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14#include <linux/mm.h>
15#include <linux/kernel_stat.h>
16#include <linux/gfp.h>
17#include <linux/pagemap.h>
18#include <linux/swap.h>
19#include <linux/bio.h>
20#include <linux/swapops.h>
21#include <linux/buffer_head.h>
22#include <linux/writeback.h>
23#include <linux/frontswap.h>
24#include <linux/blkdev.h>
25#include <linux/psi.h>
26#include <linux/uio.h>
27#include <linux/sched/task.h>
28#include <linux/delayacct.h>
29
30void end_swap_bio_write(struct bio *bio)
31{
32 struct page *page = bio_first_page_all(bio);
33
34 if (bio->bi_status) {
35 SetPageError(page);
36
37
38
39
40
41
42
43
44 set_page_dirty(page);
45 pr_alert_ratelimited("Write-error on swap-device (%u:%u:%llu)\n",
46 MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
47 (unsigned long long)bio->bi_iter.bi_sector);
48 ClearPageReclaim(page);
49 }
50 end_page_writeback(page);
51 bio_put(bio);
52}
53
54static void swap_slot_free_notify(struct page *page)
55{
56 struct swap_info_struct *sis;
57 struct gendisk *disk;
58 swp_entry_t entry;
59
60
61
62
63
64
65
66 if (unlikely(!PageSwapCache(page)))
67 return;
68
69 sis = page_swap_info(page);
70 if (data_race(!(sis->flags & SWP_BLKDEV)))
71 return;
72
73
74
75
76
77
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79
80
81
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83
84
85
86
87
88
89 disk = sis->bdev->bd_disk;
90 entry.val = page_private(page);
91 if (disk->fops->swap_slot_free_notify && __swap_count(entry) == 1) {
92 unsigned long offset;
93
94 offset = swp_offset(entry);
95
96 SetPageDirty(page);
97 disk->fops->swap_slot_free_notify(sis->bdev,
98 offset);
99 }
100}
101
102static void end_swap_bio_read(struct bio *bio)
103{
104 struct page *page = bio_first_page_all(bio);
105 struct task_struct *waiter = bio->bi_private;
106
107 if (bio->bi_status) {
108 SetPageError(page);
109 ClearPageUptodate(page);
110 pr_alert_ratelimited("Read-error on swap-device (%u:%u:%llu)\n",
111 MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
112 (unsigned long long)bio->bi_iter.bi_sector);
113 goto out;
114 }
115
116 SetPageUptodate(page);
117 swap_slot_free_notify(page);
118out:
119 unlock_page(page);
120 WRITE_ONCE(bio->bi_private, NULL);
121 bio_put(bio);
122 if (waiter) {
123 blk_wake_io_task(waiter);
124 put_task_struct(waiter);
125 }
126}
127
128int generic_swapfile_activate(struct swap_info_struct *sis,
129 struct file *swap_file,
130 sector_t *span)
131{
132 struct address_space *mapping = swap_file->f_mapping;
133 struct inode *inode = mapping->host;
134 unsigned blocks_per_page;
135 unsigned long page_no;
136 unsigned blkbits;
137 sector_t probe_block;
138 sector_t last_block;
139 sector_t lowest_block = -1;
140 sector_t highest_block = 0;
141 int nr_extents = 0;
142 int ret;
143
144 blkbits = inode->i_blkbits;
145 blocks_per_page = PAGE_SIZE >> blkbits;
146
147
148
149
150
151 probe_block = 0;
152 page_no = 0;
153 last_block = i_size_read(inode) >> blkbits;
154 while ((probe_block + blocks_per_page) <= last_block &&
155 page_no < sis->max) {
156 unsigned block_in_page;
157 sector_t first_block;
158
159 cond_resched();
160
161 first_block = probe_block;
162 ret = bmap(inode, &first_block);
163 if (ret || !first_block)
