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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/page_io.c
4 *
5 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
6 *
7 * Swap reorganised 29.12.95,
8 * Asynchronous swapping added 30.12.95. Stephen Tweedie
9 * Removed race in async swapping. 14.4.1996. Bruno Haible
10 * Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie
11 * Always use brw_page, life becomes simpler. 12 May 1998 Eric Biederman
12 */
13
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/uio.h>
26#include <linux/sched/task.h>
27#include <asm/pgtable.h>
28
29static struct bio *get_swap_bio(gfp_t gfp_flags,
30 struct page *page, bio_end_io_t end_io)
31{
32 int i, nr = hpage_nr_pages(page);
33 struct bio *bio;
34
35 bio = bio_alloc(gfp_flags, nr);
36 if (bio) {
37 struct block_device *bdev;
38
39 bio->bi_iter.bi_sector = map_swap_page(page, &bdev);
40 bio_set_dev(bio, bdev);
41 bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
42 bio->bi_end_io = end_io;
43
44 for (i = 0; i < nr; i++)
45 bio_add_page(bio, page + i, PAGE_SIZE, 0);
46 VM_BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE * nr);
47 }
48 return bio;
49}
50
51void end_swap_bio_write(struct bio *bio)
52{
53 struct page *page = bio_first_page_all(bio);
54
55 if (bio->bi_status) {
56 SetPageError(page);
57 /*
58 * We failed to write the page out to swap-space.
59 * Re-dirty the page in order to avoid it being reclaimed.
60 * Also print a dire warning that things will go BAD (tm)
61 * very quickly.
62 *
63 * Also clear PG_reclaim to avoid rotate_reclaimable_page()
64 */
65 set_page_dirty(page);
66 pr_alert("Write-error on swap-device (%u:%u:%llu)\n",
67 MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
68 (unsigned long long)bio->bi_iter.bi_sector);
69 ClearPageReclaim(page);
70 }
71 end_page_writeback(page);
72 bio_put(bio);
73}
74
75static void swap_slot_free_notify(struct page *page)
76{
77 struct swap_info_struct *sis;
78 struct gendisk *disk;
79
80 /*
81 * There is no guarantee that the page is in swap cache - the software
82 * suspend code (at least) uses end_swap_bio_read() against a non-
83 * swapcache page. So we must check PG_swapcache before proceeding with
84 * this optimization.
85 */
86 if (unlikely(!PageSwapCache(page)))
87 return;
88
89 sis = page_swap_info(page);
90 if (!(sis->flags & SWP_BLKDEV))
91 return;
92
93 /*
94 * The swap subsystem performs lazy swap slot freeing,
95 * expecting that the page will be swapped out again.
96 * So we can avoid an unnecessary write if the page
97 * isn't redirtied.
98 * This is good for real swap storage because we can
99 * reduce unnecessary I/O and enhance wear-leveling
100 * if an SSD is used as the as swap device.
101 * But if in-memory swap device (eg zram) is used,
102 * this causes a duplicated copy between uncompressed
103 * data in VM-owned memory and compressed data in
104 * zram-owned memory. So let's free zram-owned memory
105 * and make the VM-owned decompressed page *dirty*,
106 * so the page should be swapped out somewhere again if
107 * we again wish to reclaim it.
108 */
109 disk = sis->bdev->bd_disk;
110 if (disk->fops->swap_slot_free_notify) {
111 swp_entry_t entry;
112 unsigned long offset;
113
114 entry.val = page_private(page);
115 offset = swp_offset(entry);
116
117 SetPageDirty(page);
118 disk->fops->swap_slot_free_notify(sis->bdev,
119 offset);
120 }
121}
122
123static void end_swap_bio_read(struct bio *bio)
124{
125 struct page *page = bio_first_page_all(bio);
126 struct task_struct *waiter = bio->bi_private;
127
128 if (bio->bi_status) {
129 SetPageError(page);
130 ClearPageUptodate(page);
131 pr_alert("Read-error on swap-device (%u:%u:%llu)\n",
132 MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
133 (unsigned long long)bio->bi_iter.bi_sector);
134 goto out;
135 }
136
137 SetPageUptodate(page);
138 swap_slot_free_notify(page);
139out:
140 unlock_page(page);
141 WRITE_ONCE(bio->bi_private, NULL);
142 bio_put(bio);
143 wake_up_process(waiter);
144 put_task_struct(waiter);
145}
146
147int generic_swapfile_activate(struct swap_info_struct *sis,
148 struct file *swap_file,
149 sector_t *span)
150{
151 struct address_space *mapping = swap_file->f_mapping;
152 struct inode *inode = mapping->host;
153 unsigned blocks_per_page;
154 unsigned long page_no;
155 unsigned blkbits;
156 sector_t probe_block;
157 sector_t last_block;
158 sector_t lowest_block = -1;
159 sector_t highest_block = 0;
160 int nr_extents = 0;
161 int ret;
162
163 blkbits = inode->i_blkbits;
164 blocks_per_page = PAGE_SIZE >> blkbits;
165
166 /*
167 * Map all the blocks into the extent list. This code doesn't try
168 * to be very smart.
