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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
29static struct bio *get_swap_bio(gfp_t gfp_flags,
30 struct page *page, bio_end_io_t end_io)
31{
32 struct bio *bio;
33
34 bio = bio_alloc(gfp_flags, 1);
35 if (bio) {
36 struct block_device *bdev;
37
38 bio->bi_iter.bi_sector = map_swap_page(page, &bdev);
39 bio_set_dev(bio, bdev);
40 bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
41 bio->bi_end_io = end_io;
42
43 bio_add_page(bio, page, thp_size(page), 0);
44 }
45 return bio;
46}
47
48void end_swap_bio_write(struct bio *bio)
49{
50 struct page *page = bio_first_page_all(bio);
51
52 if (bio->bi_status) {
53 SetPageError(page);
54
55
56
57
58
59
60
61
62 set_page_dirty(page);
63 pr_alert("Write-error on swap-device (%u:%u:%llu)\n",
64 MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
65 (unsigned long long)bio->bi_iter.bi_sector);
66 ClearPageReclaim(page);
67 }
68 end_page_writeback(page);
69 bio_put(bio);
70}
71
72static void swap_slot_free_notify(struct page *page)
73{
74 struct swap_info_struct *sis;
75 struct gendisk *disk;
76 swp_entry_t entry;
77
78
79
80
81
82
83
84 if (unlikely(!PageSwapCache(page)))
85 return;
86
87 sis = page_swap_info(page);
88 if (data_race(!(sis->flags & SWP_BLKDEV)))
89 return;
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107 disk = sis->bdev->bd_disk;
108 entry.val = page_private(page);
109 if (disk->fops->swap_slot_free_notify && __swap_count(entry) == 1) {
110 unsigned long offset;
111
112 offset = swp_offset(entry);
113
114 SetPageDirty(page);
115 disk->fops->swap_slot_free_notify(sis->bdev,
116 offset);
117 }
118}
119
120static void end_swap_bio_read(struct bio *bio)
121{
122 struct page *page = bio_first_page_all(bio);
123 struct task_struct *waiter = bio->bi_private;
124
125 if (bio->bi_status) {
126 SetPageError(page);
127 ClearPageUptodate(page);
128 pr_alert("Read-error on swap-device (%u:%u:%llu)\n",
129 MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
130 (unsigned long long)bio->bi_iter.bi_sector);
131 goto out;
132 }
133
134 SetPageUptodate(page);
135 swap_slot_free_notify(page);
136out:
137 unlock_page(page);
138 WRITE_ONCE(bio->bi_private, NULL);
139 bio_put(bio);
140 if (waiter) {
141 blk_wake_io_task(waiter);
142 put_task_struct(waiter);
143 }
144}
145
146int generic_swapfile_activate(struct swap_info_struct *sis,
147 struct file *swap_file,
148 sector_t *span)
149{
150 struct address_space *mapping = swap_file->f_mapping;
151 struct inode *inode = mapping->host;
152 unsigned blocks_per_page;
153 unsigned long page_no;
154 unsigned blkbits;
155 sector_t probe_block;
156 sector_t last_block;
157 sector_t lowest_block = -1;
158 sector_t highest_block = 0;
159 int nr_extents = 0;
160 int ret;
161
162 blkbits = inode->i_blkbits;
163 blocks_per_page = PAGE_SIZE >> blkbits;
164
165
166
167
168
169 probe_block = 0;
170 page_no = 0;
171 last_block = i_size_read(inode) >> blkbits;
172 while ((probe_block + blocks_per_page) <= last_block &&
173 page_no < sis->max) {
174 unsigned block_in_page;
175 sector_t first_block;
176
177 cond_resched();
178
179 first_block = probe_block;
180 ret = bmap(inode, &first_block);
181 if (ret || !first_block)
182 goto bad_bmap;
183
184
185
186
