Commit | Line | Data |
---|---|---|
b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
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> | |
5a0e3ad6 | 16 | #include <linux/gfp.h> |
1da177e4 LT |
17 | #include <linux/pagemap.h> |
18 | #include <linux/swap.h> | |
19 | #include <linux/bio.h> | |
20 | #include <linux/swapops.h> | |
62c230bc | 21 | #include <linux/buffer_head.h> |
1da177e4 | 22 | #include <linux/writeback.h> |
38b5faf4 | 23 | #include <linux/frontswap.h> |
b430e9d1 | 24 | #include <linux/blkdev.h> |
93779069 | 25 | #include <linux/psi.h> |
e2e40f2c | 26 | #include <linux/uio.h> |
b0ba2d0f | 27 | #include <linux/sched/task.h> |
1da177e4 | 28 | |
4246a0b6 | 29 | void end_swap_bio_write(struct bio *bio) |
1da177e4 | 30 | { |
263663cd | 31 | struct page *page = bio_first_page_all(bio); |
1da177e4 | 32 | |
4e4cbee9 | 33 | if (bio->bi_status) { |
1da177e4 | 34 | SetPageError(page); |
6ddab3b9 PZ |
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); | |
25eaab43 GD |
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); | |
6ddab3b9 PZ |
47 | ClearPageReclaim(page); |
48 | } | |
1da177e4 LT |
49 | end_page_writeback(page); |
50 | bio_put(bio); | |
1da177e4 LT |
51 | } |
52 | ||
3f2b1a04 MK |
53 | static void swap_slot_free_notify(struct page *page) |
54 | { | |
55 | struct swap_info_struct *sis; | |
56 | struct gendisk *disk; | |
5df373e9 | 57 | swp_entry_t entry; |
3f2b1a04 MK |
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); | |
7b37e226 | 69 | if (data_race(!(sis->flags & SWP_BLKDEV))) |
3f2b1a04 MK |
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; | |
5df373e9 VM |
89 | entry.val = page_private(page); |
90 | if (disk->fops->swap_slot_free_notify && __swap_count(entry) == 1) { | |
3f2b1a04 MK |
91 | unsigned long offset; |
92 | ||
3f2b1a04 MK |
93 | offset = swp_offset(entry); |
94 | ||
95 | SetPageDirty(page); | |
96 | disk->fops->swap_slot_free_notify(sis->bdev, | |
97 | offset); | |
98 | } | |
99 | } | |
100 | ||
4246a0b6 | 101 | static void end_swap_bio_read(struct bio *bio) |
1da177e4 | 102 | { |
263663cd | 103 | struct page *page = bio_first_page_all(bio); |
23955622 | 104 | struct task_struct *waiter = bio->bi_private; |
1da177e4 | 105 | |
4e4cbee9 | 106 | if (bio->bi_status) { |
1da177e4 LT |
107 | SetPageError(page); |
108 | ClearPageUptodate(page); | |
25eaab43 GD |
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); | |
b430e9d1 | 112 | goto out; |
1da177e4 | 113 | } |
b430e9d1 MK |
114 | |
115 | SetPageUptodate(page); | |
3f2b1a04 | 116 | swap_slot_free_notify(page); |
b430e9d1 | 117 | out: |
1da177e4 | 118 | unlock_page(page); |
23955622 | 119 | WRITE_ONCE(bio->bi_private, NULL); |
1da177e4 | 120 | bio_put(bio); |
87518530 ON |
121 | if (waiter) { |
122 | blk_wake_io_task(waiter); | |
123 | put_task_struct(waiter); | |
124 | } | |
1da177e4 LT |
125 | } |
126 | ||
a509bc1a MG |
127 | int 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 | /* | |
4efaceb1 | 147 | * Map all the blocks into the extent tree. This code doesn't try |
a509bc1a MG |
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 | ||
7e4411bf MP |
158 | cond_resched(); |
