
1293 | */ |
1294 | static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev) |
1295 | { |
1296 | struct swap_info_struct *sis; |
1297 | struct swap_extent *start_se; |
1298 | struct swap_extent *se; |
1299 | pgoff_t offset; |
1300 | |
1301 | sis = swap_info[swp_type(entry)]; |
1302 | *bdev = sis->bdev; |
1303 | |
1304 | offset = swp_offset(entry); |
1305 | start_se = sis->curr_swap_extent; |
1306 | se = start_se; |
1307 | |
1308 | for ( ; ; ) { |
1309 | struct list_head *lh; |
1310 | |
1311 | if (se->start_page <= offset && |
1312 | offset < (se->start_page + se->nr_pages)) { |
1313 | return se->start_block + (offset - se->start_page); |
1314 | } |
1315 | lh = se->list.next; |
1316 | se = list_entry(lh, struct swap_extent, list); |
1317 | sis->curr_swap_extent = se; |
1318 | BUG_ON(se == start_se); /* It *must* be present */ |
1319 | } |
1320 | } |
1321 | |
1322 | /* |
1323 | * Returns the page offset into bdev for the specified page's swap entry. |
1324 | */ |
1325 | sector_t map_swap_page(struct page *page, struct block_device **bdev) |
1326 | { |
1327 | swp_entry_t entry; |
1328 | entry.val = page_private(page); |
1329 | return map_swap_entry(entry, bdev); |
1330 | } |
1331 | |
1332 | /* |
1333 | * Free all of a swapdev's extent information |
1334 | */ |
1335 | static void destroy_swap_extents(struct swap_info_struct *sis) |
1336 | { |
1337 | while (!list_empty(&sis->first_swap_extent.list)) { |
1338 | struct swap_extent *se; |
1339 | |
1340 | se = list_entry(sis->first_swap_extent.list.next, |
1341 | struct swap_extent, list); |
1342 | list_del(&se->list); |
1343 | kfree(se); |
1344 | } |
1345 | } |
1346 | |
1347 | /* |
1348 | * Add a block range (and the corresponding page range) into this swapdev's |
1349 | * extent list. The extent list is kept sorted in page order. |
1350 | * |
1351 | * This function rather assumes that it is called in ascending page order. |
1352 | */ |
1353 | static int |
1354 | add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, |
1355 | unsigned long nr_pages, sector_t start_block) |
1356 | { |
1357 | struct swap_extent *se; |
1358 | struct swap_extent *new_se; |
1359 | struct list_head *lh; |
1360 | |
1361 | if (start_page == 0) { |
1362 | se = &sis->first_swap_extent; |
1363 | sis->curr_swap_extent = se; |
1364 | se->start_page = 0; |
1365 | se->nr_pages = nr_pages; |
1366 | se->start_block = start_block; |
1367 | return 1; |
1368 | } else { |
1369 | lh = sis->first_swap_extent.list.prev; /* Highest extent */ |
1370 | se = list_entry(lh, struct swap_extent, list); |
1371 | BUG_ON(se->start_page + se->nr_pages != start_page); |
1372 | if (se->start_block + se->nr_pages == start_block) { |
1373 | /* Merge it */ |
1374 | se->nr_pages += nr_pages; |
1375 | return 0; |
1376 | } |
1377 | } |
1378 | |
1379 | /* |
1380 | * No merge. Insert a new extent, preserving ordering. |
1381 | */ |
1382 | new_se = kmalloc(sizeof(*se), GFP_KERNEL); |
1383 | if (new_se == NULL) |
1384 | return -ENOMEM; |
1385 | new_se->start_page = start_page; |
1386 | new_se->nr_pages = nr_pages; |
1387 | new_se->start_block = start_block; |
1388 | |
1389 | list_add_tail(&new_se->list, &sis->first_swap_extent.list); |
1390 | return 1; |
1391 | } |
1392 | |
1393 | /* |
1394 | * A `swap extent' is a simple thing which maps a contiguous range of pages |
1395 | * onto a contiguous range of disk blocks. An ordered list of swap extents |
1396 | * is built at swapon time and is then used at swap_writepage/swap_readpage |
1397 | * time for locating where on disk a page belongs. |
1398 | * |
1399 | * If the swapfile is an S_ISBLK block device, a single extent is installed. |
1400 | * This is done so that the main operating code can treat S_ISBLK and S_ISREG |
1401 | * swap files identically. |
1402 | * |
1403 | * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap |
1404 | * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK |
1405 | * swapfiles are handled *identically* after swapon time. |
1406 | * |
1407 | * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks |
1408 | * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If |
1409 | * some stray blocks are found which do not fall within the PAGE_SIZE alignment |
1410 | * requirements, they are simply tossed out - we will never use those blocks |
1411 | * for swapping. |
1412 | * |
1413 | * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This |
1414 | * prevents root from shooting her foot off by ftruncating an in-use swapfile, |
1415 | * which will scribble on the fs. |
1416 | * |
1417 | * The amount of disk space which a single swap extent represents varies. |
1418 | * Typically it is in the 1-4 megabyte range. So we can have hundreds of |
1419 | * extents in the list. To avoid much list walking, we cache the previous |
1420 | * search location in `curr_swap_extent', and start new searches from there. |
1421 | * This is extremely effective. The average number of iterations in |
1422 | * map_swap_page() has been measured at about 0.3 per page. - akpm. |
1423 | */ |
1424 | static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
1425 | { |
1426 | struct inode *inode; |
1427 | unsigned blocks_per_page; |
1428 | unsigned long page_no; |
1429 | unsigned blkbits; |
1430 | sector_t probe_block; |