169 */
170 probe_block = 0;
171 page_no = 0;
172 last_block = i_size_read(inode) >> blkbits;
173 while ((probe_block + blocks_per_page) <= last_block &&
174 page_no < sis->max) {
175 unsigned block_in_page;
176 sector_t first_block;
177
178 cond_resched();
179
180 first_block = bmap(inode, probe_block);
181 if (first_block == 0)
182 goto bad_bmap;
183
184 /*
185 * It must be PAGE_SIZE aligned on-disk
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 = bmap(inode, probe_block + block_in_page);
197 if (block == 0)
198 goto bad_bmap;
199 if (block != first_block + block_in_page) {
200 /* Discontiguity */
201 probe_block++;
202 goto reprobe;
203 }
204 }
205
206 first_block >>= (PAGE_SHIFT - blkbits);
207 if (page_no) { /* exclude the header page */
208 if (first_block < lowest_block)
209 lowest_block = first_block;
210 if (first_block > highest_block)
211 highest_block = first_block;
212 }
213
214 /*
215 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
216 */
217 ret = add_swap_extent(sis, page_no, 1, first_block);
218 if (ret < 0)
219 goto out;
220 nr_extents += ret;
221 page_no++;
222 probe_block += blocks_per_page;
223reprobe:
224 continue;
225 }
226 ret = nr_extents;
227 *span = 1 + highest_block - lowest_block;
228 if (page_no == 0)
229 page_no = 1; /* force Empty message */
230 sis->max = page_no;
231 sis->pages = page_no - 1;
232 sis->highest_bit = page_no - 1;
233out:
234 return ret;
235bad_bmap:
236 pr_err("swapon: swapfile has holes\n");
237 ret = -EINVAL;
238 goto out;
239}
240
241/*
242 * We may have stale swap cache pages in memory: notice
243 * them here and get rid of the unnecessary final write.
244 */
245int swap_writepage(struct page *page, struct writeback_control *wbc)
246{
247 int ret = 0;
248
249 if (try_to_free_swap(page)) {
250 unlock_page(page);
251 goto out;
252 }
253 if (frontswap_store(page) == 0) {
254 set_page_writeback(page);
255 unlock_page(page);
256 end_page_writeback(page);
257 goto out;
258 }
259 ret = __swap_writepage(page, wbc, end_swap_bio_write);
260out:
261 return ret;
262}
263
264static sector_t swap_page_sector(struct page *page)
265{
266 return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9);
267}
268
269static inline void count_swpout_vm_event(struct page *page)
270{
271#ifdef CONFIG_TRANSPARENT_HUGEPAGE
272 if (unlikely(PageTransHuge(page)))
273 count_vm_event(THP_SWPOUT);
274#endif
275 count_vm_events(PSWPOUT, hpage_nr_pages(page));
276}
277
278int __swap_writepage(struct page *page, struct writeback_control *wbc,
279 bio_end_io_t end_write_func)
280{
281 struct bio *bio;
282 int ret;
283 struct swap_info_struct *sis = page_swap_info(page);
284
285 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
286 if (sis->flags & SWP_FILE) {
287 struct kiocb kiocb;
288 struct file *swap_file = sis->swap_file;
289 struct address_space *mapping = swap_file->f_mapping;
290 struct bio_vec bv = {
291 .bv_page = page,
292 .bv_len = PAGE_SIZE,
293 .bv_offset = 0
294 };
295 struct iov_iter from;
296
297 iov_iter_bvec(&from, ITER_BVEC | WRITE, &bv, 1, PAGE_SIZE);
298 init_sync_kiocb(&kiocb, swap_file);
299 kiocb.ki_pos = page_file_offset(page);
300
301 set_page_writeback(page);
302 unlock_page(page);
303 ret = mapping->a_ops->direct_IO(&kiocb, &from);
304 if (ret == PAGE_SIZE) {
305 count_vm_event(PSWPOUT);
306 ret = 0;
307 } else {
308 /*
309 * In the case of swap-over-nfs, this can be a
310 * temporary failure if the system has limited
311 * memory for allocating transmit buffers.