159 | ||
30460e1e CM |
160 | first_block = probe_block; |
161 | ret = bmap(inode, &first_block); | |
162 | if (ret || !first_block) | |
a509bc1a MG |
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 | ||
30460e1e CM |
177 | block = probe_block + block_in_page; |
178 | ret = bmap(inode, &block); | |
179 | if (ret || !block) | |
a509bc1a | 180 | goto bad_bmap; |
30460e1e | 181 | |
a509bc1a MG |
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; | |
206 | reprobe: | |
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; | |
216 | out: | |
217 | return ret; | |
218 | bad_bmap: | |
1170532b | 219 | pr_err("swapon: swapfile has holes\n"); |
a509bc1a MG |
220 | ret = -EINVAL; |
221 | goto out; | |
222 | } | |
223 | ||
1da177e4 LT |
224 | /* |
225 | * We may have stale swap cache pages in memory: notice | |
226 | * them here and get rid of the unnecessary final write. | |
227 | */ | |
228 | int swap_writepage(struct page *page, struct writeback_control *wbc) | |
229 | { | |
2f772e6c | 230 | int ret = 0; |
1da177e4 | 231 | |
a2c43eed | 232 | if (try_to_free_swap(page)) { |
1da177e4 LT |
233 | unlock_page(page); |
234 | goto out; | |
235 | } | |
8a84802e SP |
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 | } | |
165c8aed | 246 | if (frontswap_store(page) == 0) { |
38b5faf4 DM |
247 | set_page_writeback(page); |
248 | unlock_page(page); | |
249 | end_page_writeback(page); | |
250 | goto out; | |
251 | } | |
1eec6702 | 252 | ret = __swap_writepage(page, wbc, end_swap_bio_write); |
2f772e6c SJ |
253 | out: |
254 | return ret; | |
255 | } | |
256 | ||
dd6bd0d9 MW |
257 | static sector_t swap_page_sector(struct page *page) |
258 | { | |
09cbfeaf | 259 | return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9); |
dd6bd0d9 MW |
260 | } |
261 | ||
225311a4 HY |
262 | static inline void count_swpout_vm_event(struct page *page) |
263 | { | |
264 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | |
265 | if (unlikely(PageTransHuge(page))) | |
266 | count_vm_event(THP_SWPOUT); | |
267 | #endif | |
6c357848 | 268 | count_vm_events(PSWPOUT, thp_nr_pages(page)); |
225311a4 HY |
269 | } |
270 | ||
a18b9b15 CH |
271 | #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP) |
272 | static void bio_associate_blkg_from_page(struct bio *bio, struct page *page) | |
273 | { | |
274 | struct cgroup_subsys_state *css; | |
bcfe06bf | 275 | struct mem_cgroup *memcg; |
a18b9b15 | 276 | |
bcfe06bf RG |
277 | memcg = page_memcg(page); |
278 | if (!memcg) | |
a18b9b15 CH |
279 | return; |
280 | ||
281 | rcu_read_lock(); | |
bcfe06bf | 282 | css = cgroup_e_css(memcg->css.cgroup, &io_cgrp_subsys); |
a18b9b15 CH |
283 | bio_associate_blkg_from_css(bio, css); |
284 | rcu_read_unlock(); | |
285 | } | |
286 | #else | |
287 | #define bio_associate_blkg_from_page(bio, page) do { } while (0) | |
288 | #endif /* CONFIG_MEMCG && CONFIG_BLK_CGROUP */ | |
289 | ||
1eec6702 | 290 | int __swap_writepage(struct page *page, struct writeback_control *wbc, |
4246a0b6 | 291 | bio_end_io_t end_write_func) |
2f772e6c SJ |
292 | { |
293 | struct bio *bio; | |
4e49ea4a | 294 | int ret; |
2f772e6c | 295 | struct swap_info_struct *sis = page_swap_info(page); |