1431 | sector_t last_block; |
1432 | sector_t lowest_block = -1; |
1433 | sector_t highest_block = 0; |
1434 | int nr_extents = 0; |
1435 | int ret; |
1436 | |
1437 | inode = sis->swap_file->f_mapping->host; |
1438 | if (S_ISBLK(inode->i_mode)) { |
1439 | ret = add_swap_extent(sis, 0, sis->max, 0); |
1440 | *span = sis->pages; |
1441 | goto out; |
1442 | } |
1443 | |
1444 | blkbits = inode->i_blkbits; |
1445 | blocks_per_page = PAGE_SIZE >> blkbits; |
1446 | |
1447 | /* |
1448 | * Map all the blocks into the extent list. This code doesn't try |
1449 | * to be very smart. |
1450 | */ |
1451 | probe_block = 0; |
1452 | page_no = 0; |
1453 | last_block = i_size_read(inode) >> blkbits; |
1454 | while ((probe_block + blocks_per_page) <= last_block && |
1455 | page_no < sis->max) { |
1456 | unsigned block_in_page; |
1457 | sector_t first_block; |
1458 | |
1459 | first_block = bmap(inode, probe_block); |
1460 | if (first_block == 0) |
1461 | goto bad_bmap; |
1462 | |
1463 | /* |
1464 | * It must be PAGE_SIZE aligned on-disk |
1465 | */ |
1466 | if (first_block & (blocks_per_page - 1)) { |
1467 | probe_block++; |
1468 | goto reprobe; |
1469 | } |
1470 | |
1471 | for (block_in_page = 1; block_in_page < blocks_per_page; |
1472 | block_in_page++) { |
1473 | sector_t block; |
1474 | |
1475 | block = bmap(inode, probe_block + block_in_page); |
1476 | if (block == 0) |
1477 | goto bad_bmap; |
1478 | if (block != first_block + block_in_page) { |
1479 | /* Discontiguity */ |
1480 | probe_block++; |
1481 | goto reprobe; |
1482 | } |
1483 | } |
1484 | |
1485 | first_block >>= (PAGE_SHIFT - blkbits); |
1486 | if (page_no) { /* exclude the header page */ |
1487 | if (first_block < lowest_block) |
1488 | lowest_block = first_block; |
1489 | if (first_block > highest_block) |
1490 | highest_block = first_block; |
1491 | } |
1492 | |
1493 | /* |
1494 | * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks |
1495 | */ |
1496 | ret = add_swap_extent(sis, page_no, 1, first_block); |
1497 | if (ret < 0) |
1498 | goto out; |
1499 | nr_extents += ret; |
1500 | page_no++; |
1501 | probe_block += blocks_per_page; |
1502 | reprobe: |
1503 | continue; |
1504 | } |
1505 | ret = nr_extents; |
1506 | *span = 1 + highest_block - lowest_block; |
1507 | if (page_no == 0) |
1508 | page_no = 1; /* force Empty message */ |
1509 | sis->max = page_no; |
1510 | sis->pages = page_no - 1; |
1511 | sis->highest_bit = page_no - 1; |
1512 | out: |
1513 | return ret; |
1514 | bad_bmap: |
1515 | printk(KERN_ERR "swapon: swapfile has holes\n"); |
1516 | ret = -EINVAL; |
1517 | goto out; |
1518 | } |
1519 | |
1520 | static void enable_swap_info(struct swap_info_struct *p, int prio, |
1521 | unsigned char *swap_map) |
1522 | { |
1523 | int i, prev; |
1524 | |
1525 | spin_lock(&swap_lock); |
1526 | if (prio >= 0) |
1527 | p->prio = prio; |
1528 | else |
1529 | p->prio = --least_priority; |
1530 | p->swap_map = swap_map; |
1531 | p->flags |= SWP_WRITEOK; |
1532 | nr_swap_pages += p->pages; |
1533 | total_swap_pages += p->pages; |
1534 | |
1535 | /* insert swap space into swap_list: */ |
1536 | prev = -1; |
1537 | for (i = swap_list.head; i >= 0; i = swap_info[i]->next) { |
1538 | if (p->prio >= swap_info[i]->prio) |
1539 | break; |
1540 | prev = i; |
1541 | } |
1542 | p->next = i; |
1543 | if (prev < 0) |
1544 | swap_list.head = swap_list.next = p->type; |
1545 | else |
1546 | swap_info[prev]->next = p->type; |
1547 | spin_unlock(&swap_lock); |
1548 | } |
1549 | |
1550 | SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) |
1551 | { |
1552 | struct swap_info_struct *p = NULL; |
1553 | unsigned char *swap_map; |
1554 | struct file *swap_file, *victim; |
1555 | struct address_space *mapping; |
1556 | struct inode *inode; |
1557 | char *pathname; |
1558 | int i, type, prev; |
1559 | int err; |
1560 | |
1561 | if (!capable(CAP_SYS_ADMIN)) |
1562 | return -EPERM; |
1563 | |
1564 | pathname = getname(specialfile); |
1565 | err = PTR_ERR(pathname); |
1566 | if (IS_ERR(pathname)) |
1567 | goto out; |
1568 | |
1569 | victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0); |
1570 | putname(pathname); |
1571 | err = PTR_ERR(victim); |
1572 | if (IS_ERR(victim)) |
1573 | goto out; |
1574 | |
1575 | mapping = victim->f_mapping; |
1576 | prev = -1; |
1577 | spin_lock(&swap_lock); |
1578 | for (type = swap_list.head; type >= 0; type = swap_info[type]->next) { |
1579 | p = swap_info[type]; |
1580 | if (p->flags & SWP_WRITEOK) { |
1581 | if (p->swap_file->f_mapping == mapping) |
1582 | break; |
1583 | } |
1584 | prev = type; |
1585 | } |
1586 | if (type < 0) { |
1587 | err = -EINVAL; |
1588 | spin_unlock(&swap_lock); |
1589 | goto out_dput; |
1590 | } |
1591 | if (!security_vm_enough_memory(p->pages)) |
1592 | vm_unacct_memory(p->pages); |
1593 | else { |
1594 | err = -ENOMEM; |
1595 | spin_unlock(&swap_lock); |
1596 | goto out_dput; |
1597 | } |
1598 | if (prev < 0) |
1599 | swap_list.head = p->next; |
1600 | else |
1601 | swap_info[prev]->next = p->next; |
1602 | if (type == swap_list.next) { |
1603 | /* just pick something that's safe... */ |
1604 | swap_list.next = swap_list.head; |
1605 | } |
1606 | if (p->prio < 0) { |
1607 | for (i = p->next; i >= 0; i = swap_info[i]->next) |
1608 | swap_info[i]->prio = p->prio--; |
