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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 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, PAGE_SIZE * hpage_nr_pages(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 * We failed to write the page out to swap-space.
56 * Re-dirty the page in order to avoid it being reclaimed.
57 * Also print a dire warning that things will go BAD (tm)
58 * very quickly.
59 *
60 * Also clear PG_reclaim to avoid rotate_reclaimable_page()
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 * There is no guarantee that the page is in swap cache - the software
80 * suspend code (at least) uses end_swap_bio_read() against a non-
81 * swapcache page. So we must check PG_swapcache before proceeding with
82 * this optimization.
83 */
84 if (unlikely(!PageSwapCache(page)))
85 return;
86
87 sis = page_swap_info(page);
88 if (!(sis->flags & SWP_BLKDEV))
89 return;
90
91 /*
92 * The swap subsystem performs lazy swap slot freeing,
93 * expecting that the page will be swapped out again.
94 * So we can avoid an unnecessary write if the page
95 * isn't redirtied.
96 * This is good for real swap storage because we can
97 * reduce unnecessary I/O and enhance wear-leveling
98 * if an SSD is used as the as swap device.
99 * But if in-memory swap device (eg zram) is used,
100 * this causes a duplicated copy between uncompressed
101 * data in VM-owned memory and compressed data in
102 * zram-owned memory. So let's free zram-owned memory
103 * and make the VM-owned decompressed page *dirty*,
104 * so the page should be swapped out somewhere again if
105 * we again wish to reclaim it.
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 * Map all the blocks into the extent tree. This code doesn't try
167 * to be very smart.
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 = bmap(inode, probe_block);
180 if (first_block == 0)
181 goto bad_bmap;
182
183 /*
184 * It must be PAGE_SIZE aligned on-disk
185 */
186 if (first_block & (blocks_per_page - 1)) {
187 probe_block++;
188 goto reprobe;
189 }
190
191 for (block_in_page = 1; block_in_page < blocks_per_page;
192 block_in_page++) {
193 sector_t block;
194
195 block = bmap(inode, probe_block + block_in_page);
196 if (block == 0)
197 goto bad_bmap;
198 if (block != first_block + block_in_page) {
199 /* Discontiguity */
200 probe_block++;
201 goto reprobe;
202 }
203 }
204
205 first_block >>= (PAGE_SHIFT - blkbits);
206 if (page_no) { /* exclude the header page */
207 if (first_block < lowest_block)
208 lowest_block = first_block;
209 if (first_block > highest_block)
210 highest_block = first_block;
211 }
212
213 /*
214 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
215 */
216 ret = add_swap_extent(sis, page_no, 1, first_block);
217 if (ret < 0)
218 goto out;
219 nr_extents += ret;
220 page_no++;
221 probe_block += blocks_per_page;
222reprobe:
223 continue;
224 }
225 ret = nr_extents;
226 *span = 1 + highest_block - lowest_block;
227 if (page_no == 0)
228 page_no = 1; /* force Empty message */
229 sis->max = page_no;
230 sis->pages = page_no - 1;
231 sis->highest_bit = page_no - 1;
232out:
233 return ret;
234bad_bmap:
235 pr_err("swapon: swapfile has holes\n");
236 ret = -EINVAL;
237 goto out;
238}
239
240/*
241 * We may have stale swap cache pages in memory: notice
242 * them here and get rid of the unnecessary final write.