312 * Mark the page dirty and avoid
313 * rotate_reclaimable_page but rate-limit the
314 * messages but do not flag PageError like
315 * the normal direct-to-bio case as it could
316 * be temporary.
317 */
318 set_page_dirty(page);
319 ClearPageReclaim(page);
320 pr_err_ratelimited("Write error on dio swapfile (%llu)\n",
321 page_file_offset(page));
322 }
323 end_page_writeback(page);
324 return ret;
325 }
326
327 ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
328 if (!ret) {
329 count_swpout_vm_event(page);
330 return 0;
331 }
332
333 ret = 0;
334 bio = get_swap_bio(GFP_NOIO, page, end_write_func);
335 if (bio == NULL) {
336 set_page_dirty(page);
337 unlock_page(page);
338 ret = -ENOMEM;
339 goto out;
340 }
341 bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
342 count_swpout_vm_event(page);
343 set_page_writeback(page);
344 unlock_page(page);
345 submit_bio(bio);
346out:
347 return ret;
348}
349
350int swap_readpage(struct page *page, bool synchronous)
351{
352 struct bio *bio;
353 int ret = 0;
354 struct swap_info_struct *sis = page_swap_info(page);
355 blk_qc_t qc;
356 struct gendisk *disk;
357
358 VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
359 VM_BUG_ON_PAGE(!PageLocked(page), page);
360 VM_BUG_ON_PAGE(PageUptodate(page), page);
361 if (frontswap_load(page) == 0) {
362 SetPageUptodate(page);
363 unlock_page(page);
364 goto out;
365 }
366
367 if (sis->flags & SWP_FILE) {
368 struct file *swap_file = sis->swap_file;
369 struct address_space *mapping = swap_file->f_mapping;
370
371 ret = mapping->a_ops->readpage(swap_file, page);
372 if (!ret)
373 count_vm_event(PSWPIN);
374 return ret;
375 }
376
377 ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
378 if (!ret) {
379 if (trylock_page(page)) {
380 swap_slot_free_notify(page);
381 unlock_page(page);
382 }
383
384 count_vm_event(PSWPIN);
385 return 0;
386 }
387
388 ret = 0;
389 bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
390 if (bio == NULL) {
391 unlock_page(page);
392 ret = -ENOMEM;
393 goto out;
394 }
395 disk = bio->bi_disk;
396 /*
397 * Keep this task valid during swap readpage because the oom killer may
398 * attempt to access it in the page fault retry time check.
399 */
400 get_task_struct(current);
401 bio->bi_private = current;
402 bio_set_op_attrs(bio, REQ_OP_READ, 0);
403 count_vm_event(PSWPIN);
404 bio_get(bio);
405 qc = submit_bio(bio);
406 while (synchronous) {
407 set_current_state(TASK_UNINTERRUPTIBLE);
408 if (!READ_ONCE(bio->bi_private))
409 break;
410
411 if (!blk_poll(disk->queue, qc))
412 break;
413 }
414 __set_current_state(TASK_RUNNING);
415 bio_put(bio);
416
417out:
418 return ret;
419}
420
421int swap_set_page_dirty(struct page *page)
422{
423 struct swap_info_struct *sis = page_swap_info(page);
424
425 if (sis->flags & SWP_FILE) {
426 struct address_space *mapping = sis->swap_file->f_mapping;
427
428 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
429 return mapping->a_ops->set_page_dirty(page);
430 } else {
431 return __set_page_dirty_no_writeback(page);
432 }
433}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/page_io.c
4 *
5 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
6 *
7 * Swap reorganised 29.12.95,
8 * Asynchronous swapping added 30.12.95. Stephen Tweedie
9 * Removed race in async swapping. 14.4.1996. Bruno Haible
10 * Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie
11 * Always use brw_page, life becomes simpler. 12 May 1998 Eric Biederman
12 */
13
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
29void end_swap_bio_write(struct bio *bio)
30{
31 struct page *page = bio_first_page_all(bio);
32
33 if (bio->bi_status) {
34 SetPageError(page);
35 /*
36 * We failed to write the page out to swap-space.