1609 | least_priority++; |
1610 | } |
1611 | nr_swap_pages -= p->pages; |
1612 | total_swap_pages -= p->pages; |
1613 | p->flags &= ~SWP_WRITEOK; |
1614 | spin_unlock(&swap_lock); |
1615 | |
1616 | current->flags |= PF_OOM_ORIGIN; |
1617 | err = try_to_unuse(type); |
1618 | current->flags &= ~PF_OOM_ORIGIN; |
1619 | |
1620 | if (err) { |
1621 | /* |
1622 | * reading p->prio and p->swap_map outside the lock is |
1623 | * safe here because only sys_swapon and sys_swapoff |
1624 | * change them, and there can be no other sys_swapon or |
1625 | * sys_swapoff for this swap_info_struct at this point. |
1626 | */ |
1627 | /* re-insert swap space back into swap_list */ |
1628 | enable_swap_info(p, p->prio, p->swap_map); |
1629 | goto out_dput; |
1630 | } |
1631 | |
1632 | destroy_swap_extents(p); |
1633 | if (p->flags & SWP_CONTINUED) |
1634 | free_swap_count_continuations(p); |
1635 | |
1636 | mutex_lock(&swapon_mutex); |
1637 | spin_lock(&swap_lock); |
1638 | drain_mmlist(); |
1639 | |
1640 | /* wait for anyone still in scan_swap_map */ |
1641 | p->highest_bit = 0; /* cuts scans short */ |
1642 | while (p->flags >= SWP_SCANNING) { |
1643 | spin_unlock(&swap_lock); |
1644 | schedule_timeout_uninterruptible(1); |
1645 | spin_lock(&swap_lock); |
1646 | } |
1647 | |
1648 | swap_file = p->swap_file; |
1649 | p->swap_file = NULL; |
1650 | p->max = 0; |
1651 | swap_map = p->swap_map; |
1652 | p->swap_map = NULL; |
1653 | p->flags = 0; |
1654 | spin_unlock(&swap_lock); |
1655 | mutex_unlock(&swapon_mutex); |
1656 | vfree(swap_map); |
1657 | /* Destroy swap account informatin */ |
1658 | swap_cgroup_swapoff(type); |
1659 | |
1660 | inode = mapping->host; |
1661 | if (S_ISBLK(inode->i_mode)) { |
1662 | struct block_device *bdev = I_BDEV(inode); |
1663 | set_blocksize(bdev, p->old_block_size); |
1664 | blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); |
1665 | } else { |
1666 | mutex_lock(&inode->i_mutex); |
1667 | inode->i_flags &= ~S_SWAPFILE; |
1668 | mutex_unlock(&inode->i_mutex); |
1669 | } |
1670 | filp_close(swap_file, NULL); |
1671 | err = 0; |
1672 | atomic_inc(&proc_poll_event); |
1673 | wake_up_interruptible(&proc_poll_wait); |
1674 | |
1675 | out_dput: |
1676 | filp_close(victim, NULL); |
1677 | out: |
1678 | return err; |
1679 | } |
1680 | |
1681 | #ifdef CONFIG_PROC_FS |
1682 | struct proc_swaps { |
1683 | struct seq_file seq; |
1684 | int event; |
1685 | }; |
1686 | |
1687 | static unsigned swaps_poll(struct file *file, poll_table *wait) |
1688 | { |
1689 | struct proc_swaps *s = file->private_data; |
1690 | |
1691 | poll_wait(file, &proc_poll_wait, wait); |
1692 | |
1693 | if (s->event != atomic_read(&proc_poll_event)) { |
1694 | s->event = atomic_read(&proc_poll_event); |
1695 | return POLLIN | POLLRDNORM | POLLERR | POLLPRI; |
1696 | } |
1697 | |
1698 | return POLLIN | POLLRDNORM; |
1699 | } |
1700 | |
1701 | /* iterator */ |
1702 | static void *swap_start(struct seq_file *swap, loff_t *pos) |
1703 | { |
1704 | struct swap_info_struct *si; |
1705 | int type; |
1706 | loff_t l = *pos; |
1707 | |
1708 | mutex_lock(&swapon_mutex); |
1709 | |
1710 | if (!l) |
1711 | return SEQ_START_TOKEN; |
1712 | |
1713 | for (type = 0; type < nr_swapfiles; type++) { |
1714 | smp_rmb(); /* read nr_swapfiles before swap_info[type] */ |
1715 | si = swap_info[type]; |
1716 | if (!(si->flags & SWP_USED) || !si->swap_map) |
1717 | continue; |
1718 | if (!--l) |
1719 | return si; |
1720 | } |
1721 | |
1722 | return NULL; |
1723 | } |
1724 | |
1725 | static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) |
1726 | { |
1727 | struct swap_info_struct *si = v; |
1728 | int type; |
1729 | |
1730 | if (v == SEQ_START_TOKEN) |
1731 | type = 0; |
1732 | else |
1733 | type = si->type + 1; |
1734 | |
1735 | for (; type < nr_swapfiles; type++) { |
1736 | smp_rmb(); /* read nr_swapfiles before swap_info[type] */ |
1737 | si = swap_info[type]; |
1738 | if (!(si->flags & SWP_USED) || !si->swap_map) |
1739 | continue; |
1740 | ++*pos; |
1741 | return si; |
1742 | } |
1743 | |
1744 | return NULL; |
1745 | } |
1746 | |
1747 | static void swap_stop(struct seq_file *swap, void *v) |
1748 | { |
1749 | mutex_unlock(&swapon_mutex); |
1750 | } |
1751 | |
1752 | static int swap_show(struct seq_file *swap, void *v) |
1753 | { |
1754 | struct swap_info_struct *si = v; |
1755 | struct file *file; |
1756 | int len; |
1757 | |
1758 | if (si == SEQ_START_TOKEN) { |
1759 | seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n"); |
1760 | return 0; |
1761 | } |
1762 | |
1763 | file = si->swap_file; |
1764 | len = seq_path(swap, &file->f_path, " \t\n\\"); |
1765 | seq_printf(swap, "%*s%s\t%u\t%u\t%d\n", |
1766 | len < 40 ? 40 - len : 1, " ", |
1767 | S_ISBLK(file->f_path.dentry->d_inode->i_mode) ? |
1768 | "partition" : "file\t", |
1769 | si->pages << (PAGE_SHIFT - 10), |
1770 | si->inuse_pages << (PAGE_SHIFT - 10), |
1771 | si->prio); |
1772 | return 0; |
1773 | } |
1774 | |
1775 | static const struct seq_operations swaps_op = { |
1776 | .start = swap_start, |
1777 | .next = swap_next, |
1778 | .stop = swap_stop, |
1779 | .show = swap_show |
1780 | }; |
1781 | |
1782 | static int swaps_open(struct inode *inode, struct file *file) |
1783 | { |
1784 | struct proc_swaps *s; |
1785 | int ret; |