243 */
244int swap_writepage(struct page *page, struct writeback_control *wbc)
245{
246 int ret = 0;
247
248 if (try_to_free_swap(page)) {
249 unlock_page(page);
250 goto out;
251 }
252 if (frontswap_store(page) == 0) {
253 set_page_writeback(page);
254 unlock_page(page);
255 end_page_writeback(page);
256 goto out;
257 }
258 ret = __swap_writepage(page, wbc, end_swap_bio_write);
259out:
260 return ret;
261}
262
263static sector_t swap_page_sector(struct page *page)
264{
265 return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9);
266}
267
268static inline void count_swpout_vm_event(struct page *page)
269{
270#ifdef CONFIG_TRANSPARENT_HUGEPAGE
271 if (unlikely(PageTransHuge(page)))
272 count_vm_event(THP_SWPOUT);
273#endif
274 count_vm_events(PSWPOUT, hpage_nr_pages(page));
275}
276
277int __swap_writepage(struct page *page, struct writeback_control *wbc,
278 bio_end_io_t end_write_func)
279{
280 struct bio *bio;
281 int ret;
282 struct swap_info_struct *sis = page_swap_info(page);
283
284 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
285 if (sis->flags & SWP_FS) {
286 struct kiocb kiocb;
287 struct file *swap_file = sis->swap_file;
288 struct address_space *mapping = swap_file->f_mapping;
289 struct bio_vec bv = {
290 .bv_page = page,
291 .bv_len = PAGE_SIZE,
292 .bv_offset = 0
293 };
294 struct iov_iter from;
295
296 iov_iter_bvec(&from, WRITE, &bv, 1, PAGE_SIZE);
297 init_sync_kiocb(&kiocb, swap_file);
298 kiocb.ki_pos = page_file_offset(page);
299
300 set_page_writeback(page);
301 unlock_page(page);
302 ret = mapping->a_ops->direct_IO(&kiocb, &from);
303 if (ret == PAGE_SIZE) {
304 count_vm_event(PSWPOUT);
305 ret = 0;
306 } else {
307 /*
308 * In the case of swap-over-nfs, this can be a
309 * temporary failure if the system has limited
310 * memory for allocating transmit buffers.
311 * Mark the page dirty and avoid
312 * rotate_reclaimable_page but rate-limit the
313 * messages but do not flag PageError like
314 * the normal direct-to-bio case as it could
315 * be temporary.
316 */
317 set_page_dirty(page);
318 ClearPageReclaim(page);
319 pr_err_ratelimited("Write error on dio swapfile (%llu)\n",
320 page_file_offset(page));
321 }
322 end_page_writeback(page);
323 return ret;
324 }
325
326 ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
327 if (!ret) {
328 count_swpout_vm_event(page);
329 return 0;
330 }
331
332 ret = 0;
333 bio = get_swap_bio(GFP_NOIO, page, end_write_func);
334 if (bio == NULL) {
335 set_page_dirty(page);
336 unlock_page(page);
337 ret = -ENOMEM;
338 goto out;
339 }
340 bio->bi_opf = REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc);
341 bio_associate_blkg_from_page(bio, page);
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_FS) {
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 bio_set_op_attrs(bio, REQ_OP_READ, 0);
401 if (synchronous) {
402 bio->bi_opf |= REQ_HIPRI;
403 get_task_struct(current);
404 bio->bi_private = current;
405 }
406 count_vm_event(PSWPIN);
407 bio_get(bio);
408 qc = submit_bio(bio);
409 while (synchronous) {
410 set_current_state(TASK_UNINTERRUPTIBLE);
411 if (!READ_ONCE(bio->bi_private))
412 break;
413
414 if (!blk_poll(disk->queue, qc, true))
415 io_schedule();
416 }
417 __set_current_state(TASK_RUNNING);
418 bio_put(bio);
419
420out:
421 return ret;
422}
423
424int swap_set_page_dirty(struct page *page)
425{
426 struct swap_info_struct *sis = page_swap_info(page);
427
428 if (sis->flags & SWP_FS) {
429 struct address_space *mapping = sis->swap_file->f_mapping;
430
431 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
432 return mapping->a_ops->set_page_dirty(page);
433 } else {
434 return __set_page_dirty_no_writeback(page);
435 }
436}
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#include <linux/delayacct.h>
29#include "swap.h"
30
31static void end_swap_bio_write(struct bio *bio)
32{
33 struct page *page = bio_first_page_all(bio);
34
35 if (bio->bi_status) {
36 SetPageError(page);
37 /*
38 * We failed to write the page out to swap-space.
39 * Re-dirty the page in order to avoid it being reclaimed.
40 * Also print a dire warning that things will go BAD (tm)
41 * very quickly.