187 if (first_block & (blocks_per_page - 1)) {
188 probe_block++;
189 goto reprobe;
190 }
191
192 for (block_in_page = 1; block_in_page < blocks_per_page;
193 block_in_page++) {
194 sector_t block;
195
196 block = probe_block + block_in_page;
197 ret = bmap(inode, &block);
198 if (ret || !block)
199 goto bad_bmap;
200
201 if (block != first_block + block_in_page) {
202
203 probe_block++;
204 goto reprobe;
205 }
206 }
207
208 first_block >>= (PAGE_SHIFT - blkbits);
209 if (page_no) {
210 if (first_block < lowest_block)
211 lowest_block = first_block;
212 if (first_block > highest_block)
213 highest_block = first_block;
214 }
215
216
217
218
219 ret = add_swap_extent(sis, page_no, 1, first_block);
220 if (ret < 0)
221 goto out;
222 nr_extents += ret;
223 page_no++;
224 probe_block += blocks_per_page;
225reprobe:
226 continue;
227 }
228 ret = nr_extents;
229 *span = 1 + highest_block - lowest_block;
230 if (page_no == 0)
231 page_no = 1;
232 sis->max = page_no;
233 sis->pages = page_no - 1;
234 sis->highest_bit = page_no - 1;
235out:
236 return ret;
237bad_bmap:
238 pr_err("swapon: swapfile has holes\n");
239 ret = -EINVAL;
240 goto out;
241}
242
243
244
245
246
247int swap_writepage(struct page *page, struct writeback_control *wbc)
248{
249 int ret = 0;
250
251 if (try_to_free_swap(page)) {
252 unlock_page(page);
253 goto out;
254 }
255
256
257
258
259 ret = arch_prepare_to_swap(page);
260 if (ret) {
261 set_page_dirty(page);
262 unlock_page(page);
263 goto out;
264 }
265 if (frontswap_store(page) == 0) {
266 set_page_writeback(page);
267 unlock_page(page);
268 end_page_writeback(page);
269 goto out;
270 }
271 ret = __swap_writepage(page, wbc, end_swap_bio_write);
272out:
273 return ret;
274}
275
276static sector_t swap_page_sector(struct page *page)
277{
278 return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9);
279}
280
281static inline void count_swpout_vm_event(struct page *page)
282{
283#ifdef CONFIG_TRANSPARENT_HUGEPAGE
284 if (unlikely(PageTransHuge(page)))
285 count_vm_event(THP_SWPOUT);
286#endif
287 count_vm_events(PSWPOUT, thp_nr_pages(page));
288}
289
290#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
291static void bio_associate_blkg_from_page(struct bio *bio, struct page *page)
292{
293 struct cgroup_subsys_state *css;
294
295 if (!page->mem_cgroup)
296 return;
297
298 rcu_read_lock();
299 css = cgroup_e_css(page->mem_cgroup->css.cgroup, &io_cgrp_subsys);
300 bio_associate_blkg_from_css(bio, css);
301 rcu_read_unlock();
302}
303#else
304#define bio_associate_blkg_from_page(bio, page) do { } while (0)
305#endif
306
307int __swap_writepage(struct page *page, struct writeback_control *wbc,
308 bio_end_io_t end_write_func)
309{
310 struct bio *bio;
311 int ret;
312 struct swap_info_struct *sis = page_swap_info(page);
313
314 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
315 if (data_race(sis->flags & SWP_FS_OPS)) {
316 struct kiocb kiocb;
317 struct file *swap_file = sis->swap_file;
318 struct address_space *mapping = swap_file->f_mapping;
319 struct bio_vec bv = {
320 .bv_page = page,
321 .bv_len = PAGE_SIZE,
322 .bv_offset = 0
323 };
324 struct iov_iter from;
325
326 iov_iter_bvec(&from, WRITE, &bv, 1, PAGE_SIZE);
327 init_sync_kiocb(&kiocb, swap_file);