1786 | |
1787 | s = kmalloc(sizeof(struct proc_swaps), GFP_KERNEL); |
1788 | if (!s) |
1789 | return -ENOMEM; |
1790 | |
1791 | file->private_data = s; |
1792 | |
1793 | ret = seq_open(file, &swaps_op); |
1794 | if (ret) { |
1795 | kfree(s); |
1796 | return ret; |
1797 | } |
1798 | |
1799 | s->seq.private = s; |
1800 | s->event = atomic_read(&proc_poll_event); |
1801 | return ret; |
1802 | } |
1803 | |
1804 | static const struct file_operations proc_swaps_operations = { |
1805 | .open = swaps_open, |
1806 | .read = seq_read, |
1807 | .llseek = seq_lseek, |
1808 | .release = seq_release, |
1809 | .poll = swaps_poll, |
1810 | }; |
1811 | |
1812 | static int __init procswaps_init(void) |
1813 | { |
1814 | proc_create("swaps", 0, NULL, &proc_swaps_operations); |
1815 | return 0; |
1816 | } |
1817 | __initcall(procswaps_init); |
1818 | #endif /* CONFIG_PROC_FS */ |
1819 | |
1820 | #ifdef MAX_SWAPFILES_CHECK |
1821 | static int __init max_swapfiles_check(void) |
1822 | { |
1823 | MAX_SWAPFILES_CHECK(); |
1824 | return 0; |
1825 | } |
1826 | late_initcall(max_swapfiles_check); |
1827 | #endif |
1828 | |
1829 | static struct swap_info_struct *alloc_swap_info(void) |
1830 | { |
1831 | struct swap_info_struct *p; |
1832 | unsigned int type; |
1833 | |
1834 | p = kzalloc(sizeof(*p), GFP_KERNEL); |
1835 | if (!p) |
1836 | return ERR_PTR(-ENOMEM); |
1837 | |
1838 | spin_lock(&swap_lock); |
1839 | for (type = 0; type < nr_swapfiles; type++) { |
1840 | if (!(swap_info[type]->flags & SWP_USED)) |
1841 | break; |
1842 | } |
1843 | if (type >= MAX_SWAPFILES) { |
1844 | spin_unlock(&swap_lock); |
1845 | kfree(p); |
1846 | return ERR_PTR(-EPERM); |
1847 | } |
1848 | if (type >= nr_swapfiles) { |
1849 | p->type = type; |
1850 | swap_info[type] = p; |
1851 | /* |
1852 | * Write swap_info[type] before nr_swapfiles, in case a |
1853 | * racing procfs swap_start() or swap_next() is reading them. |
1854 | * (We never shrink nr_swapfiles, we never free this entry.) |
1855 | */ |
1856 | smp_wmb(); |
1857 | nr_swapfiles++; |
1858 | } else { |
1859 | kfree(p); |
1860 | p = swap_info[type]; |
1861 | /* |
1862 | * Do not memset this entry: a racing procfs swap_next() |
1863 | * would be relying on p->type to remain valid. |
1864 | */ |
1865 | } |
1866 | INIT_LIST_HEAD(&p->first_swap_extent.list); |
1867 | p->flags = SWP_USED; |
1868 | p->next = -1; |
1869 | spin_unlock(&swap_lock); |
1870 | |
1871 | return p; |
1872 | } |
1873 | |
1874 | static int claim_swapfile(struct swap_info_struct *p, struct inode *inode) |
1875 | { |
1876 | int error; |
1877 | |
1878 | if (S_ISBLK(inode->i_mode)) { |
1879 | p->bdev = bdgrab(I_BDEV(inode)); |
1880 | error = blkdev_get(p->bdev, |
1881 | FMODE_READ | FMODE_WRITE | FMODE_EXCL, |
1882 | sys_swapon); |
1883 | if (error < 0) { |
1884 | p->bdev = NULL; |
1885 | return -EINVAL; |
1886 | } |
1887 | p->old_block_size = block_size(p->bdev); |
1888 | error = set_blocksize(p->bdev, PAGE_SIZE); |
1889 | if (error < 0) |
1890 | return error; |
1891 | p->flags |= SWP_BLKDEV; |
1892 | } else if (S_ISREG(inode->i_mode)) { |
1893 | p->bdev = inode->i_sb->s_bdev; |
1894 | mutex_lock(&inode->i_mutex); |
1895 | if (IS_SWAPFILE(inode)) |
1896 | return -EBUSY; |
1897 | } else |
1898 | return -EINVAL; |
1899 | |
1900 | return 0; |
1901 | } |
1902 | |
1903 | static unsigned long read_swap_header(struct swap_info_struct *p, |
1904 | union swap_header *swap_header, |
1905 | struct inode *inode) |
1906 | { |
1907 | int i; |
1908 | unsigned long maxpages; |
1909 | unsigned long swapfilepages; |
1910 | |
1911 | if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) { |
1912 | printk(KERN_ERR "Unable to find swap-space signature\n"); |
1913 | return 0; |
1914 | } |
1915 | |
1916 | /* swap partition endianess hack... */ |
1917 | if (swab32(swap_header->info.version) == 1) { |
1918 | swab32s(&swap_header->info.version); |
1919 | swab32s(&swap_header->info.last_page); |
1920 | swab32s(&swap_header->info.nr_badpages); |
1921 | for (i = 0; i < swap_header->info.nr_badpages; i++) |
1922 | swab32s(&swap_header->info.badpages[i]); |
1923 | } |
1924 | /* Check the swap header's sub-version */ |
1925 | if (swap_header->info.version != 1) { |
1926 | printk(KERN_WARNING |
1927 | "Unable to handle swap header version %d\n", |
1928 | swap_header->info.version); |
1929 | return 0; |
1930 | } |
1931 | |
1932 | p->lowest_bit = 1; |
1933 | p->cluster_next = 1; |
1934 | p->cluster_nr = 0; |
1935 | |
1936 | /* |
1937 | * Find out how many pages are allowed for a single swap |
1938 | * device. There are two limiting factors: 1) the number of |
1939 | * bits for the swap offset in the swp_entry_t type and |
1940 | * 2) the number of bits in the a swap pte as defined by |
1941 | * the different architectures. In order to find the |
1942 | * largest possible bit mask a swap entry with swap type 0 |
1943 | * and swap offset ~0UL is created, encoded to a swap pte, |
1944 | * decoded to a swp_entry_t again and finally the swap |
1945 | * offset is extracted. This will mask all the bits from |
1946 | * the initial ~0UL mask that can't be encoded in either |
1947 | * the swp_entry_t or the architecture definition of a |
1948 | * swap pte. |
1949 | */ |
1950 | maxpages = swp_offset(pte_to_swp_entry( |
