Commit | Line | Data |
---|---|---|
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 | ||
4246a0b6 | 48 | if (bio->bi_error) { |
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 LT |
119 | struct page *page = bio->bi_io_vec[0].bv_page; |
120 | ||
4246a0b6 | 121 | if (bio->bi_error) { |
1da177e4 LT |
122 | SetPageError(page); |
123 | ClearPageUptodate(page); | |
1170532b JP |
124 | pr_alert("Read-error on swap-device (%u:%u:%llu)\n", |
125 | imajor(bio->bi_bdev->bd_inode), | |
126 | iminor(bio->bi_bdev->bd_inode), | |
127 | (unsigned long long)bio->bi_iter.bi_sector); | |
b430e9d1 | 128 | goto out; |
1da177e4 | 129 | } |
b430e9d1 MK |
130 | |
131 | SetPageUptodate(page); | |
3f2b1a04 | 132 | swap_slot_free_notify(page); |
b430e9d1 | 133 | out: |
1da177e4 LT |
134 | unlock_page(page); |
135 | bio_put(bio); | |
1da177e4 LT |
136 | } |
137 | ||
a509bc1a MG |
138 | int generic_swapfile_activate(struct swap_info_struct *sis, |
139 | struct file *swap_file, | |
140 | sector_t *span) | |
141 | { | |
142 | struct address_space *mapping = swap_file->f_mapping; | |
143 | struct inode *inode = mapping->host; | |
144 | unsigned blocks_per_page; | |
145 | unsigned long page_no; | |
146 | unsigned blkbits; | |
147 | sector_t probe_block; | |
148 | sector_t last_block; | |
149 | sector_t lowest_block = -1; | |
150 | sector_t highest_block = 0; | |
151 | int nr_extents = 0; | |
152 | int ret; | |
153 | ||
154 | blkbits = inode->i_blkbits; | |
155 | blocks_per_page = PAGE_SIZE >> blkbits; | |
156 | ||
157 | /* | |
158 | * Map all the blocks into the extent list. This code doesn't try | |
159 | * to be very smart. | |
160 | */ | |
161 | probe_block = 0; | |
162 | page_no = 0; | |
163 | last_block = i_size_read(inode) >> blkbits; | |
164 | while ((probe_block + blocks_per_page) <= last_block && | |
165 | page_no < sis->max) { | |
166 | unsigned block_in_page; | |
167 | sector_t first_block; | |
168 | ||
169 | first_block = bmap(inode, probe_block); | |
170 | if (first_block == 0) | |
171 | goto bad_bmap; | |
172 | ||
173 | /* | |
174 | * It must be PAGE_SIZE aligned on-disk | |
175 | */ | |
176 | if (first_block & (blocks_per_page - 1)) { | |
177 | probe_block++; | |
178 | goto reprobe; | |
179 | } | |
180 | ||
181 | for (block_in_page = 1; block_in_page < blocks_per_page; | |
182 | block_in_page++) { | |
183 | sector_t block; | |
184 | ||
185 | block = bmap(inode, probe_block + block_in_page); | |
186 | if (block == 0) | |
187 | goto bad_bmap; | |
188 | if (block != first_block + block_in_page) { | |
189 | /* Discontiguity */ | |
190 | probe_block++; | |
191 | goto reprobe; | |
192 | } | |
193 | } | |
194 | ||
195 | first_block >>= (PAGE_SHIFT - blkbits); | |
196 | if (page_no) { /* exclude the header page */ | |
197 | if (first_block < lowest_block) | |
198 | lowest_block = first_block; | |
199 | if (first_block > highest_block) | |
200 | highest_block = first_block; | |
201 | } | |
202 | ||
203 | /* | |
204 | * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks | |
205 | */ | |
206 | ret = add_swap_extent(sis, page_no, 1, first_block); | |
207 | if (ret < 0) | |
