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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/writeback.h>
22#include <linux/blkdev.h>
23#include <linux/psi.h>
24#include <linux/uio.h>
25#include <linux/sched/task.h>
26#include <linux/delayacct.h>
27#include <linux/zswap.h>
28#include "swap.h"
29
30static void __end_swap_bio_write(struct bio *bio)
31{
32 struct folio *folio = bio_first_folio_all(bio);
33
34 if (bio->bi_status) {
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 folio_rotate_reclaimable()
42 */
43 folio_mark_dirty(folio);
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 folio_clear_reclaim(folio);
48 }
49 folio_end_writeback(folio);
50}
51
52static void end_swap_bio_write(struct bio *bio)
53{
54 __end_swap_bio_write(bio);
55 bio_put(bio);
56}
57
58static void __end_swap_bio_read(struct bio *bio)
59{
60 struct folio *folio = bio_first_folio_all(bio);
61
62 if (bio->bi_status) {
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 } else {
67 folio_mark_uptodate(folio);
68 }
69 folio_unlock(folio);
70}
71
72static void end_swap_bio_read(struct bio *bio)
73{
74 __end_swap_bio_read(bio);
75 bio_put(bio);
76}
77
78int generic_swapfile_activate(struct swap_info_struct *sis,
79 struct file *swap_file,
80 sector_t *span)
81{
82 struct address_space *mapping = swap_file->f_mapping;
83 struct inode *inode = mapping->host;
84 unsigned blocks_per_page;
85 unsigned long page_no;
86 unsigned blkbits;
87 sector_t probe_block;
88 sector_t last_block;
89 sector_t lowest_block = -1;
90 sector_t highest_block = 0;
91 int nr_extents = 0;
92 int ret;
93
94 blkbits = inode->i_blkbits;
95 blocks_per_page = PAGE_SIZE >> blkbits;
96
97 /*
98 * Map all the blocks into the extent tree. This code doesn't try
99 * to be very smart.
100 */
101 probe_block = 0;
102 page_no = 0;
103 last_block = i_size_read(inode) >> blkbits;
104 while ((probe_block + blocks_per_page) <= last_block &&
105 page_no < sis->max) {
106 unsigned block_in_page;
107 sector_t first_block;
108
109 cond_resched();
110
111 first_block = probe_block;
112 ret = bmap(inode, &first_block);
113 if (ret || !first_block)
114 goto bad_bmap;
115
116 /*
117 * It must be PAGE_SIZE aligned on-disk
118 */
119 if (first_block & (blocks_per_page - 1)) {
120 probe_block++;
121 goto reprobe;
122 }
123
124 for (block_in_page = 1; block_in_page < blocks_per_page;
125 block_in_page++) {
126 sector_t block;
127
128 block = probe_block + block_in_page;
129 ret = bmap(inode, &block);
130 if (ret || !block)
131 goto bad_bmap;
132
133 if (block != first_block + block_in_page) {
134 /* Discontiguity */
135 probe_block++;
136 goto reprobe;
137 }
138 }
139
140 first_block >>= (PAGE_SHIFT - blkbits);
141 if (page_no) { /* exclude the header page */
142 if (first_block < lowest_block)
143 lowest_block = first_block;
144 if (first_block > highest_block)
145 highest_block = first_block;
146 }
147
148 /*
149 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
150 */
151 ret = add_swap_extent(sis, page_no, 1, first_block);
152 if (ret < 0)
153 goto out;
154 nr_extents += ret;
155 page_no++;
156 probe_block += blocks_per_page;
157reprobe:
158 continue;
159 }
160 ret = nr_extents;
161 *span = 1 + highest_block - lowest_block;
162 if (page_no == 0)
163 page_no = 1; /* force Empty message */
164 sis->max = page_no;
165 sis->pages = page_no - 1;
166 sis->highest_bit = page_no - 1;
167out:
168 return ret;
169bad_bmap:
170 pr_err("swapon: swapfile has holes\n");
171 ret = -EINVAL;
172 goto out;
173}
174
175/*
176 * We may have stale swap cache pages in memory: notice
177 * them here and get rid of the unnecessary final write.
178 */
179int swap_writepage(struct page *page, struct writeback_control *wbc)
180{
181 struct folio *folio = page_folio(page);
182 int ret;
183
184 if (folio_free_swap(folio)) {
185 folio_unlock(folio);
186 return 0;
187 }
188 /*
189 * Arch code may have to preserve more data than just the page
190 * contents, e.g. memory tags.
