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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/page_io.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * | |
6 | * Swap reorganised 29.12.95, | |
7 | * Asynchronous swapping added 30.12.95. Stephen Tweedie | |
8 | * Removed race in async swapping. 14.4.1996. Bruno Haible | |
9 | * Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie | |
10 | * Always use brw_page, life becomes simpler. 12 May 1998 Eric Biederman | |
11 | */ | |
12 | ||
13 | #include <linux/mm.h> | |
14 | #include <linux/kernel_stat.h> | |
5a0e3ad6 | 15 | #include <linux/gfp.h> |
1da177e4 LT |
16 | #include <linux/pagemap.h> |
17 | #include <linux/swap.h> | |
18 | #include <linux/bio.h> | |
19 | #include <linux/swapops.h> | |
62c230bc | 20 | #include <linux/buffer_head.h> |
1da177e4 | 21 | #include <linux/writeback.h> |
38b5faf4 | 22 | #include <linux/frontswap.h> |
b430e9d1 | 23 | #include <linux/blkdev.h> |
e2e40f2c | 24 | #include <linux/uio.h> |
1da177e4 LT |
25 | #include <asm/pgtable.h> |
26 | ||
f29ad6a9 | 27 | static struct bio *get_swap_bio(gfp_t gfp_flags, |
1da177e4 LT |
28 | struct page *page, bio_end_io_t end_io) |
29 | { | |
30 | struct bio *bio; | |
31 | ||
32 | bio = bio_alloc(gfp_flags, 1); | |
33 | if (bio) { | |
4f024f37 KO |
34 | bio->bi_iter.bi_sector = map_swap_page(page, &bio->bi_bdev); |
35 | bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9; | |
1da177e4 | 36 | bio->bi_end_io = end_io; |
6cf66b4c KO |
37 | |
38 | bio_add_page(bio, page, PAGE_SIZE, 0); | |
39 | BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE); | |
1da177e4 LT |
40 | } |
41 | return bio; | |
42 | } | |
43 | ||
4246a0b6 | 44 | void end_swap_bio_write(struct bio *bio) |
1da177e4 | 45 | { |
1da177e4 LT |
46 | struct page *page = bio->bi_io_vec[0].bv_page; |
47 | ||
4e4cbee9 | 48 | if (bio->bi_status) { |
1da177e4 | 49 | SetPageError(page); |
6ddab3b9 PZ |
50 | /* |
51 | * We failed to write the page out to swap-space. | |
52 | * Re-dirty the page in order to avoid it being reclaimed. | |
53 | * Also print a dire warning that things will go BAD (tm) | |
54 | * very quickly. | |
55 | * | |
56 | * Also clear PG_reclaim to avoid rotate_reclaimable_page() | |
57 | */ | |
58 | set_page_dirty(page); | |
1170532b JP |
59 | pr_alert("Write-error on swap-device (%u:%u:%llu)\n", |
60 | imajor(bio->bi_bdev->bd_inode), | |
61 | iminor(bio->bi_bdev->bd_inode), | |
62 | (unsigned long long)bio->bi_iter.bi_sector); | |
6ddab3b9 PZ |
63 | ClearPageReclaim(page); |
64 | } | |
1da177e4 LT |
65 | end_page_writeback(page); |
66 | bio_put(bio); | |
1da177e4 LT |
67 | } |
68 | ||
3f2b1a04 MK |
69 | static void swap_slot_free_notify(struct page *page) |
70 | { | |
71 | struct swap_info_struct *sis; | |
72 | struct gendisk *disk; | |
73 | ||
74 | /* | |
75 | * There is no guarantee that the page is in swap cache - the software | |
76 | * suspend code (at least) uses end_swap_bio_read() against a non- | |
77 | * swapcache page. So we must check PG_swapcache before proceeding with | |
78 | * this optimization. | |
79 | */ | |
80 | if (unlikely(!PageSwapCache(page))) | |
81 | return; | |
82 | ||
83 | sis = page_swap_info(page); | |
84 | if (!(sis->flags & SWP_BLKDEV)) | |
85 | return; | |
86 | ||
87 | /* | |
88 | * The swap subsystem performs lazy swap slot freeing, | |
89 | * expecting that the page will be swapped out again. | |
90 | * So we can avoid an unnecessary write if the page | |
91 | * isn't redirtied. | |
92 | * This is good for real swap storage because we can | |
93 | * reduce unnecessary I/O and enhance wear-leveling | |
94 | * if an SSD is used as the as swap device. | |