37 * Re-dirty the page in order to avoid it being reclaimed.
38 * Also print a dire warning that things will go BAD (tm)
39 * very quickly.
40 *
41 * Also clear PG_reclaim to avoid rotate_reclaimable_page()
42 */
43 set_page_dirty(page);
44 pr_alert_ratelimited("Write-error on swap-device (%u:%u:%llu)\n",
45 MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
46 (unsigned long long)bio->bi_iter.bi_sector);
47 ClearPageReclaim(page);
48 }
49 end_page_writeback(page);
50 bio_put(bio);
51}
52
53static void swap_slot_free_notify(struct page *page)
54{
55 struct swap_info_struct *sis;
56 struct gendisk *disk;
57 swp_entry_t entry;
58
59 /*
60 * There is no guarantee that the page is in swap cache - the software
61 * suspend code (at least) uses end_swap_bio_read() against a non-
62 * swapcache page. So we must check PG_swapcache before proceeding with
63 * this optimization.
64 */
65 if (unlikely(!PageSwapCache(page)))
66 return;
67
68 sis = page_swap_info(page);
69 if (data_race(!(sis->flags & SWP_BLKDEV)))
70 return;
71
72 /*
73 * The swap subsystem performs lazy swap slot freeing,
74 * expecting that the page will be swapped out again.
75 * So we can avoid an unnecessary write if the page
76 * isn't redirtied.
77 * This is good for real swap storage because we can
78 * reduce unnecessary I/O and enhance wear-leveling
79 * if an SSD is used as the as swap device.
80 * But if in-memory swap device (eg zram) is used,
81 * this causes a duplicated copy between uncompressed
82 * data in VM-owned memory and compressed data in
83 * zram-owned memory. So let's free zram-owned memory
84 * and make the VM-owned decompressed page *dirty*,
85 * so the page should be swapped out somewhere again if
86 * we again wish to reclaim it.
87 */
88 disk = sis->bdev->bd_disk;
89 entry.val = page_private(page);
90 if (disk->fops->swap_slot_free_notify && __swap_count(entry) == 1) {
91 unsigned long offset;
92
93 offset = swp_offset(entry);
94
95 SetPageDirty(page);
96 disk->fops->swap_slot_free_notify(sis->bdev,
97 offset);
98 }
99}
100
101static void end_swap_bio_read(struct bio *bio)
102{
103 struct page *page = bio_first_page_all(bio);
104 struct task_struct *waiter = bio->bi_private;
105
106 if (bio->bi_status) {
107 SetPageError(page);
108 ClearPageUptodate(page);
109 pr_alert_ratelimited("Read-error on swap-device (%u:%u:%llu)\n",
110 MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
111 (unsigned long long)bio->bi_iter.bi_sector);
112 goto out;
113 }
114
115 SetPageUptodate(page);
116 swap_slot_free_notify(page);
117out:
118 unlock_page(page);
119 WRITE_ONCE(bio->bi_private, NULL);
120 bio_put(bio);
121 if (waiter) {
122 blk_wake_io_task(waiter);
123 put_task_struct(waiter);
124 }
125}
126
127int generic_swapfile_activate(struct swap_info_struct *sis,
128 struct file *swap_file,
129 sector_t *span)
130{
131 struct address_space *mapping = swap_file->f_mapping;
132 struct inode *inode = mapping->host;
133 unsigned blocks_per_page;
134 unsigned long page_no;
135 unsigned blkbits;
136 sector_t probe_block;
137 sector_t last_block;
138 sector_t lowest_block = -1;
139 sector_t highest_block = 0;
140 int nr_extents = 0;
141 int ret;
142
143 blkbits = inode->i_blkbits;
144 blocks_per_page = PAGE_SIZE >> blkbits;
145
146 /*
147 * Map all the blocks into the extent tree. This code doesn't try
148 * to be very smart.