42 *
43 * Also clear PG_reclaim to avoid folio_rotate_reclaimable()
44 */
45 set_page_dirty(page);
46 pr_alert_ratelimited("Write-error on swap-device (%u:%u:%llu)\n",
47 MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
48 (unsigned long long)bio->bi_iter.bi_sector);
49 ClearPageReclaim(page);
50 }
51 end_page_writeback(page);
52 bio_put(bio);
53}
54
55static void end_swap_bio_read(struct bio *bio)
56{
57 struct page *page = bio_first_page_all(bio);
58 struct task_struct *waiter = bio->bi_private;
59
60 if (bio->bi_status) {
61 SetPageError(page);
62 ClearPageUptodate(page);
63 pr_alert_ratelimited("Read-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 goto out;
67 }
68
69 SetPageUptodate(page);
70out:
71 unlock_page(page);
72 WRITE_ONCE(bio->bi_private, NULL);
73 bio_put(bio);
74 if (waiter) {
75 blk_wake_io_task(waiter);
76 put_task_struct(waiter);
77 }
78}
79
80int generic_swapfile_activate(struct swap_info_struct *sis,
81 struct file *swap_file,
82 sector_t *span)
83{
84 struct address_space *mapping = swap_file->f_mapping;
85 struct inode *inode = mapping->host;
86 unsigned blocks_per_page;
87 unsigned long page_no;
88 unsigned blkbits;
89 sector_t probe_block;
90 sector_t last_block;
91 sector_t lowest_block = -1;
92 sector_t highest_block = 0;
93 int nr_extents = 0;
94 int ret;
95
96 blkbits = inode->i_blkbits;
97 blocks_per_page = PAGE_SIZE >> blkbits;
98
99 /*
100 * Map all the blocks into the extent tree. This code doesn't try
101 * to be very smart.
102 */
103 probe_block = 0;
104 page_no = 0;
105 last_block = i_size_read(inode) >> blkbits;
106 while ((probe_block + blocks_per_page) <= last_block &&
107 page_no < sis->max) {
108 unsigned block_in_page;
109 sector_t first_block;
110
111 cond_resched();
112
113 first_block = probe_block;
114 ret = bmap(inode, &first_block);
115 if (ret || !first_block)
116 goto bad_bmap;
117
118 /*
119 * It must be PAGE_SIZE aligned on-disk
120 */
121 if (first_block & (blocks_per_page - 1)) {
122 probe_block++;
123 goto reprobe;
124 }
125
126 for (block_in_page = 1; block_in_page < blocks_per_page;
127 block_in_page++) {
128 sector_t block;
129
130 block = probe_block + block_in_page;
131 ret = bmap(inode, &block);
132 if (ret || !block)
133 goto bad_bmap;
134
135 if (block != first_block + block_in_page) {
136 /* Discontiguity */
137 probe_block++;
138 goto reprobe;
139 }
140 }
141
142 first_block >>= (PAGE_SHIFT - blkbits);
143 if (page_no) { /* exclude the header page */
144 if (first_block < lowest_block)
145 lowest_block = first_block;
146 if (first_block > highest_block)
147 highest_block = first_block;
148 }
149
150 /*
151 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
152 */
153 ret = add_swap_extent(sis, page_no, 1, first_block);
154 if (ret < 0)
155 goto out;
156 nr_extents += ret;
157 page_no++;
158 probe_block += blocks_per_page;
159reprobe:
160 continue;
161 }
162 ret = nr_extents;
163 *span = 1 + highest_block - lowest_block;
164 if (page_no == 0)
165 page_no = 1; /* force Empty message */
166 sis->max = page_no;
167 sis->pages = page_no - 1;
168 sis->highest_bit = page_no - 1;
169out:
170 return ret;
171bad_bmap:
172 pr_err("swapon: swapfile has holes\n");
173 ret = -EINVAL;
174 goto out;
175}
176
177/*
178 * We may have stale swap cache pages in memory: notice
179 * them here and get rid of the unnecessary final write.