95 | * But if in-memory swap device (eg zram) is used, | |
96 | * this causes a duplicated copy between uncompressed | |
97 | * data in VM-owned memory and compressed data in | |
98 | * zram-owned memory. So let's free zram-owned memory | |
99 | * and make the VM-owned decompressed page *dirty*, | |
100 | * so the page should be swapped out somewhere again if | |
101 | * we again wish to reclaim it. | |
102 | */ | |
103 | disk = sis->bdev->bd_disk; | |
104 | if (disk->fops->swap_slot_free_notify) { | |
105 | swp_entry_t entry; | |
106 | unsigned long offset; | |
107 | ||
108 | entry.val = page_private(page); | |
109 | offset = swp_offset(entry); | |
110 | ||
111 | SetPageDirty(page); | |
112 | disk->fops->swap_slot_free_notify(sis->bdev, | |
113 | offset); | |
114 | } | |
115 | } | |
116 | ||
4246a0b6 | 117 | static void end_swap_bio_read(struct bio *bio) |
1da177e4 | 118 | { |
1da177e4 | 119 | struct page *page = bio->bi_io_vec[0].bv_page; |
23955622 | 120 | struct task_struct *waiter = bio->bi_private; |
1da177e4 | 121 | |
4e4cbee9 | 122 | if (bio->bi_status) { |
1da177e4 LT |
123 | SetPageError(page); |
124 | ClearPageUptodate(page); | |
1170532b JP |
125 | pr_alert("Read-error on swap-device (%u:%u:%llu)\n", |
126 | imajor(bio->bi_bdev->bd_inode), | |
127 | iminor(bio->bi_bdev->bd_inode), | |
128 | (unsigned long long)bio->bi_iter.bi_sector); | |
b430e9d1 | 129 | goto out; |
1da177e4 | 130 | } |
b430e9d1 MK |
131 | |
132 | SetPageUptodate(page); | |
3f2b1a04 | 133 | swap_slot_free_notify(page); |
b430e9d1 | 134 | out: |
1da177e4 | 135 | unlock_page(page); |
23955622 | 136 | WRITE_ONCE(bio->bi_private, NULL); |
1da177e4 | 137 | bio_put(bio); |
23955622 | 138 | wake_up_process(waiter); |
1da177e4 LT |
139 | } |
140 | ||
a509bc1a MG |
141 | int generic_swapfile_activate(struct swap_info_struct *sis, |
142 | struct file *swap_file, | |
143 | sector_t *span) | |
144 | { | |
145 | struct address_space *mapping = swap_file->f_mapping; | |
146 | struct inode *inode = mapping->host; | |
147 | unsigned blocks_per_page; | |
148 | unsigned long page_no; | |
149 | unsigned blkbits; | |
150 | sector_t probe_block; | |
151 | sector_t last_block; | |
152 | sector_t lowest_block = -1; | |
153 | sector_t highest_block = 0; | |
154 | int nr_extents = 0; | |
155 | int ret; | |
156 | ||
157 | blkbits = inode->i_blkbits; | |
158 | blocks_per_page = PAGE_SIZE >> blkbits; | |
159 | ||
160 | /* | |
161 | * Map all the blocks into the extent list. This code doesn't try | |
162 | * to be very smart. | |
163 | */ | |
164 | probe_block = 0; | |
165 | page_no = 0; | |
166 | last_block = i_size_read(inode) >> blkbits; | |
167 | while ((probe_block + blocks_per_page) <= last_block && | |
168 | page_no < sis->max) { | |
169 | unsigned block_in_page; | |
170 | sector_t first_block; | |
171 | ||
7e4411bf MP |
172 | cond_resched(); |
173 | ||
a509bc1a MG |
174 | first_block = bmap(inode, probe_block); |
175 | if (first_block == 0) | |
176 | goto bad_bmap; | |
177 | ||
178 | /* | |
179 | * It must be PAGE_SIZE aligned on-disk | |
180 | */ | |
181 | if (first_block & (blocks_per_page - 1)) { | |
182 | probe_block++; | |
183 | goto reprobe; | |
184 | } | |
185 | ||
186 | for (block_in_page = 1; block_in_page < blocks_per_page; | |
187 | block_in_page++) { | |
188 | sector_t block; | |
189 | ||
190 | block = bmap(inode, probe_block + block_in_page); | |
191 | if (block == 0) | |
192 | goto bad_bmap; | |
193 | if (block != first_block + block_in_page) { | |
194 | /* Discontiguity */ | |
195 | probe_block++; | |
196 | goto reprobe; | |
197 | } | |
198 | } | |
199 | ||
200 | first_block >>= (PAGE_SHIFT - blkbits); | |
201 | if (page_no) { /* exclude the header page */ | |