1951 | swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1; |
1952 | if (maxpages > swap_header->info.last_page) { |
1953 | maxpages = swap_header->info.last_page + 1; |
1954 | /* p->max is an unsigned int: don't overflow it */ |
1955 | if ((unsigned int)maxpages == 0) |
1956 | maxpages = UINT_MAX; |
1957 | } |
1958 | p->highest_bit = maxpages - 1; |
1959 | |
1960 | if (!maxpages) |
1961 | return 0; |
1962 | swapfilepages = i_size_read(inode) >> PAGE_SHIFT; |
1963 | if (swapfilepages && maxpages > swapfilepages) { |
1964 | printk(KERN_WARNING |
1965 | "Swap area shorter than signature indicates\n"); |
1966 | return 0; |
1967 | } |
1968 | if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) |
1969 | return 0; |
1970 | if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
1971 | return 0; |
1972 | |
1973 | return maxpages; |
1974 | } |
1975 | |
1976 | static int setup_swap_map_and_extents(struct swap_info_struct *p, |
1977 | union swap_header *swap_header, |
1978 | unsigned char *swap_map, |
1979 | unsigned long maxpages, |
1980 | sector_t *span) |
1981 | { |
1982 | int i; |
1983 | unsigned int nr_good_pages; |
1984 | int nr_extents; |
1985 | |
1986 | nr_good_pages = maxpages - 1; /* omit header page */ |
1987 | |
1988 | for (i = 0; i < swap_header->info.nr_badpages; i++) { |
1989 | unsigned int page_nr = swap_header->info.badpages[i]; |
1990 | if (page_nr == 0 || page_nr > swap_header->info.last_page) |
1991 | return -EINVAL; |
1992 | if (page_nr < maxpages) { |
1993 | swap_map[page_nr] = SWAP_MAP_BAD; |
1994 | nr_good_pages--; |
1995 | } |
1996 | } |
1997 | |
1998 | if (nr_good_pages) { |
1999 | swap_map[0] = SWAP_MAP_BAD; |
2000 | p->max = maxpages; |
2001 | p->pages = nr_good_pages; |
2002 | nr_extents = setup_swap_extents(p, span); |
2003 | if (nr_extents < 0) |
2004 | return nr_extents; |
2005 | nr_good_pages = p->pages; |
2006 | } |
2007 | if (!nr_good_pages) { |
2008 | printk(KERN_WARNING "Empty swap-file\n"); |
2009 | return -EINVAL; |
2010 | } |
2011 | |
2012 | return nr_extents; |
2013 | } |
2014 | |
2015 | SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) |
2016 | { |
2017 | struct swap_info_struct *p; |
2018 | char *name; |
2019 | struct file *swap_file = NULL; |
2020 | struct address_space *mapping; |
2021 | int i; |
2022 | int prio; |
2023 | int error; |
2024 | union swap_header *swap_header; |
2025 | int nr_extents; |
2026 | sector_t span; |
2027 | unsigned long maxpages; |
2028 | unsigned char *swap_map = NULL; |
2029 | struct page *page = NULL; |
2030 | struct inode *inode = NULL; |
2031 | |
2032 | if (!capable(CAP_SYS_ADMIN)) |
2033 | return -EPERM; |
2034 | |
2035 | p = alloc_swap_info(); |
2036 | if (IS_ERR(p)) |
2037 | return PTR_ERR(p); |
2038 | |
2039 | name = getname(specialfile); |
2040 | if (IS_ERR(name)) { |
2041 | error = PTR_ERR(name); |
2042 | name = NULL; |
2043 | goto bad_swap; |
2044 | } |
2045 | swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0); |
2046 | if (IS_ERR(swap_file)) { |
2047 | error = PTR_ERR(swap_file); |
2048 | swap_file = NULL; |
2049 | goto bad_swap; |
2050 | } |
2051 | |
2052 | p->swap_file = swap_file; |
2053 | mapping = swap_file->f_mapping; |
2054 | |
2055 | for (i = 0; i < nr_swapfiles; i++) { |
2056 | struct swap_info_struct *q = swap_info[i]; |
2057 | |
2058 | if (q == p || !q->swap_file) |
2059 | continue; |
2060 | if (mapping == q->swap_file->f_mapping) { |
2061 | error = -EBUSY; |
2062 | goto bad_swap; |
2063 | } |
2064 | } |
2065 | |
2066 | inode = mapping->host; |
2067 | /* If S_ISREG(inode->i_mode) will do mutex_lock(&inode->i_mutex); */ |
2068 | error = claim_swapfile(p, inode); |
2069 | if (unlikely(error)) |
2070 | goto bad_swap; |
2071 | |
2072 | /* |
2073 | * Read the swap header. |
2074 | */ |
2075 | if (!mapping->a_ops->readpage) { |
2076 | error = -EINVAL; |
2077 | goto bad_swap; |
2078 | } |
2079 | page = read_mapping_page(mapping, 0, swap_file); |
2080 | if (IS_ERR(page)) { |
2081 | error = PTR_ERR(page); |
2082 | goto bad_swap; |
2083 | } |
2084 | swap_header = kmap(page); |
2085 | |
2086 | maxpages = read_swap_header(p, swap_header, inode); |
2087 | if (unlikely(!maxpages)) { |
2088 | error = -EINVAL; |
2089 | goto bad_swap; |
2090 | } |
2091 | |
2092 | /* OK, set up the swap map and apply the bad block list */ |
2093 | swap_map = vzalloc(maxpages); |
2094 | if (!swap_map) { |
2095 | error = -ENOMEM; |
2096 | goto bad_swap; |
2097 | } |
2098 | |
2099 | error = swap_cgroup_swapon(p->type, maxpages); |
2100 | if (error) |
2101 | goto bad_swap; |
2102 | |
2103 | nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map, |
2104 | maxpages, &span); |
2105 | if (unlikely(nr_extents < 0)) { |
2106 | error = nr_extents; |
2107 | goto bad_swap; |
2108 | } |
2109 | |
2110 | if (p->bdev) { |
2111 | if (blk_queue_nonrot(bdev_get_queue(p->bdev))) { |
2112 | p->flags |= SWP_SOLIDSTATE; |
2113 | p->cluster_next = 1 + (random32() % p->highest_bit); |
2114 | } |
2115 | if (discard_swap(p) == 0 && (swap_flags & SWAP_FLAG_DISCARD)) |
2116 | p->flags |= SWP_DISCARDABLE; |
2117 | } |
2118 | |
2119 | mutex_lock(&swapon_mutex); |
2120 | prio = -1; |
2121 | if (swap_flags & SWAP_FLAG_PREFER) |
2122 | prio = |
2123 | (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; |