328 kiocb.ki_pos = page_file_offset(page);
329
330 set_page_writeback(page);
331 unlock_page(page);
332 ret = mapping->a_ops->direct_IO(&kiocb, &from);
333 if (ret == PAGE_SIZE) {
334 count_vm_event(PSWPOUT);
335 ret = 0;
336 } else {
337
338
339
340
341
342
343
344
345
346
347 set_page_dirty(page);
348 ClearPageReclaim(page);
349 pr_err_ratelimited("Write error on dio swapfile (%llu)\n",
350 page_file_offset(page));
351 }
352 end_page_writeback(page);
353 return ret;
354 }
355
356 ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
357 if (!ret) {
358 count_swpout_vm_event(page);
359 return 0;
360 }
361
362 bio = get_swap_bio(GFP_NOIO, page, end_write_func);
363 if (bio == NULL) {
364 set_page_dirty(page);
365 unlock_page(page);
366 return -ENOMEM;
367 }
368 bio->bi_opf = REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc);
369 bio_associate_blkg_from_page(bio, page);
370 count_swpout_vm_event(page);
371 set_page_writeback(page);
372 unlock_page(page);
373 submit_bio(bio);
374
375 return 0;
376}
377
378int swap_readpage(struct page *page, bool synchronous)
379{
380 struct bio *bio;
381 int ret = 0;
382 struct swap_info_struct *sis = page_swap_info(page);
383 blk_qc_t qc;
384 struct gendisk *disk;
385 unsigned long pflags;
386
387 VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
388 VM_BUG_ON_PAGE(!PageLocked(page), page);
389 VM_BUG_ON_PAGE(PageUptodate(page), page);
390
391
392
393
394
395
396 psi_memstall_enter(&pflags);
397
398 if (frontswap_load(page) == 0) {
399 SetPageUptodate(page);
400 unlock_page(page);
401 goto out;
402 }
403
404 if (data_race(sis->flags & SWP_FS_OPS)) {
405 struct file *swap_file = sis->swap_file;
406 struct address_space *mapping = swap_file->f_mapping;
407
408 ret = mapping->a_ops->readpage(swap_file, page);
409 if (!ret)
410 count_vm_event(PSWPIN);
411 goto out;
412 }
413
414 if (sis->flags & SWP_SYNCHRONOUS_IO) {
415 ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
416 if (!ret) {
417 if (trylock_page(page)) {
418 swap_slot_free_notify(page);
419 unlock_page(page);
420 }
421
422 count_vm_event(PSWPIN);
423 goto out;
424 }
425 }
426
427 ret = 0;
428 bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
429 if (bio == NULL) {
430 unlock_page(page);
431 ret = -ENOMEM;
432 goto out;
433 }
434 disk = bio->bi_disk;
435
436
437
438
439 bio_set_op_attrs(bio, REQ_OP_READ, 0);
440 if (synchronous) {
441 bio->bi_opf |= REQ_HIPRI;
442 get_task_struct(current);
443 bio->bi_private = current;
444 }
445 count_vm_event(PSWPIN);
446 bio_get(bio);
447 qc = submit_bio(bio);
448 while (synchronous) {
449 set_current_state(TASK_UNINTERRUPTIBLE);
450 if (!READ_ONCE(bio->bi_private))
451 break;
452
453 if (!blk_poll(disk->queue, qc, true))
454 blk_io_schedule();
455 }
456 __set_current_state(TASK_RUNNING);
457 bio_put(bio);
458
459out:
460 psi_memstall_leave(&pflags);
461 return ret;
462}
463
464int swap_set_page_dirty(struct page *page)
465{
466 struct swap_info_struct *sis = page_swap_info(page);
467
468 if (data_race(sis->flags & SWP_FS_OPS)) {
469 struct address_space *mapping = sis->swap_file->f_mapping;
470
471 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
472 return mapping->a_ops->set_page_dirty(page);
473 } else {
474 return __set_page_dirty_no_writeback(page);
475 }
476}
477