202 | if (first_block < lowest_block) | |
203 | lowest_block = first_block; | |
204 | if (first_block > highest_block) | |
205 | highest_block = first_block; | |
206 | } | |
207 | ||
208 | /* | |
209 | * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks | |
210 | */ | |
211 | ret = add_swap_extent(sis, page_no, 1, first_block); | |
212 | if (ret < 0) | |
213 | goto out; | |
214 | nr_extents += ret; | |
215 | page_no++; | |
216 | probe_block += blocks_per_page; | |
217 | reprobe: | |
218 | continue; | |
219 | } | |
220 | ret = nr_extents; | |
221 | *span = 1 + highest_block - lowest_block; | |
222 | if (page_no == 0) | |
223 | page_no = 1; /* force Empty message */ | |
224 | sis->max = page_no; | |
225 | sis->pages = page_no - 1; | |
226 | sis->highest_bit = page_no - 1; | |
227 | out: | |
228 | return ret; | |
229 | bad_bmap: | |
1170532b | 230 | pr_err("swapon: swapfile has holes\n"); |
a509bc1a MG |
231 | ret = -EINVAL; |
232 | goto out; | |
233 | } | |
234 | ||
1da177e4 LT |
235 | /* |
236 | * We may have stale swap cache pages in memory: notice | |
237 | * them here and get rid of the unnecessary final write. | |
238 | */ | |
239 | int swap_writepage(struct page *page, struct writeback_control *wbc) | |
240 | { | |
2f772e6c | 241 | int ret = 0; |
1da177e4 | 242 | |
a2c43eed | 243 | if (try_to_free_swap(page)) { |
1da177e4 LT |
244 | unlock_page(page); |
245 | goto out; | |
246 | } | |
165c8aed | 247 | if (frontswap_store(page) == 0) { |
38b5faf4 DM |
248 | set_page_writeback(page); |
249 | unlock_page(page); | |
250 | end_page_writeback(page); | |
251 | goto out; | |
252 | } | |
1eec6702 | 253 | ret = __swap_writepage(page, wbc, end_swap_bio_write); |
2f772e6c SJ |
254 | out: |
255 | return ret; | |
256 | } | |
257 | ||
dd6bd0d9 MW |
258 | static sector_t swap_page_sector(struct page *page) |
259 | { | |
09cbfeaf | 260 | return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9); |
dd6bd0d9 MW |
261 | } |
262 | ||
1eec6702 | 263 | int __swap_writepage(struct page *page, struct writeback_control *wbc, |
4246a0b6 | 264 | bio_end_io_t end_write_func) |
2f772e6c SJ |
265 | { |
266 | struct bio *bio; | |
4e49ea4a | 267 | int ret; |
2f772e6c | 268 | struct swap_info_struct *sis = page_swap_info(page); |
62c230bc | 269 | |
cc30c5d6 | 270 | VM_BUG_ON_PAGE(!PageSwapCache(page), page); |
62c230bc MG |
271 | if (sis->flags & SWP_FILE) { |
272 | struct kiocb kiocb; | |
273 | struct file *swap_file = sis->swap_file; | |
274 | struct address_space *mapping = swap_file->f_mapping; | |
62a8067a AV |
275 | struct bio_vec bv = { |
276 | .bv_page = page, | |
277 | .bv_len = PAGE_SIZE, | |
278 | .bv_offset = 0 | |
279 | }; | |
05afcb77 | 280 | struct iov_iter from; |
62c230bc | 281 | |
05afcb77 | 282 | iov_iter_bvec(&from, ITER_BVEC | WRITE, &bv, 1, PAGE_SIZE); |
62c230bc MG |
283 | init_sync_kiocb(&kiocb, swap_file); |
284 | kiocb.ki_pos = page_file_offset(page); | |
62c230bc | 285 | |
0cdc444a | 286 | set_page_writeback(page); |
62c230bc | 287 | unlock_page(page); |
c8b8e32d | 288 | ret = mapping->a_ops->direct_IO(&kiocb, &from); |
62c230bc MG |
289 | if (ret == PAGE_SIZE) { |
290 | count_vm_event(PSWPOUT); | |
291 | ret = 0; | |
2d30d31e | 292 | } else { |
0cdc444a MG |
293 | /* |
294 | * In the case of swap-over-nfs, this can be a | |
295 | * temporary failure if the system has limited | |
296 | * memory for allocating transmit buffers. | |
297 | * Mark the page dirty and avoid | |
298 | * rotate_reclaimable_page but rate-limit the | |
299 | * messages but do not flag PageError like | |
300 | * the normal direct-to-bio case as it could | |
301 | * be temporary. | |
302 | */ | |
2d30d31e | 303 | set_page_dirty(page); |