180 */
181int swap_writepage(struct page *page, struct writeback_control *wbc)
182{
183 struct folio *folio = page_folio(page);
184 int ret = 0;
185
186 if (folio_free_swap(folio)) {
187 folio_unlock(folio);
188 goto out;
189 }
190 /*
191 * Arch code may have to preserve more data than just the page
192 * contents, e.g. memory tags.
193 */
194 ret = arch_prepare_to_swap(&folio->page);
195 if (ret) {
196 folio_mark_dirty(folio);
197 folio_unlock(folio);
198 goto out;
199 }
200 if (frontswap_store(&folio->page) == 0) {
201 folio_start_writeback(folio);
202 folio_unlock(folio);
203 folio_end_writeback(folio);
204 goto out;
205 }
206 ret = __swap_writepage(&folio->page, wbc);
207out:
208 return ret;
209}
210
211static inline void count_swpout_vm_event(struct page *page)
212{
213#ifdef CONFIG_TRANSPARENT_HUGEPAGE
214 if (unlikely(PageTransHuge(page)))
215 count_vm_event(THP_SWPOUT);
216#endif
217 count_vm_events(PSWPOUT, thp_nr_pages(page));
218}
219
220#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
221static void bio_associate_blkg_from_page(struct bio *bio, struct page *page)
222{
223 struct cgroup_subsys_state *css;
224 struct mem_cgroup *memcg;
225
226 memcg = page_memcg(page);
227 if (!memcg)
228 return;
229
230 rcu_read_lock();
231 css = cgroup_e_css(memcg->css.cgroup, &io_cgrp_subsys);
232 bio_associate_blkg_from_css(bio, css);
233 rcu_read_unlock();
234}
235#else
236#define bio_associate_blkg_from_page(bio, page) do { } while (0)
237#endif /* CONFIG_MEMCG && CONFIG_BLK_CGROUP */
238
239struct swap_iocb {
240 struct kiocb iocb;
241 struct bio_vec bvec[SWAP_CLUSTER_MAX];
242 int pages;
243 int len;
244};
245static mempool_t *sio_pool;
246
247int sio_pool_init(void)
248{
249 if (!sio_pool) {
250 mempool_t *pool = mempool_create_kmalloc_pool(
251 SWAP_CLUSTER_MAX, sizeof(struct swap_iocb));
252 if (cmpxchg(&sio_pool, NULL, pool))
253 mempool_destroy(pool);
254 }
255 if (!sio_pool)
256 return -ENOMEM;
257 return 0;
258}
259
260static void sio_write_complete(struct kiocb *iocb, long ret)
261{
262 struct swap_iocb *sio = container_of(iocb, struct swap_iocb, iocb);
263 struct page *page = sio->bvec[0].bv_page;
264 int p;
265
266 if (ret != sio->len) {
267 /*
268 * In the case of swap-over-nfs, this can be a
269 * temporary failure if the system has limited
270 * memory for allocating transmit buffers.
271 * Mark the page dirty and avoid
272 * folio_rotate_reclaimable but rate-limit the
273 * messages but do not flag PageError like
274 * the normal direct-to-bio case as it could
275 * be temporary.