208 | goto out; | |
209 | nr_extents += ret; | |
210 | page_no++; | |
211 | probe_block += blocks_per_page; | |
212 | reprobe: | |
213 | continue; | |
214 | } | |
215 | ret = nr_extents; | |
216 | *span = 1 + highest_block - lowest_block; | |
217 | if (page_no == 0) | |
218 | page_no = 1; /* force Empty message */ | |
219 | sis->max = page_no; | |
220 | sis->pages = page_no - 1; | |
221 | sis->highest_bit = page_no - 1; | |
222 | out: | |
223 | return ret; | |
224 | bad_bmap: | |
1170532b | 225 | pr_err("swapon: swapfile has holes\n"); |
a509bc1a MG |
226 | ret = -EINVAL; |
227 | goto out; | |
228 | } | |
229 | ||
1da177e4 LT |
230 | /* |
231 | * We may have stale swap cache pages in memory: notice | |
232 | * them here and get rid of the unnecessary final write. | |
233 | */ | |
234 | int swap_writepage(struct page *page, struct writeback_control *wbc) | |
235 | { | |
2f772e6c | 236 | int ret = 0; |
1da177e4 | 237 | |
a2c43eed | 238 | if (try_to_free_swap(page)) { |
1da177e4 LT |
239 | unlock_page(page); |
240 | goto out; | |
241 | } | |
165c8aed | 242 | if (frontswap_store(page) == 0) { |
38b5faf4 DM |
243 | set_page_writeback(page); |
244 | unlock_page(page); | |
245 | end_page_writeback(page); | |
246 | goto out; | |
247 | } | |
1eec6702 | 248 | ret = __swap_writepage(page, wbc, end_swap_bio_write); |
2f772e6c SJ |
249 | out: |
250 | return ret; | |
251 | } | |
252 | ||
dd6bd0d9 MW |
253 | static sector_t swap_page_sector(struct page *page) |
254 | { | |
09cbfeaf | 255 | return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9); |
dd6bd0d9 MW |
256 | } |
257 | ||
1eec6702 | 258 | int __swap_writepage(struct page *page, struct writeback_control *wbc, |
4246a0b6 | 259 | bio_end_io_t end_write_func) |
2f772e6c SJ |
260 | { |
261 | struct bio *bio; | |
dd6bd0d9 | 262 | int ret, rw = WRITE; |
2f772e6c | 263 | struct swap_info_struct *sis = page_swap_info(page); |
62c230bc MG |
264 | |
265 | if (sis->flags & SWP_FILE) { | |
266 | struct kiocb kiocb; | |
267 | struct file *swap_file = sis->swap_file; | |
268 | struct address_space *mapping = swap_file->f_mapping; | |
62a8067a AV |
269 | struct bio_vec bv = { |
270 | .bv_page = page, | |
271 | .bv_len = PAGE_SIZE, | |
272 | .bv_offset = 0 | |
273 | }; | |
05afcb77 | 274 | struct iov_iter from; |
62c230bc | 275 | |
05afcb77 | 276 | iov_iter_bvec(&from, ITER_BVEC | WRITE, &bv, 1, PAGE_SIZE); |
62c230bc MG |
277 | init_sync_kiocb(&kiocb, swap_file); |
278 | kiocb.ki_pos = page_file_offset(page); | |
62c230bc | 279 | |
0cdc444a | 280 | set_page_writeback(page); |
62c230bc | 281 | unlock_page(page); |
22c6186e | 282 | ret = mapping->a_ops->direct_IO(&kiocb, &from, kiocb.ki_pos); |
62c230bc MG |
283 | if (ret == PAGE_SIZE) { |
284 | count_vm_event(PSWPOUT); | |
285 | ret = 0; | |
2d30d31e | 286 | } else { |
0cdc444a MG |
287 | /* |
288 | * In the case of swap-over-nfs, this can be a | |
289 | * temporary failure if the system has limited | |
290 | * memory for allocating transmit buffers. | |
291 | * Mark the page dirty and avoid | |
292 | * rotate_reclaimable_page but rate-limit the | |