2124 | enable_swap_info(p, prio, swap_map); |
2125 | |
2126 | printk(KERN_INFO "Adding %uk swap on %s. " |
2127 | "Priority:%d extents:%d across:%lluk %s%s\n", |
2128 | p->pages<<(PAGE_SHIFT-10), name, p->prio, |
2129 | nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), |
2130 | (p->flags & SWP_SOLIDSTATE) ? "SS" : "", |
2131 | (p->flags & SWP_DISCARDABLE) ? "D" : ""); |
2132 | |
2133 | mutex_unlock(&swapon_mutex); |
2134 | atomic_inc(&proc_poll_event); |
2135 | wake_up_interruptible(&proc_poll_wait); |
2136 | |
2137 | if (S_ISREG(inode->i_mode)) |
2138 | inode->i_flags |= S_SWAPFILE; |
2139 | error = 0; |
2140 | goto out; |
2141 | bad_swap: |
2142 | if (inode && S_ISBLK(inode->i_mode) && p->bdev) { |
2143 | set_blocksize(p->bdev, p->old_block_size); |
2144 | blkdev_put(p->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); |
2145 | } |
2146 | destroy_swap_extents(p); |
2147 | swap_cgroup_swapoff(p->type); |
2148 | spin_lock(&swap_lock); |
2149 | p->swap_file = NULL; |
2150 | p->flags = 0; |
2151 | spin_unlock(&swap_lock); |
2152 | vfree(swap_map); |
2153 | if (swap_file) { |
2154 | if (inode && S_ISREG(inode->i_mode)) { |
2155 | mutex_unlock(&inode->i_mutex); |
2156 | inode = NULL; |
2157 | } |
2158 | filp_close(swap_file, NULL); |
2159 | } |
2160 | out: |
2161 | if (page && !IS_ERR(page)) { |
2162 | kunmap(page); |
2163 | page_cache_release(page); |
2164 | } |
2165 | if (name) |
2166 | putname(name); |
2167 | if (inode && S_ISREG(inode->i_mode)) |
2168 | mutex_unlock(&inode->i_mutex); |
2169 | return error; |
2170 | } |
2171 | |
2172 | void si_swapinfo(struct sysinfo *val) |
2173 | { |
2174 | unsigned int type; |
2175 | unsigned long nr_to_be_unused = 0; |
2176 | |
2177 | spin_lock(&swap_lock); |
2178 | for (type = 0; type < nr_swapfiles; type++) { |
2179 | struct swap_info_struct *si = swap_info[type]; |
2180 | |
2181 | if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK)) |
2182 | nr_to_be_unused += si->inuse_pages; |
2183 | } |
2184 | val->freeswap = nr_swap_pages + nr_to_be_unused; |
2185 | val->totalswap = total_swap_pages + nr_to_be_unused; |
2186 | spin_unlock(&swap_lock); |
2187 | } |
2188 | |
2189 | /* |
2190 | * Verify that a swap entry is valid and increment its swap map count. |
2191 | * |
2192 | * Returns error code in following case. |
2193 | * - success -> 0 |
2194 | * - swp_entry is invalid -> EINVAL |
2195 | * - swp_entry is migration entry -> EINVAL |
2196 | * - swap-cache reference is requested but there is already one. -> EEXIST |
2197 | * - swap-cache reference is requested but the entry is not used. -> ENOENT |
2198 | * - swap-mapped reference requested but needs continued swap count. -> ENOMEM |
2199 | */ |
2200 | static int __swap_duplicate(swp_entry_t entry, unsigned char usage) |
2201 | { |
2202 | struct swap_info_struct *p; |
2203 | unsigned long offset, type; |
2204 | unsigned char count; |
2205 | unsigned char has_cache; |
2206 | int err = -EINVAL; |
2207 | |
2208 | if (non_swap_entry(entry)) |
2209 | goto out; |
2210 | |
2211 | type = swp_type(entry); |
2212 | if (type >= nr_swapfiles) |
2213 | goto bad_file; |
2214 | p = swap_info[type]; |
2215 | offset = swp_offset(entry); |
2216 | |
2217 | spin_lock(&swap_lock); |
2218 | if (unlikely(offset >= p->max)) |
2219 | goto unlock_out; |
2220 | |
2221 | count = p->swap_map[offset]; |
2222 | has_cache = count & SWAP_HAS_CACHE; |
2223 | count &= ~SWAP_HAS_CACHE; |
2224 | err = 0; |
2225 | |
2226 | if (usage == SWAP_HAS_CACHE) { |
2227 | |
2228 | /* set SWAP_HAS_CACHE if there is no cache and entry is used */ |
2229 | if (!has_cache && count) |
2230 | has_cache = SWAP_HAS_CACHE; |
2231 | else if (has_cache) /* someone else added cache */ |
2232 | err = -EEXIST; |
2233 | else /* no users remaining */ |
2234 | err = -ENOENT; |
2235 | |
2236 | } else if (count || has_cache) { |
2237 | |
2238 | if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX) |
2239 | count += usage; |
2240 | else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) |
2241 | err = -EINVAL; |
2242 | else if (swap_count_continued(p, offset, count)) |
2243 | count = COUNT_CONTINUED; |
2244 | else |
2245 | err = -ENOMEM; |
2246 | } else |
2247 | err = -ENOENT; /* unused swap entry */ |
2248 | |
2249 | p->swap_map[offset] = count | has_cache; |
2250 | |
2251 | unlock_out: |
2252 | spin_unlock(&swap_lock); |
2253 | out: |
2254 | return err; |
2255 | |
2256 | bad_file: |
2257 | printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val); |
2258 | goto out; |
2259 | } |
2260 | |
2261 | /* |
2262 | * Help swapoff by noting that swap entry belongs to shmem/tmpfs |
2263 | * (in which case its reference count is never incremented). |
2264 | */ |
2265 | void swap_shmem_alloc(swp_entry_t entry) |
2266 | { |
2267 | __swap_duplicate(entry, SWAP_MAP_SHMEM); |
2268 | } |
2269 | |
2270 | /* |
2271 | * Increase reference count of swap entry by 1. |
2272 | * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required |
2273 | * but could not be atomically allocated. Returns 0, just as if it succeeded, |
2274 | * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which |
2275 | * might occur if a page table entry has got corrupted. |
2276 | */ |
2277 | int swap_duplicate(swp_entry_t entry) |
2278 | { |
2279 | int err = 0; |