276 */
277 pr_err_ratelimited("Write error %ld on dio swapfile (%llu)\n",
278 ret, page_file_offset(page));
279 for (p = 0; p < sio->pages; p++) {
280 page = sio->bvec[p].bv_page;
281 set_page_dirty(page);
282 ClearPageReclaim(page);
283 }
284 } else {
285 for (p = 0; p < sio->pages; p++)
286 count_swpout_vm_event(sio->bvec[p].bv_page);
287 }
288
289 for (p = 0; p < sio->pages; p++)
290 end_page_writeback(sio->bvec[p].bv_page);
291
292 mempool_free(sio, sio_pool);
293}
294
295static int swap_writepage_fs(struct page *page, struct writeback_control *wbc)
296{
297 struct swap_iocb *sio = NULL;
298 struct swap_info_struct *sis = page_swap_info(page);
299 struct file *swap_file = sis->swap_file;
300 loff_t pos = page_file_offset(page);
301
302 set_page_writeback(page);
303 unlock_page(page);
304 if (wbc->swap_plug)
305 sio = *wbc->swap_plug;
306 if (sio) {
307 if (sio->iocb.ki_filp != swap_file ||
308 sio->iocb.ki_pos + sio->len != pos) {
309 swap_write_unplug(sio);
310 sio = NULL;
311 }
312 }
313 if (!sio) {
314 sio = mempool_alloc(sio_pool, GFP_NOIO);
315 init_sync_kiocb(&sio->iocb, swap_file);
316 sio->iocb.ki_complete = sio_write_complete;
317 sio->iocb.ki_pos = pos;
318 sio->pages = 0;
319 sio->len = 0;
320 }
321 sio->bvec[sio->pages].bv_page = page;
322 sio->bvec[sio->pages].bv_len = thp_size(page);
323 sio->bvec[sio->pages].bv_offset = 0;
324 sio->len += thp_size(page);
325 sio->pages += 1;
326 if (sio->pages == ARRAY_SIZE(sio->bvec) || !wbc->swap_plug) {
327 swap_write_unplug(sio);
328 sio = NULL;
329 }
330 if (wbc->swap_plug)
331 *wbc->swap_plug = sio;
332
333 return 0;
334}
335
336int __swap_writepage(struct page *page, struct writeback_control *wbc)
337{
338 struct bio *bio;
339 int ret;
340 struct swap_info_struct *sis = page_swap_info(page);
341
342 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
343 /*
344 * ->flags can be updated non-atomicially (scan_swap_map_slots),
345 * but that will never affect SWP_FS_OPS, so the data_race
346 * is safe.
347 */
348 if (data_race(sis->flags & SWP_FS_OPS))
349 return swap_writepage_fs(page, wbc);
350
351 ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
352 if (!ret) {
353 count_swpout_vm_event(page);
354 return 0;
355 }
356
357 bio = bio_alloc(sis->bdev, 1,
358 REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc),
359 GFP_NOIO);
360 bio->bi_iter.bi_sector = swap_page_sector(page);
361 bio->bi_end_io = end_swap_bio_write;
362 bio_add_page(bio, page, thp_size(page), 0);
363
364 bio_associate_blkg_from_page(bio, page);
365 count_swpout_vm_event(page);
366 set_page_writeback(page);
367 unlock_page(page);
368 submit_bio(bio);
369
370 return 0;
371}
372
373void swap_write_unplug(struct swap_iocb *sio)
374{
375 struct iov_iter from;
376 struct address_space *mapping = sio->iocb.ki_filp->f_mapping;
377 int ret;
378
379 iov_iter_bvec(&from, ITER_SOURCE, sio->bvec, sio->pages, sio->len);
380 ret = mapping->a_ops->swap_rw(&sio->iocb, &from);
381 if (ret != -EIOCBQUEUED)
382 sio_write_complete(&sio->iocb, ret);
383}
384
385static void sio_read_complete(struct kiocb *iocb, long ret)
386{
387 struct swap_iocb *sio = container_of(iocb, struct swap_iocb, iocb);
388 int p;
389
390 if (ret == sio->len) {
391 for (p = 0; p < sio->pages; p++) {
392 struct page *page = sio->bvec[p].bv_page;
393
394 SetPageUptodate(page);
395 unlock_page(page);
396 }
397 count_vm_events(PSWPIN, sio->pages);
398 } else {
399 for (p = 0; p < sio->pages; p++) {
400 struct page *page = sio->bvec[p].bv_page;
401
402 SetPageError(page);
403 ClearPageUptodate(page);