164 goto bad_bmap;
165
166
167
168
169 if (first_block & (blocks_per_page - 1)) {
170 probe_block++;
171 goto reprobe;
172 }
173
174 for (block_in_page = 1; block_in_page < blocks_per_page;
175 block_in_page++) {
176 sector_t block;
177
178 block = probe_block + block_in_page;
179 ret = bmap(inode, &block);
180 if (ret || !block)
181 goto bad_bmap;
182
183 if (block != first_block + block_in_page) {
184
185 probe_block++;
186 goto reprobe;
187 }
188 }
189
190 first_block >>= (PAGE_SHIFT - blkbits);
191 if (page_no) {
192 if (first_block < lowest_block)
193 lowest_block = first_block;
194 if (first_block > highest_block)
195 highest_block = first_block;
196 }
197
198
199
200
201 ret = add_swap_extent(sis, page_no, 1, first_block);
202 if (ret < 0)
203 goto out;
204 nr_extents += ret;
205 page_no++;
206 probe_block += blocks_per_page;
207reprobe:
208 continue;
209 }
210 ret = nr_extents;
211 *span = 1 + highest_block - lowest_block;
212 if (page_no == 0)
213 page_no = 1;
214 sis->max = page_no;
215 sis->pages = page_no - 1;
216 sis->highest_bit = page_no - 1;
217out:
218 return ret;
219bad_bmap:
220 pr_err("swapon: swapfile has holes\n");
221 ret = -EINVAL;
222 goto out;
223}
224
225
226
227
228
229int swap_writepage(struct page *page, struct writeback_control *wbc)
230{
231 int ret = 0;
232
233 if (try_to_free_swap(page)) {
234 unlock_page(page);
235 goto out;
236 }
237
238
239
240
241 ret = arch_prepare_to_swap(page);
242 if (ret) {
243 set_page_dirty(page);
244 unlock_page(page);
245 goto out;
246 }
247 if (frontswap_store(page) == 0) {
248 set_page_writeback(page);
249 unlock_page(page);
250 end_page_writeback(page);
251 goto out;
252 }
253 ret = __swap_writepage(page, wbc, end_swap_bio_write);
254out:
255 return ret;
256}
257
258static inline void count_swpout_vm_event(struct page *page)
259{
260#ifdef CONFIG_TRANSPARENT_HUGEPAGE
261 if (unlikely(PageTransHuge(page)))
262 count_vm_event(THP_SWPOUT);
263#endif
264 count_vm_events(PSWPOUT, thp_nr_pages(page));
265}
266
267#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
268static void bio_associate_blkg_from_page(struct bio *bio, struct page *page)
269{
270 struct cgroup_subsys_state *css;
271 struct mem_cgroup *memcg;
272
273 memcg = page_memcg(page);
274 if (!memcg)
275 return;
276
277 rcu_read_lock();
278 css = cgroup_e_css(memcg->css.cgroup, &io_cgrp_subsys);
279 bio_associate_blkg_from_css(bio, css);
280 rcu_read_unlock();
281}
282#else
283#define bio_associate_blkg_from_page(bio, page) do { } while (0)
284#endif
285
286int __swap_writepage(struct page *page, struct writeback_control *wbc,
287 bio_end_io_t end_write_func)
288{
289 struct bio *bio;
290 int ret;
291 struct swap_info_struct *sis = page_swap_info(page);
292
293 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
294 if (data_race(sis->flags & SWP_FS_OPS)) {
295 struct kiocb kiocb;
296 struct file *swap_file = sis->swap_file;
297 struct address_space *mapping = swap_file->f_mapping;
298 struct bio_vec bv = {
299 .bv_page = page,
300 .bv_len = PAGE_SIZE,
301 .bv_offset = 0
302 };
303 struct iov_iter from;
304
305 iov_iter_bvec(&from, WRITE, &bv, 1, PAGE_SIZE);
306 init_sync_kiocb(&kiocb, swap_file);
307 kiocb.ki_pos = page_file_offset(page);
308
309 set_page_writeback(page);
310 unlock_page(page);