149 */
150 probe_block = 0;
151 page_no = 0;
152 last_block = i_size_read(inode) >> blkbits;
153 while ((probe_block + blocks_per_page) <= last_block &&
154 page_no < sis->max) {
155 unsigned block_in_page;
156 sector_t first_block;
157
158 cond_resched();
159
160 first_block = probe_block;
161 ret = bmap(inode, &first_block);
162 if (ret || !first_block)
163 goto bad_bmap;
164
165 /*
166 * It must be PAGE_SIZE aligned on-disk
167 */
168 if (first_block & (blocks_per_page - 1)) {
169 probe_block++;
170 goto reprobe;
171 }
172
173 for (block_in_page = 1; block_in_page < blocks_per_page;
174 block_in_page++) {
175 sector_t block;
176
177 block = probe_block + block_in_page;
178 ret = bmap(inode, &block);
179 if (ret || !block)
180 goto bad_bmap;
181
182 if (block != first_block + block_in_page) {
183 /* Discontiguity */
184 probe_block++;
185 goto reprobe;
186 }
187 }
188
189 first_block >>= (PAGE_SHIFT - blkbits);
190 if (page_no) { /* exclude the header page */
191 if (first_block < lowest_block)
192 lowest_block = first_block;
193 if (first_block > highest_block)
194 highest_block = first_block;
195 }
196
197 /*
198 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
199 */
200 ret = add_swap_extent(sis, page_no, 1, first_block);
201 if (ret < 0)
202 goto out;
203 nr_extents += ret;
204 page_no++;
205 probe_block += blocks_per_page;
206reprobe:
207 continue;
208 }
209 ret = nr_extents;
210 *span = 1 + highest_block - lowest_block;
211 if (page_no == 0)
212 page_no = 1; /* force Empty message */
213 sis->max = page_no;
214 sis->pages = page_no - 1;
215 sis->highest_bit = page_no - 1;
216out:
217 return ret;
218bad_bmap:
219 pr_err("swapon: swapfile has holes\n");
220 ret = -EINVAL;
221 goto out;
222}
223
224/*
225 * We may have stale swap cache pages in memory: notice
226 * them here and get rid of the unnecessary final write.
227 */
228int swap_writepage(struct page *page, struct writeback_control *wbc)
229{
230 int ret = 0;
231
232 if (try_to_free_swap(page)) {
233 unlock_page(page);
234 goto out;
235 }
236 /*
237 * Arch code may have to preserve more data than just the page
238 * contents, e.g. memory tags.
239 */
240 ret = arch_prepare_to_swap(page);
241 if (ret) {
242 set_page_dirty(page);
243 unlock_page(page);
244 goto out;
245 }
246 if (frontswap_store(page) == 0) {
247 set_page_writeback(page);
248 unlock_page(page);
249 end_page_writeback(page);
250 goto out;
251 }
252 ret = __swap_writepage(page, wbc, end_swap_bio_write);
253out:
254 return ret;
255}
256
257static inline void count_swpout_vm_event(struct page *page)
258{
259#ifdef CONFIG_TRANSPARENT_HUGEPAGE
260 if (unlikely(PageTransHuge(page)))
261 count_vm_event(THP_SWPOUT);
262#endif
263 count_vm_events(PSWPOUT, thp_nr_pages(page));
264}
265
266#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
267static void bio_associate_blkg_from_page(struct bio *bio, struct page *page)
268{
269 struct cgroup_subsys_state *css;
270 struct mem_cgroup *memcg;
271
272 memcg = page_memcg(page);
273 if (!memcg)
274 return;
275
276 rcu_read_lock();
277 css = cgroup_e_css(memcg->css.cgroup, &io_cgrp_subsys);
278 bio_associate_blkg_from_css(bio, css);
279 rcu_read_unlock();
280}
281#else
282#define bio_associate_blkg_from_page(bio, page) do { } while (0)
283#endif /* CONFIG_MEMCG && CONFIG_BLK_CGROUP */
284
285int __swap_writepage(struct page *page, struct writeback_control *wbc,
286 bio_end_io_t end_write_func)
287{
288 struct bio *bio;
289 int ret;
290 struct swap_info_struct *sis = page_swap_info(page);
291
292 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
293 if (data_race(sis->flags & SWP_FS_OPS)) {
294 struct kiocb kiocb;
295 struct file *swap_file = sis->swap_file;
296 struct address_space *mapping = swap_file->f_mapping;
297 struct bio_vec bv = {
298 .bv_page = page,
299 .bv_len = PAGE_SIZE,
300 .bv_offset = 0
301 };
302 struct iov_iter from;
303
304 iov_iter_bvec(&from, WRITE, &bv, 1, PAGE_SIZE);
305 init_sync_kiocb(&kiocb, swap_file);
306 kiocb.ki_pos = page_file_offset(page);
307
308 set_page_writeback(page);
309 unlock_page(page);
310 ret = mapping->a_ops->direct_IO(&kiocb, &from);
311 if (ret == PAGE_SIZE) {
312 count_vm_event(PSWPOUT);
313 ret = 0;
314 } else {
315 /*
316 * In the case of swap-over-nfs, this can be a
317 * temporary failure if the system has limited
318 * memory for allocating transmit buffers.