0cdc444a | 304 | ClearPageReclaim(page); |
1170532b JP |
305 | pr_err_ratelimited("Write error on dio swapfile (%llu)\n", |
306 | page_file_offset(page)); | |
62c230bc | 307 | } |
0cdc444a | 308 | end_page_writeback(page); |
62c230bc MG |
309 | return ret; |
310 | } | |
311 | ||
dd6bd0d9 MW |
312 | ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc); |
313 | if (!ret) { | |
314 | count_vm_event(PSWPOUT); | |
315 | return 0; | |
316 | } | |
317 | ||
318 | ret = 0; | |
1eec6702 | 319 | bio = get_swap_bio(GFP_NOIO, page, end_write_func); |
1da177e4 LT |
320 | if (bio == NULL) { |
321 | set_page_dirty(page); | |
322 | unlock_page(page); | |
323 | ret = -ENOMEM; | |
324 | goto out; | |
325 | } | |
7637241e | 326 | bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc); |
f8891e5e | 327 | count_vm_event(PSWPOUT); |
1da177e4 LT |
328 | set_page_writeback(page); |
329 | unlock_page(page); | |
4e49ea4a | 330 | submit_bio(bio); |
1da177e4 LT |
331 | out: |
332 | return ret; | |
333 | } | |
334 | ||
23955622 | 335 | int swap_readpage(struct page *page, bool do_poll) |
1da177e4 LT |
336 | { |
337 | struct bio *bio; | |
338 | int ret = 0; | |
62c230bc | 339 | struct swap_info_struct *sis = page_swap_info(page); |
23955622 SL |
340 | blk_qc_t qc; |
341 | struct block_device *bdev; | |
1da177e4 | 342 | |
cc30c5d6 | 343 | VM_BUG_ON_PAGE(!PageSwapCache(page), page); |
309381fe SL |
344 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
345 | VM_BUG_ON_PAGE(PageUptodate(page), page); | |
165c8aed | 346 | if (frontswap_load(page) == 0) { |
38b5faf4 DM |
347 | SetPageUptodate(page); |
348 | unlock_page(page); | |
349 | goto out; | |
350 | } | |
62c230bc MG |
351 | |
352 | if (sis->flags & SWP_FILE) { | |
353 | struct file *swap_file = sis->swap_file; | |
354 | struct address_space *mapping = swap_file->f_mapping; | |
355 | ||
356 | ret = mapping->a_ops->readpage(swap_file, page); | |
357 | if (!ret) | |
358 | count_vm_event(PSWPIN); | |
359 | return ret; | |
360 | } | |
361 | ||
dd6bd0d9 MW |
362 | ret = bdev_read_page(sis->bdev, swap_page_sector(page), page); |
363 | if (!ret) { | |
b06bad17 MK |
364 | if (trylock_page(page)) { |
365 | swap_slot_free_notify(page); | |
366 | unlock_page(page); | |
367 | } | |
368 | ||
dd6bd0d9 MW |
369 | count_vm_event(PSWPIN); |
370 | return 0; | |
371 | } | |
372 | ||
373 | ret = 0; | |
f29ad6a9 | 374 | bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read); |
1da177e4 LT |
375 | if (bio == NULL) { |
376 | unlock_page(page); | |
377 | ret = -ENOMEM; | |
378 | goto out; | |
379 | } | |
23955622 SL |
380 | bdev = bio->bi_bdev; |
381 | bio->bi_private = current; | |
95fe6c1a | 382 | bio_set_op_attrs(bio, REQ_OP_READ, 0); |
f8891e5e | 383 | count_vm_event(PSWPIN); |
23955622 SL |
384 | bio_get(bio); |
385 | qc = submit_bio(bio); | |
386 | while (do_poll) { | |
387 | set_current_state(TASK_UNINTERRUPTIBLE); | |
388 | if (!READ_ONCE(bio->bi_private)) | |
389 | break; | |
390 | ||
391 | if (!blk_mq_poll(bdev_get_queue(bdev), qc)) | |
392 | break; | |
393 | } | |
394 | __set_current_state(TASK_RUNNING); | |
395 | bio_put(bio); | |
396 | ||
1da177e4 LT |
397 | out: |
398 | return ret; | |
399 | } | |
62c230bc MG |
400 | |
401 | int swap_set_page_dirty(struct page *page) | |
402 | { | |
403 | struct swap_info_struct *sis = page_swap_info(page); | |
404 | ||
405 | if (sis->flags & SWP_FILE) { | |
406 | struct address_space *mapping = sis->swap_file->f_mapping; | |
cc30c5d6 AM |
407 | |
408 | VM_BUG_ON_PAGE(!PageSwapCache(page), page); | |
62c230bc MG |
409 | return mapping->a_ops->set_page_dirty(page); |
410 | } else { | |
411 | return __set_page_dirty_no_writeback(page); | |
412 | } | |
413 | } |