311 ret = mapping->a_ops->direct_IO(&kiocb, &from);
312 if (ret == PAGE_SIZE) {
313 count_vm_event(PSWPOUT);
314 ret = 0;
315 } else {
316
317
318
319
320
321
322
323
324
325
326 set_page_dirty(page);
327 ClearPageReclaim(page);
328 pr_err_ratelimited("Write error on dio swapfile (%llu)\n",
329 page_file_offset(page));
330 }
331 end_page_writeback(page);
332 return ret;
333 }
334
335 ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
336 if (!ret) {
337 count_swpout_vm_event(page);
338 return 0;
339 }
340
341 bio = bio_alloc(GFP_NOIO, 1);
342 bio_set_dev(bio, sis->bdev);
343 bio->bi_iter.bi_sector = swap_page_sector(page);
344 bio->bi_opf = REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc);
345 bio->bi_end_io = end_write_func;
346 bio_add_page(bio, page, thp_size(page), 0);
347
348 bio_associate_blkg_from_page(bio, page);
349 count_swpout_vm_event(page);
350 set_page_writeback(page);
351 unlock_page(page);
352 submit_bio(bio);
353
354 return 0;
355}
356
357int swap_readpage(struct page *page, bool synchronous)
358{
359 struct bio *bio;
360 int ret = 0;
361 struct swap_info_struct *sis = page_swap_info(page);
362 unsigned long pflags;
363
364 VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
365 VM_BUG_ON_PAGE(!PageLocked(page), page);
366 VM_BUG_ON_PAGE(PageUptodate(page), page);
367
368
369
370
371
372
373 psi_memstall_enter(&pflags);
374 delayacct_swapin_start();
375
376 if (frontswap_load(page) == 0) {
377 SetPageUptodate(page);
378 unlock_page(page);
379 goto out;
380 }
381
382 if (data_race(sis->flags & SWP_FS_OPS)) {
383 struct file *swap_file = sis->swap_file;
384 struct address_space *mapping = swap_file->f_mapping;
385
386 ret = mapping->a_ops->readpage(swap_file, page);
387 if (!ret)
388 count_vm_event(PSWPIN);
389 goto out;
390 }
391
392 if (sis->flags & SWP_SYNCHRONOUS_IO) {
393 ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
394 if (!ret) {
395 if (trylock_page(page)) {
396 swap_slot_free_notify(page);
397 unlock_page(page);
398 }
399
400 count_vm_event(PSWPIN);
401 goto out;
402 }
403 }
404
405 ret = 0;
406 bio = bio_alloc(GFP_KERNEL, 1);
407 bio_set_dev(bio, sis->bdev);
408 bio->bi_opf = REQ_OP_READ;
409 bio->bi_iter.bi_sector = swap_page_sector(page);
410 bio->bi_end_io = end_swap_bio_read;
411 bio_add_page(bio, page, thp_size(page), 0);
412
413
414
415
416 if (synchronous) {
417 bio->bi_opf |= REQ_POLLED;
418 get_task_struct(current);
419 bio->bi_private = current;
420 }
421 count_vm_event(PSWPIN);
422 bio_get(bio);
423 submit_bio(bio);
424 while (synchronous) {
425 set_current_state(TASK_UNINTERRUPTIBLE);
426 if (!READ_ONCE(bio->bi_private))
427 break;
428
429 if (!bio_poll(bio, NULL, 0))
430 blk_io_schedule();
431 }
432 __set_current_state(TASK_RUNNING);
433 bio_put(bio);
434
435out:
436 psi_memstall_leave(&pflags);
437 delayacct_swapin_end();
438 return ret;
439}
440
441int swap_set_page_dirty(struct page *page)
442{
443 struct swap_info_struct *sis = page_swap_info(page);
444
445 if (data_race(sis->flags & SWP_FS_OPS)) {
446 struct address_space *mapping = sis->swap_file->f_mapping;
447
448 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
449 return mapping->a_ops->set_page_dirty(page);
450 } else {
451 return __set_page_dirty_no_writeback(page);
452 }
453}
454