62c230bc | 296 | |
cc30c5d6 | 297 | VM_BUG_ON_PAGE(!PageSwapCache(page), page); |
32646315 | 298 | if (data_race(sis->flags & SWP_FS_OPS)) { |
62c230bc MG |
299 | struct kiocb kiocb; |
300 | struct file *swap_file = sis->swap_file; | |
301 | struct address_space *mapping = swap_file->f_mapping; | |
62a8067a AV |
302 | struct bio_vec bv = { |
303 | .bv_page = page, | |
304 | .bv_len = PAGE_SIZE, | |
305 | .bv_offset = 0 | |
306 | }; | |
05afcb77 | 307 | struct iov_iter from; |
62c230bc | 308 | |
aa563d7b | 309 | iov_iter_bvec(&from, WRITE, &bv, 1, PAGE_SIZE); |
62c230bc MG |
310 | init_sync_kiocb(&kiocb, swap_file); |
311 | kiocb.ki_pos = page_file_offset(page); | |
62c230bc | 312 | |
0cdc444a | 313 | set_page_writeback(page); |
62c230bc | 314 | unlock_page(page); |
c8b8e32d | 315 | ret = mapping->a_ops->direct_IO(&kiocb, &from); |
62c230bc MG |
316 | if (ret == PAGE_SIZE) { |
317 | count_vm_event(PSWPOUT); | |
318 | ret = 0; | |
2d30d31e | 319 | } else { |
0cdc444a MG |
320 | /* |
321 | * In the case of swap-over-nfs, this can be a | |
322 | * temporary failure if the system has limited | |
323 | * memory for allocating transmit buffers. | |
324 | * Mark the page dirty and avoid | |
325 | * rotate_reclaimable_page but rate-limit the | |
326 | * messages but do not flag PageError like | |
327 | * the normal direct-to-bio case as it could | |
328 | * be temporary. | |
329 | */ | |
2d30d31e | 330 | set_page_dirty(page); |
0cdc444a | 331 | ClearPageReclaim(page); |
1170532b JP |
332 | pr_err_ratelimited("Write error on dio swapfile (%llu)\n", |
333 | page_file_offset(page)); | |
62c230bc | 334 | } |
0cdc444a | 335 | end_page_writeback(page); |
62c230bc MG |
336 | return ret; |
337 | } | |
338 | ||
dd6bd0d9 MW |
339 | ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc); |
340 | if (!ret) { | |
225311a4 | 341 | count_swpout_vm_event(page); |
dd6bd0d9 MW |
342 | return 0; |
343 | } | |
344 | ||
48d15436 CH |
345 | bio = bio_alloc(GFP_NOIO, 1); |
346 | bio_set_dev(bio, sis->bdev); | |
347 | bio->bi_iter.bi_sector = swap_page_sector(page); | |
0d1e0c7c | 348 | bio->bi_opf = REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc); |
48d15436 CH |
349 | bio->bi_end_io = end_write_func; |
350 | bio_add_page(bio, page, thp_size(page), 0); | |
351 | ||
6a7f6d86 | 352 | bio_associate_blkg_from_page(bio, page); |
225311a4 | 353 | count_swpout_vm_event(page); |
1da177e4 LT |
354 | set_page_writeback(page); |
355 | unlock_page(page); | |
4e49ea4a | 356 | submit_bio(bio); |
548d9782 ML |
357 | |
358 | return 0; | |
1da177e4 LT |
359 | } |
360 | ||
0bcac06f | 361 | int swap_readpage(struct page *page, bool synchronous) |
1da177e4 LT |
362 | { |
363 | struct bio *bio; | |
364 | int ret = 0; | |
62c230bc | 365 | struct swap_info_struct *sis = page_swap_info(page); |
23955622 | 366 | blk_qc_t qc; |
74d46992 | 367 | struct gendisk *disk; |
93779069 | 368 | unsigned long pflags; |
1da177e4 | 369 | |
0bcac06f | 370 | VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page); |
309381fe SL |
371 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
372 | VM_BUG_ON_PAGE(PageUptodate(page), page); | |