191 */
192 ret = arch_prepare_to_swap(&folio->page);
193 if (ret) {
194 folio_mark_dirty(folio);
195 folio_unlock(folio);
196 return ret;
197 }
198 if (zswap_store(folio)) {
199 folio_start_writeback(folio);
200 folio_unlock(folio);
201 folio_end_writeback(folio);
202 return 0;
203 }
204 if (!mem_cgroup_zswap_writeback_enabled(folio_memcg(folio))) {
205 folio_mark_dirty(folio);
206 return AOP_WRITEPAGE_ACTIVATE;
207 }
208
209 __swap_writepage(folio, wbc);
210 return 0;
211}
212
213static inline void count_swpout_vm_event(struct folio *folio)
214{
215#ifdef CONFIG_TRANSPARENT_HUGEPAGE
216 if (unlikely(folio_test_pmd_mappable(folio))) {
217 count_memcg_folio_events(folio, THP_SWPOUT, 1);
218 count_vm_event(THP_SWPOUT);
219 }
220#endif
221 count_vm_events(PSWPOUT, folio_nr_pages(folio));
222}
223
224#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
225static void bio_associate_blkg_from_page(struct bio *bio, struct folio *folio)
226{
227 struct cgroup_subsys_state *css;
228 struct mem_cgroup *memcg;
229
230 memcg = folio_memcg(folio);
231 if (!memcg)
232 return;
233
234 rcu_read_lock();
235 css = cgroup_e_css(memcg->css.cgroup, &io_cgrp_subsys);
236 bio_associate_blkg_from_css(bio, css);
237 rcu_read_unlock();
238}
239#else
240#define bio_associate_blkg_from_page(bio, folio) do { } while (0)
241#endif /* CONFIG_MEMCG && CONFIG_BLK_CGROUP */
242
243struct swap_iocb {
244 struct kiocb iocb;
245 struct bio_vec bvec[SWAP_CLUSTER_MAX];
246 int pages;
247 int len;
248};
249static mempool_t *sio_pool;
250
251int sio_pool_init(void)
252{
253 if (!sio_pool) {
254 mempool_t *pool = mempool_create_kmalloc_pool(
255 SWAP_CLUSTER_MAX, sizeof(struct swap_iocb));
256 if (cmpxchg(&sio_pool, NULL, pool))
257 mempool_destroy(pool);
258 }
259 if (!sio_pool)
260 return -ENOMEM;
261 return 0;
262}
263
264static void sio_write_complete(struct kiocb *iocb, long ret)
265{
266 struct swap_iocb *sio = container_of(iocb, struct swap_iocb, iocb);
267 struct page *page = sio->bvec[0].bv_page;
268 int p;
269
270 if (ret != sio->len) {
271 /*
272 * In the case of swap-over-nfs, this can be a
273 * temporary failure if the system has limited
274 * memory for allocating transmit buffers.
275 * Mark the page dirty and avoid
276 * folio_rotate_reclaimable but rate-limit the
277 * messages but do not flag PageError like
278 * the normal direct-to-bio case as it could
279 * be temporary.