2280 | |
2281 | while (!err && __swap_duplicate(entry, 1) == -ENOMEM) |
2282 | err = add_swap_count_continuation(entry, GFP_ATOMIC); |
2283 | return err; |
2284 | } |
2285 | |
2286 | /* |
2287 | * @entry: swap entry for which we allocate swap cache. |
2288 | * |
2289 | * Called when allocating swap cache for existing swap entry, |
2290 | * This can return error codes. Returns 0 at success. |
2291 | * -EBUSY means there is a swap cache. |
2292 | * Note: return code is different from swap_duplicate(). |
2293 | */ |
2294 | int swapcache_prepare(swp_entry_t entry) |
2295 | { |
2296 | return __swap_duplicate(entry, SWAP_HAS_CACHE); |
2297 | } |
2298 | |
2299 | /* |
2300 | * swap_lock prevents swap_map being freed. Don't grab an extra |
2301 | * reference on the swaphandle, it doesn't matter if it becomes unused. |
2302 | */ |
2303 | int valid_swaphandles(swp_entry_t entry, unsigned long *offset) |
2304 | { |
2305 | struct swap_info_struct *si; |
2306 | int our_page_cluster = page_cluster; |
2307 | pgoff_t target, toff; |
2308 | pgoff_t base, end; |
2309 | int nr_pages = 0; |
2310 | |
2311 | if (!our_page_cluster) /* no readahead */ |
2312 | return 0; |
2313 | |
2314 | si = swap_info[swp_type(entry)]; |
2315 | target = swp_offset(entry); |
2316 | base = (target >> our_page_cluster) << our_page_cluster; |
2317 | end = base + (1 << our_page_cluster); |
2318 | if (!base) /* first page is swap header */ |
2319 | base++; |
2320 | |
2321 | spin_lock(&swap_lock); |
2322 | if (end > si->max) /* don't go beyond end of map */ |
2323 | end = si->max; |
2324 | |
2325 | /* Count contiguous allocated slots above our target */ |
2326 | for (toff = target; ++toff < end; nr_pages++) { |
2327 | /* Don't read in free or bad pages */ |
2328 | if (!si->swap_map[toff]) |
2329 | break; |
2330 | if (swap_count(si->swap_map[toff]) == SWAP_MAP_BAD) |
2331 | break; |
2332 | } |
2333 | /* Count contiguous allocated slots below our target */ |
2334 | for (toff = target; --toff >= base; nr_pages++) { |
2335 | /* Don't read in free or bad pages */ |
2336 | if (!si->swap_map[toff]) |
2337 | break; |
2338 | if (swap_count(si->swap_map[toff]) == SWAP_MAP_BAD) |
2339 | break; |
2340 | } |
2341 | spin_unlock(&swap_lock); |
2342 | |
2343 | /* |
2344 | * Indicate starting offset, and return number of pages to get: |
2345 | * if only 1, say 0, since there's then no readahead to be done. |
2346 | */ |
2347 | *offset = ++toff; |
2348 | return nr_pages? ++nr_pages: 0; |
2349 | } |
2350 | |
2351 | /* |
2352 | * add_swap_count_continuation - called when a swap count is duplicated |
2353 | * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's |
2354 | * page of the original vmalloc'ed swap_map, to hold the continuation count |
2355 | * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called |
2356 | * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc. |
2357 | * |
2358 | * These continuation pages are seldom referenced: the common paths all work |
2359 | * on the original swap_map, only referring to a continuation page when the |
2360 | * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX. |
2361 | * |
2362 | * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding |
2363 | * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL) |
2364 | * can be called after dropping locks. |
2365 | */ |
2366 | int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask) |
2367 | { |
2368 | struct swap_info_struct *si; |
2369 | struct page *head; |
2370 | struct page *page; |
2371 | struct page *list_page; |
2372 | pgoff_t offset; |
2373 | unsigned char count; |
2374 | |
2375 | /* |
2376 | * When debugging, it's easier to use __GFP_ZERO here; but it's better |
2377 | * for latency not to zero a page while GFP_ATOMIC and holding locks. |
2378 | */ |
2379 | page = alloc_page(gfp_mask | __GFP_HIGHMEM); |
2380 | |
2381 | si = swap_info_get(entry); |
2382 | if (!si) { |
2383 | /* |
2384 | * An acceptable race has occurred since the failing |
2385 | * __swap_duplicate(): the swap entry has been freed, |
2386 | * perhaps even the whole swap_map cleared for swapoff. |
2387 | */ |
2388 | goto outer; |
2389 | } |
2390 | |
2391 | offset = swp_offset(entry); |
2392 | count = si->swap_map[offset] & ~SWAP_HAS_CACHE; |
2393 | |
2394 | if ((count & ~COUNT_CONTINUED) != SWAP_MAP_MAX) { |
2395 | /* |
2396 | * The higher the swap count, the more likely it is that tasks |
2397 | * will race to add swap count continuation: we need to avoid |
2398 | * over-provisioning. |
2399 | */ |
2400 | goto out; |
2401 | } |
2402 | |
2403 | if (!page) { |
2404 | spin_unlock(&swap_lock); |
2405 | return -ENOMEM; |
2406 | } |
2407 | |
2408 | /* |
2409 | * We are fortunate that although vmalloc_to_page uses pte_offset_map, |
2410 | * no architecture is using highmem pages for kernel pagetables: so it |
2411 | * will not corrupt the GFP_ATOMIC caller's atomic pagetable kmaps. |
2412 | */ |
2413 | head = vmalloc_to_page(si->swap_map + offset); |
2414 | offset &= ~PAGE_MASK; |
2415 | |
2416 | /* |
2417 | * Page allocation does not initialize the page's lru field, |
2418 | * but it does always reset its private field. |
2419 | */ |
2420 | if (!page_private(head)) { |
2421 | BUG_ON(count & COUNT_CONTINUED); |
2422 | INIT_LIST_HEAD(&head->lru); |