93779069 MK |
373 | |
374 | /* | |
375 | * Count submission time as memory stall. When the device is congested, | |
376 | * or the submitting cgroup IO-throttled, submission can be a | |
377 | * significant part of overall IO time. | |
378 | */ | |
379 | psi_memstall_enter(&pflags); | |
380 | ||
165c8aed | 381 | if (frontswap_load(page) == 0) { |
38b5faf4 DM |
382 | SetPageUptodate(page); |
383 | unlock_page(page); | |
384 | goto out; | |
385 | } | |
62c230bc | 386 | |
32646315 | 387 | if (data_race(sis->flags & SWP_FS_OPS)) { |
62c230bc MG |
388 | struct file *swap_file = sis->swap_file; |
389 | struct address_space *mapping = swap_file->f_mapping; | |
390 | ||
391 | ret = mapping->a_ops->readpage(swap_file, page); | |
392 | if (!ret) | |
393 | count_vm_event(PSWPIN); | |
93779069 | 394 | goto out; |
62c230bc MG |
395 | } |
396 | ||
5115db10 CH |
397 | if (sis->flags & SWP_SYNCHRONOUS_IO) { |
398 | ret = bdev_read_page(sis->bdev, swap_page_sector(page), page); | |
399 | if (!ret) { | |
400 | if (trylock_page(page)) { | |
401 | swap_slot_free_notify(page); | |
402 | unlock_page(page); | |
403 | } | |
b06bad17 | 404 | |
5115db10 CH |
405 | count_vm_event(PSWPIN); |
406 | goto out; | |
407 | } | |
dd6bd0d9 MW |
408 | } |
409 | ||
410 | ret = 0; | |
48d15436 CH |
411 | bio = bio_alloc(GFP_KERNEL, 1); |
412 | bio_set_dev(bio, sis->bdev); | |
413 | bio->bi_opf = REQ_OP_READ; | |
414 | bio->bi_iter.bi_sector = swap_page_sector(page); | |
415 | bio->bi_end_io = end_swap_bio_read; | |
416 | bio_add_page(bio, page, thp_size(page), 0); | |
417 | ||
309dca30 | 418 | disk = bio->bi_bdev->bd_disk; |
b0ba2d0f TH |
419 | /* |
420 | * Keep this task valid during swap readpage because the oom killer may | |
421 | * attempt to access it in the page fault retry time check. | |
422 | */ | |
87518530 | 423 | if (synchronous) { |
b685a735 | 424 | bio->bi_opf |= REQ_HIPRI; |
87518530 ON |
425 | get_task_struct(current); |
426 | bio->bi_private = current; | |
427 | } | |
f8891e5e | 428 | count_vm_event(PSWPIN); |
23955622 SL |
429 | bio_get(bio); |
430 | qc = submit_bio(bio); | |
0bcac06f | 431 | while (synchronous) { |
1ac5cd49 | 432 | set_current_state(TASK_UNINTERRUPTIBLE); |
23955622 SL |
433 | if (!READ_ONCE(bio->bi_private)) |
434 | break; | |
435 | ||
0a1b8b87 | 436 | if (!blk_poll(disk->queue, qc, true)) |
0f190a7a | 437 | blk_io_schedule(); |
23955622 SL |
438 | } |
439 | __set_current_state(TASK_RUNNING); | |
440 | bio_put(bio); | |
441 | ||
1da177e4 | 442 | out: |
93779069 | 443 | psi_memstall_leave(&pflags); |
1da177e4 LT |
444 | return ret; |
445 | } | |
62c230bc MG |
446 | |
447 | int swap_set_page_dirty(struct page *page) | |
448 | { | |
449 | struct swap_info_struct *sis = page_swap_info(page); | |
450 | ||
32646315 | 451 | if (data_race(sis->flags & SWP_FS_OPS)) { |
62c230bc | 452 | struct address_space *mapping = sis->swap_file->f_mapping; |
cc30c5d6 AM |
453 | |
454 | VM_BUG_ON_PAGE(!PageSwapCache(page), page); | |
62c230bc MG |
455 | return mapping->a_ops->set_page_dirty(page); |
456 | } else { | |
457 | return __set_page_dirty_no_writeback(page); | |
458 | } | |
459 | } |