280 */
281 pr_err_ratelimited("Write error %ld on dio swapfile (%llu)\n",
282 ret, page_file_offset(page));
283 for (p = 0; p < sio->pages; p++) {
284 page = sio->bvec[p].bv_page;
285 set_page_dirty(page);
286 ClearPageReclaim(page);
287 }
288 }
289
290 for (p = 0; p < sio->pages; p++)
291 end_page_writeback(sio->bvec[p].bv_page);
292
293 mempool_free(sio, sio_pool);
294}
295
296static void swap_writepage_fs(struct folio *folio, struct writeback_control *wbc)
297{
298 struct swap_iocb *sio = NULL;
299 struct swap_info_struct *sis = swp_swap_info(folio->swap);
300 struct file *swap_file = sis->swap_file;
301 loff_t pos = folio_file_pos(folio);
302
303 count_swpout_vm_event(folio);
304 folio_start_writeback(folio);
305 folio_unlock(folio);
306 if (wbc->swap_plug)
307 sio = *wbc->swap_plug;
308 if (sio) {
309 if (sio->iocb.ki_filp != swap_file ||
310 sio->iocb.ki_pos + sio->len != pos) {
311 swap_write_unplug(sio);
312 sio = NULL;
313 }
314 }
315 if (!sio) {
316 sio = mempool_alloc(sio_pool, GFP_NOIO);
317 init_sync_kiocb(&sio->iocb, swap_file);
318 sio->iocb.ki_complete = sio_write_complete;
319 sio->iocb.ki_pos = pos;
320 sio->pages = 0;
321 sio->len = 0;
322 }
323 bvec_set_folio(&sio->bvec[sio->pages], folio, folio_size(folio), 0);
324 sio->len += folio_size(folio);
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
334static void swap_writepage_bdev_sync(struct folio *folio,
335 struct writeback_control *wbc, struct swap_info_struct *sis)
336{
337 struct bio_vec bv;
338 struct bio bio;
339
340 bio_init(&bio, sis->bdev, &bv, 1,
341 REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc));
342 bio.bi_iter.bi_sector = swap_folio_sector(folio);
343 bio_add_folio_nofail(&bio, folio, folio_size(folio), 0);
344
345 bio_associate_blkg_from_page(&bio, folio);
346 count_swpout_vm_event(folio);
347
348 folio_start_writeback(folio);
349 folio_unlock(folio);
350
351 submit_bio_wait(&bio);
352 __end_swap_bio_write(&bio);
353}
354
355static void swap_writepage_bdev_async(struct folio *folio,
356 struct writeback_control *wbc, struct swap_info_struct *sis)
357{
358 struct bio *bio;
359
360 bio = bio_alloc(sis->bdev, 1,
361 REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc),
362 GFP_NOIO);
363 bio->bi_iter.bi_sector = swap_folio_sector(folio);
364 bio->bi_end_io = end_swap_bio_write;
365 bio_add_folio_nofail(bio, folio, folio_size(folio), 0);
366
367 bio_associate_blkg_from_page(bio, folio);
368 count_swpout_vm_event(folio);
369 folio_start_writeback(folio);
370 folio_unlock(folio);
371 submit_bio(bio);
372}
373
374void __swap_writepage(struct folio *folio, struct writeback_control *wbc)
375{
376 struct swap_info_struct *sis = swp_swap_info(folio->swap);
377
378 VM_BUG_ON_FOLIO(!folio_test_swapcache(folio), folio);
379 /*
380 * ->flags can be updated non-atomicially (scan_swap_map_slots),
381 * but that will never affect SWP_FS_OPS, so the data_race
382 * is safe.
383 */
384 if (data_race(sis->flags & SWP_FS_OPS))
385 swap_writepage_fs(folio, wbc);
386 else if (sis->flags & SWP_SYNCHRONOUS_IO)
387 swap_writepage_bdev_sync(folio, wbc, sis);
388 else
389 swap_writepage_bdev_async(folio, wbc, sis);
390}
391
392void swap_write_unplug(struct swap_iocb *sio)
393{
394 struct iov_iter from;
395 struct address_space *mapping = sio->iocb.ki_filp->f_mapping;
396 int ret;
397
398 iov_iter_bvec(&from, ITER_SOURCE, sio->bvec, sio->pages, sio->len);
399 ret = mapping->a_ops->swap_rw(&sio->iocb, &from);
400 if (ret != -EIOCBQUEUED)
401 sio_write_complete(&sio->iocb, ret);
402}
403
404static void sio_read_complete(struct kiocb *iocb, long ret)
405{
406 struct swap_iocb *sio = container_of(iocb, struct swap_iocb, iocb);
407 int p;
408
409 if (ret == sio->len) {
410 for (p = 0; p < sio->pages; p++) {
411 struct folio *folio = page_folio(sio->bvec[p].bv_page);
412
413 folio_mark_uptodate(folio);
414 folio_unlock(folio);
415 }
416 count_vm_events(PSWPIN, sio->pages);