319 * Mark the page dirty and avoid
320 * rotate_reclaimable_page but rate-limit the
321 * messages but do not flag PageError like
322 * the normal direct-to-bio case as it could
323 * be temporary.
324 */
325 set_page_dirty(page);
326 ClearPageReclaim(page);
327 pr_err_ratelimited("Write error on dio swapfile (%llu)\n",
328 page_file_offset(page));
329 }
330 end_page_writeback(page);
331 return ret;
332 }
333
334 ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
335 if (!ret) {
336 count_swpout_vm_event(page);
337 return 0;
338 }
339
340 bio = bio_alloc(GFP_NOIO, 1);
341 bio_set_dev(bio, sis->bdev);
342 bio->bi_iter.bi_sector = swap_page_sector(page);
343 bio->bi_opf = REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc);
344 bio->bi_end_io = end_write_func;
345 bio_add_page(bio, page, thp_size(page), 0);
346
347 bio_associate_blkg_from_page(bio, page);
348 count_swpout_vm_event(page);
349 set_page_writeback(page);
350 unlock_page(page);
351 submit_bio(bio);
352
353 return 0;
354}
355
356int swap_readpage(struct page *page, bool synchronous)
357{
358 struct bio *bio;
359 int ret = 0;
360 struct swap_info_struct *sis = page_swap_info(page);
361 blk_qc_t qc;
362 struct gendisk *disk;
363 unsigned long pflags;
364
365 VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
366 VM_BUG_ON_PAGE(!PageLocked(page), page);
367 VM_BUG_ON_PAGE(PageUptodate(page), page);
368
369 /*
370 * Count submission time as memory stall. When the device is congested,
371 * or the submitting cgroup IO-throttled, submission can be a
372 * significant part of overall IO time.
373 */
374 psi_memstall_enter(&pflags);
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 disk = bio->bi_bdev->bd_disk;
414 /*
415 * Keep this task valid during swap readpage because the oom killer may
416 * attempt to access it in the page fault retry time check.
417 */
418 if (synchronous) {
419 bio->bi_opf |= REQ_HIPRI;
420 get_task_struct(current);
421 bio->bi_private = current;
422 }
423 count_vm_event(PSWPIN);
424 bio_get(bio);
425 qc = submit_bio(bio);
426 while (synchronous) {
427 set_current_state(TASK_UNINTERRUPTIBLE);
428 if (!READ_ONCE(bio->bi_private))
429 break;
430
431 if (!blk_poll(disk->queue, qc, true))
432 blk_io_schedule();
433 }
434 __set_current_state(TASK_RUNNING);
435 bio_put(bio);
436
437out:
438 psi_memstall_leave(&pflags);
439 return ret;
440}
441
442int swap_set_page_dirty(struct page *page)
443{
444 struct swap_info_struct *sis = page_swap_info(page);
445
446 if (data_race(sis->flags & SWP_FS_OPS)) {
447 struct address_space *mapping = sis->swap_file->f_mapping;
448
449 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
450 return mapping->a_ops->set_page_dirty(page);
451 } else {
452 return __set_page_dirty_no_writeback(page);
453 }
454}