293 | * messages but do not flag PageError like | |
294 | * the normal direct-to-bio case as it could | |
295 | * be temporary. | |
296 | */ | |
2d30d31e | 297 | set_page_dirty(page); |
0cdc444a | 298 | ClearPageReclaim(page); |
1170532b JP |
299 | pr_err_ratelimited("Write error on dio swapfile (%llu)\n", |
300 | page_file_offset(page)); | |
62c230bc | 301 | } |
0cdc444a | 302 | end_page_writeback(page); |
62c230bc MG |
303 | return ret; |
304 | } | |
305 | ||
dd6bd0d9 MW |
306 | ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc); |
307 | if (!ret) { | |
308 | count_vm_event(PSWPOUT); | |
309 | return 0; | |
310 | } | |
311 | ||
312 | ret = 0; | |
1eec6702 | 313 | bio = get_swap_bio(GFP_NOIO, page, end_write_func); |
1da177e4 LT |
314 | if (bio == NULL) { |
315 | set_page_dirty(page); | |
316 | unlock_page(page); | |
317 | ret = -ENOMEM; | |
318 | goto out; | |
319 | } | |
320 | if (wbc->sync_mode == WB_SYNC_ALL) | |
721a9602 | 321 | rw |= REQ_SYNC; |
f8891e5e | 322 | count_vm_event(PSWPOUT); |
1da177e4 LT |
323 | set_page_writeback(page); |
324 | unlock_page(page); | |
325 | submit_bio(rw, bio); | |
326 | out: | |
327 | return ret; | |
328 | } | |
329 | ||
aca8bf32 | 330 | int swap_readpage(struct page *page) |
1da177e4 LT |
331 | { |
332 | struct bio *bio; | |
333 | int ret = 0; | |
62c230bc | 334 | struct swap_info_struct *sis = page_swap_info(page); |
1da177e4 | 335 | |
309381fe SL |
336 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
337 | VM_BUG_ON_PAGE(PageUptodate(page), page); | |
165c8aed | 338 | if (frontswap_load(page) == 0) { |
38b5faf4 DM |
339 | SetPageUptodate(page); |
340 | unlock_page(page); | |
341 | goto out; | |
342 | } | |
62c230bc MG |
343 | |
344 | if (sis->flags & SWP_FILE) { | |
345 | struct file *swap_file = sis->swap_file; | |
346 | struct address_space *mapping = swap_file->f_mapping; | |
347 | ||
348 | ret = mapping->a_ops->readpage(swap_file, page); | |
349 | if (!ret) | |
350 | count_vm_event(PSWPIN); | |
351 | return ret; | |
352 | } | |
353 | ||
dd6bd0d9 MW |
354 | ret = bdev_read_page(sis->bdev, swap_page_sector(page), page); |
355 | if (!ret) { | |
b06bad17 MK |
356 | if (trylock_page(page)) { |
357 | swap_slot_free_notify(page); | |
358 | unlock_page(page); | |
359 | } | |
360 | ||
dd6bd0d9 MW |
361 | count_vm_event(PSWPIN); |
362 | return 0; | |
363 | } | |
364 | ||
365 | ret = 0; | |
f29ad6a9 | 366 | bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read); |
1da177e4 LT |
367 | if (bio == NULL) { |
368 | unlock_page(page); | |
369 | ret = -ENOMEM; | |
370 | goto out; | |
371 | } | |
f8891e5e | 372 | count_vm_event(PSWPIN); |
1da177e4 LT |
373 | submit_bio(READ, bio); |
374 | out: | |
375 | return ret; | |
376 | } | |
62c230bc MG |
377 | |
378 | int swap_set_page_dirty(struct page *page) | |
379 | { | |
380 | struct swap_info_struct *sis = page_swap_info(page); | |
381 | ||
382 | if (sis->flags & SWP_FILE) { | |
383 | struct address_space *mapping = sis->swap_file->f_mapping; | |
384 | return mapping->a_ops->set_page_dirty(page); | |
385 | } else { | |
386 | return __set_page_dirty_no_writeback(page); | |
387 | } | |
388 | } |