417 } else {
418 for (p = 0; p < sio->pages; p++) {
419 struct folio *folio = page_folio(sio->bvec[p].bv_page);
420
421 folio_unlock(folio);
422 }
423 pr_alert_ratelimited("Read-error on swap-device\n");
424 }
425 mempool_free(sio, sio_pool);
426}
427
428static void swap_read_folio_fs(struct folio *folio, struct swap_iocb **plug)
429{
430 struct swap_info_struct *sis = swp_swap_info(folio->swap);
431 struct swap_iocb *sio = NULL;
432 loff_t pos = folio_file_pos(folio);
433
434 if (plug)
435 sio = *plug;
436 if (sio) {
437 if (sio->iocb.ki_filp != sis->swap_file ||
438 sio->iocb.ki_pos + sio->len != pos) {
439 swap_read_unplug(sio);
440 sio = NULL;
441 }
442 }
443 if (!sio) {
444 sio = mempool_alloc(sio_pool, GFP_KERNEL);
445 init_sync_kiocb(&sio->iocb, sis->swap_file);
446 sio->iocb.ki_pos = pos;
447 sio->iocb.ki_complete = sio_read_complete;
448 sio->pages = 0;
449 sio->len = 0;
450 }
451 bvec_set_folio(&sio->bvec[sio->pages], folio, folio_size(folio), 0);
452 sio->len += folio_size(folio);
453 sio->pages += 1;
454 if (sio->pages == ARRAY_SIZE(sio->bvec) || !plug) {
455 swap_read_unplug(sio);
456 sio = NULL;
457 }
458 if (plug)
459 *plug = sio;
460}
461
462static void swap_read_folio_bdev_sync(struct folio *folio,
463 struct swap_info_struct *sis)
464{
465 struct bio_vec bv;
466 struct bio bio;
467
468 bio_init(&bio, sis->bdev, &bv, 1, REQ_OP_READ);
469 bio.bi_iter.bi_sector = swap_folio_sector(folio);
470 bio_add_folio_nofail(&bio, folio, folio_size(folio), 0);
471 /*
472 * Keep this task valid during swap readpage because the oom killer may
473 * attempt to access it in the page fault retry time check.
474 */
475 get_task_struct(current);
476 count_vm_event(PSWPIN);
477 submit_bio_wait(&bio);
478 __end_swap_bio_read(&bio);
479 put_task_struct(current);
480}
481
482static void swap_read_folio_bdev_async(struct folio *folio,
483 struct swap_info_struct *sis)
484{
485 struct bio *bio;
486
487 bio = bio_alloc(sis->bdev, 1, REQ_OP_READ, GFP_KERNEL);
488 bio->bi_iter.bi_sector = swap_folio_sector(folio);
489 bio->bi_end_io = end_swap_bio_read;
490 bio_add_folio_nofail(bio, folio, folio_size(folio), 0);
491 count_vm_event(PSWPIN);
492 submit_bio(bio);
493}
494
495void swap_read_folio(struct folio *folio, bool synchronous,
496 struct swap_iocb **plug)
497{
498 struct swap_info_struct *sis = swp_swap_info(folio->swap);
499 bool workingset = folio_test_workingset(folio);
500 unsigned long pflags;
501 bool in_thrashing;
502
503 VM_BUG_ON_FOLIO(!folio_test_swapcache(folio) && !synchronous, folio);
504 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
505 VM_BUG_ON_FOLIO(folio_test_uptodate(folio), folio);
506
507 /*
508 * Count submission time as memory stall and delay. When the device
509 * is congested, or the submitting cgroup IO-throttled, submission
510 * can be a significant part of overall IO time.
511 */
512 if (workingset) {
513 delayacct_thrashing_start(&in_thrashing);
514 psi_memstall_enter(&pflags);
515 }
516 delayacct_swapin_start();
517
518 if (zswap_load(folio)) {
519 folio_mark_uptodate(folio);
520 folio_unlock(folio);
521 } else if (data_race(sis->flags & SWP_FS_OPS)) {
522 swap_read_folio_fs(folio, plug);
523 } else if (synchronous || (sis->flags & SWP_SYNCHRONOUS_IO)) {
524 swap_read_folio_bdev_sync(folio, sis);
525 } else {
526 swap_read_folio_bdev_async(folio, sis);
527 }
528
529 if (workingset) {
530 delayacct_thrashing_end(&in_thrashing);
531 psi_memstall_leave(&pflags);
532 }
533 delayacct_swapin_end();
534}
535
536void __swap_read_unplug(struct swap_iocb *sio)
537{
538 struct iov_iter from;
539 struct address_space *mapping = sio->iocb.ki_filp->f_mapping;
540 int ret;
541
542 iov_iter_bvec(&from, ITER_DEST, sio->bvec, sio->pages, sio->len);
543 ret = mapping->a_ops->swap_rw(&sio->iocb, &from);
544 if (ret != -EIOCBQUEUED)
545 sio_read_complete(&sio->iocb, ret);
546}
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}