404 unlock_page(page);
405 }
406 pr_alert_ratelimited("Read-error on swap-device\n");
407 }
408 mempool_free(sio, sio_pool);
409}
410
411static void swap_readpage_fs(struct page *page,
412 struct swap_iocb **plug)
413{
414 struct swap_info_struct *sis = page_swap_info(page);
415 struct swap_iocb *sio = NULL;
416 loff_t pos = page_file_offset(page);
417
418 if (plug)
419 sio = *plug;
420 if (sio) {
421 if (sio->iocb.ki_filp != sis->swap_file ||
422 sio->iocb.ki_pos + sio->len != pos) {
423 swap_read_unplug(sio);
424 sio = NULL;
425 }
426 }
427 if (!sio) {
428 sio = mempool_alloc(sio_pool, GFP_KERNEL);
429 init_sync_kiocb(&sio->iocb, sis->swap_file);
430 sio->iocb.ki_pos = pos;
431 sio->iocb.ki_complete = sio_read_complete;
432 sio->pages = 0;
433 sio->len = 0;
434 }
435 sio->bvec[sio->pages].bv_page = page;
436 sio->bvec[sio->pages].bv_len = thp_size(page);
437 sio->bvec[sio->pages].bv_offset = 0;
438 sio->len += thp_size(page);
439 sio->pages += 1;
440 if (sio->pages == ARRAY_SIZE(sio->bvec) || !plug) {
441 swap_read_unplug(sio);
442 sio = NULL;
443 }
444 if (plug)
445 *plug = sio;
446}
447
448int swap_readpage(struct page *page, bool synchronous,
449 struct swap_iocb **plug)
450{
451 struct bio *bio;
452 int ret = 0;
453 struct swap_info_struct *sis = page_swap_info(page);
454 bool workingset = PageWorkingset(page);
455 unsigned long pflags;
456 bool in_thrashing;
457
458 VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
459 VM_BUG_ON_PAGE(!PageLocked(page), page);
460 VM_BUG_ON_PAGE(PageUptodate(page), page);
461
462 /*
463 * Count submission time as memory stall and delay. When the device
464 * is congested, or the submitting cgroup IO-throttled, submission
465 * can be a significant part of overall IO time.
466 */
467 if (workingset) {
468 delayacct_thrashing_start(&in_thrashing);
469 psi_memstall_enter(&pflags);
470 }
471 delayacct_swapin_start();
472
473 if (frontswap_load(page) == 0) {
474 SetPageUptodate(page);
475 unlock_page(page);
476 goto out;
477 }
478
479 if (data_race(sis->flags & SWP_FS_OPS)) {
480 swap_readpage_fs(page, plug);
481 goto out;
482 }
483
484 if (sis->flags & SWP_SYNCHRONOUS_IO) {
485 ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
486 if (!ret) {
487 count_vm_event(PSWPIN);
488 goto out;
489 }
490 }
491
492 ret = 0;
493 bio = bio_alloc(sis->bdev, 1, REQ_OP_READ, GFP_KERNEL);
494 bio->bi_iter.bi_sector = swap_page_sector(page);
495 bio->bi_end_io = end_swap_bio_read;
496 bio_add_page(bio, page, thp_size(page), 0);
497 /*
498 * Keep this task valid during swap readpage because the oom killer may
499 * attempt to access it in the page fault retry time check.
500 */
501 if (synchronous) {
502 get_task_struct(current);
503 bio->bi_private = current;
504 }
505 count_vm_event(PSWPIN);
506 bio_get(bio);
507 submit_bio(bio);
508 while (synchronous) {
509 set_current_state(TASK_UNINTERRUPTIBLE);
510 if (!READ_ONCE(bio->bi_private))
511 break;
512
513 blk_io_schedule();
514 }
515 __set_current_state(TASK_RUNNING);
516 bio_put(bio);
517
518out:
519 if (workingset) {
520 delayacct_thrashing_end(&in_thrashing);
521 psi_memstall_leave(&pflags);
522 }
523 delayacct_swapin_end();
524 return ret;
525}
526
527void __swap_read_unplug(struct swap_iocb *sio)
528{
529 struct iov_iter from;
530 struct address_space *mapping = sio->iocb.ki_filp->f_mapping;
531 int ret;
532
533 iov_iter_bvec(&from, ITER_DEST, sio->bvec, sio->pages, sio->len);
534 ret = mapping->a_ops->swap_rw(&sio->iocb, &from);
535 if (ret != -EIOCBQUEUED)
536 sio_read_complete(&sio->iocb, ret);
537}