2423 | set_page_private(head, SWP_CONTINUED); |
2424 | si->flags |= SWP_CONTINUED; |
2425 | } |
2426 | |
2427 | list_for_each_entry(list_page, &head->lru, lru) { |
2428 | unsigned char *map; |
2429 | |
2430 | /* |
2431 | * If the previous map said no continuation, but we've found |
2432 | * a continuation page, free our allocation and use this one. |
2433 | */ |
2434 | if (!(count & COUNT_CONTINUED)) |
2435 | goto out; |
2436 | |
2437 | map = kmap_atomic(list_page, KM_USER0) + offset; |
2438 | count = *map; |
2439 | kunmap_atomic(map, KM_USER0); |
2440 | |
2441 | /* |
2442 | * If this continuation count now has some space in it, |
2443 | * free our allocation and use this one. |
2444 | */ |
2445 | if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX) |
2446 | goto out; |
2447 | } |
2448 | |
2449 | list_add_tail(&page->lru, &head->lru); |
2450 | page = NULL; /* now it's attached, don't free it */ |
2451 | out: |
2452 | spin_unlock(&swap_lock); |
2453 | outer: |
2454 | if (page) |
2455 | __free_page(page); |
2456 | return 0; |
2457 | } |
2458 | |
2459 | /* |
2460 | * swap_count_continued - when the original swap_map count is incremented |
2461 | * from SWAP_MAP_MAX, check if there is already a continuation page to carry |
2462 | * into, carry if so, or else fail until a new continuation page is allocated; |
2463 | * when the original swap_map count is decremented from 0 with continuation, |
2464 | * borrow from the continuation and report whether it still holds more. |
2465 | * Called while __swap_duplicate() or swap_entry_free() holds swap_lock. |
2466 | */ |
2467 | static bool swap_count_continued(struct swap_info_struct *si, |
2468 | pgoff_t offset, unsigned char count) |
2469 | { |
2470 | struct page *head; |
2471 | struct page *page; |
2472 | unsigned char *map; |
2473 | |
2474 | head = vmalloc_to_page(si->swap_map + offset); |
2475 | if (page_private(head) != SWP_CONTINUED) { |
2476 | BUG_ON(count & COUNT_CONTINUED); |
2477 | return false; /* need to add count continuation */ |
2478 | } |
2479 | |
2480 | offset &= ~PAGE_MASK; |
2481 | page = list_entry(head->lru.next, struct page, lru); |
2482 | map = kmap_atomic(page, KM_USER0) + offset; |
2483 | |
2484 | if (count == SWAP_MAP_MAX) /* initial increment from swap_map */ |
2485 | goto init_map; /* jump over SWAP_CONT_MAX checks */ |
2486 | |
2487 | if (count == (SWAP_MAP_MAX | COUNT_CONTINUED)) { /* incrementing */ |
2488 | /* |
2489 | * Think of how you add 1 to 999 |
2490 | */ |
2491 | while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) { |
2492 | kunmap_atomic(map, KM_USER0); |
2493 | page = list_entry(page->lru.next, struct page, lru); |
2494 | BUG_ON(page == head); |
2495 | map = kmap_atomic(page, KM_USER0) + offset; |
2496 | } |
2497 | if (*map == SWAP_CONT_MAX) { |
2498 | kunmap_atomic(map, KM_USER0); |
2499 | page = list_entry(page->lru.next, struct page, lru); |
2500 | if (page == head) |
2501 | return false; /* add count continuation */ |
2502 | map = kmap_atomic(page, KM_USER0) + offset; |
2503 | init_map: *map = 0; /* we didn't zero the page */ |
2504 | } |
2505 | *map += 1; |
2506 | kunmap_atomic(map, KM_USER0); |
2507 | page = list_entry(page->lru.prev, struct page, lru); |
2508 | while (page != head) { |
2509 | map = kmap_atomic(page, KM_USER0) + offset; |
2510 | *map = COUNT_CONTINUED; |
2511 | kunmap_atomic(map, KM_USER0); |
2512 | page = list_entry(page->lru.prev, struct page, lru); |
2513 | } |
2514 | return true; /* incremented */ |
2515 | |
2516 | } else { /* decrementing */ |
2517 | /* |
2518 | * Think of how you subtract 1 from 1000 |
2519 | */ |
2520 | BUG_ON(count != COUNT_CONTINUED); |
2521 | while (*map == COUNT_CONTINUED) { |
2522 | kunmap_atomic(map, KM_USER0); |
2523 | page = list_entry(page->lru.next, struct page, lru); |
2524 | BUG_ON(page == head); |
2525 | map = kmap_atomic(page, KM_USER0) + offset; |
2526 | } |
2527 | BUG_ON(*map == 0); |
2528 | *map -= 1; |
2529 | if (*map == 0) |
2530 | count = 0; |
2531 | kunmap_atomic(map, KM_USER0); |
2532 | page = list_entry(page->lru.prev, struct page, lru); |
2533 | while (page != head) { |
2534 | map = kmap_atomic(page, KM_USER0) + offset; |
2535 | *map = SWAP_CONT_MAX | count; |
2536 | count = COUNT_CONTINUED; |
2537 | kunmap_atomic(map, KM_USER0); |
2538 | page = list_entry(page->lru.prev, struct page, lru); |
2539 | } |
2540 | return count == COUNT_CONTINUED; |
2541 | } |
2542 | } |
2543 | |
2544 | /* |
2545 | * free_swap_count_continuations - swapoff free all the continuation pages |
2546 | * appended to the swap_map, after swap_map is quiesced, before vfree'ing it. |
2547 | */ |
2548 | static void free_swap_count_continuations(struct swap_info_struct *si) |
2549 | { |
2550 | pgoff_t offset; |
2551 | |
2552 | for (offset = 0; offset < si->max; offset += PAGE_SIZE) { |
2553 | struct page *head; |
2554 | head = vmalloc_to_page(si->swap_map + offset); |
2555 | if (page_private(head)) { |
2556 | struct list_head *this, *next; |
2557 | list_for_each_safe(this, next, &head->lru) { |
2558 | struct page *page; |
2559 | page = list_entry(this, struct page, lru); |
2560 | list_del(this); |
2561 | __free_page(page); |
2562 | } |
2563 | } |
2564 | } |
2565 | } |
2566 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9