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 LT |
36 | bio->bi_io_vec[0].bv_page = page; |
37 | bio->bi_io_vec[0].bv_len = PAGE_SIZE; | |
38 | bio->bi_io_vec[0].bv_offset = 0; | |
39 | bio->bi_vcnt = 1; | |
4f024f37 | 40 | bio->bi_iter.bi_size = PAGE_SIZE; |
1da177e4 LT |
41 | bio->bi_end_io = end_io; |
42 | } | |
43 | return bio; | |
44 | } | |
45 | ||
4246a0b6 | 46 | void end_swap_bio_write(struct bio *bio) |
1da177e4 | 47 | { |
1da177e4 LT |
48 | struct page *page = bio->bi_io_vec[0].bv_page; |
49 | ||
4246a0b6 | 50 | if (bio->bi_error) { |
1da177e4 | 51 | SetPageError(page); |
6ddab3b9 PZ |
52 | /* |
53 | * We failed to write the page out to swap-space. | |
54 | * Re-dirty the page in order to avoid it being reclaimed. | |
55 | * Also print a dire warning that things will go BAD (tm) | |
56 | * very quickly. | |
57 | * | |
58 | * Also clear PG_reclaim to avoid rotate_reclaimable_page() | |
59 | */ | |
60 | set_page_dirty(page); | |
61 | printk(KERN_ALERT "Write-error on swap-device (%u:%u:%Lu)\n", | |
62 | imajor(bio->bi_bdev->bd_inode), | |
63 | iminor(bio->bi_bdev->bd_inode), | |
4f024f37 | 64 | (unsigned long long)bio->bi_iter.bi_sector); |
6ddab3b9 PZ |
65 | ClearPageReclaim(page); |
66 | } | |
1da177e4 LT |
67 | end_page_writeback(page); |
68 | bio_put(bio); | |
1da177e4 LT |
69 | } |
70 | ||
4246a0b6 | 71 | static void end_swap_bio_read(struct bio *bio) |
1da177e4 | 72 | { |
1da177e4 LT |
73 | struct page *page = bio->bi_io_vec[0].bv_page; |
74 | ||
4246a0b6 | 75 | if (bio->bi_error) { |
1da177e4 LT |
76 | SetPageError(page); |
77 | ClearPageUptodate(page); | |
6ddab3b9 PZ |
78 | printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n", |
79 | imajor(bio->bi_bdev->bd_inode), | |
80 | iminor(bio->bi_bdev->bd_inode), | |
4f024f37 | 81 | (unsigned long long)bio->bi_iter.bi_sector); |
b430e9d1 | 82 | goto out; |
1da177e4 | 83 | } |
b430e9d1 MK |
84 | |
85 | SetPageUptodate(page); | |
86 | ||
87 | /* | |
88 | * There is no guarantee that the page is in swap cache - the software | |
89 | * suspend code (at least) uses end_swap_bio_read() against a non- | |
90 | * swapcache page. So we must check PG_swapcache before proceeding with | |
91 | * this optimization. | |
92 | */ | |
93 | if (likely(PageSwapCache(page))) { | |
94 | struct swap_info_struct *sis; | |
95 | ||
96 | sis = page_swap_info(page); | |
97 | if (sis->flags & SWP_BLKDEV) { | |
98 | /* | |
99 | * The swap subsystem performs lazy swap slot freeing, | |
100 | * expecting that the page will be swapped out again. | |
101 | * So we can avoid an unnecessary write if the page | |
102 | * isn't redirtied. | |
103 | * This is good for real swap storage because we can | |
104 | * reduce unnecessary I/O and enhance wear-leveling | |
105 | * if an SSD is used as the as swap device. | |
106 | * But if in-memory swap device (eg zram) is used, | |
107 | * this causes a duplicated copy between uncompressed | |
108 | * data in VM-owned memory and compressed data in | |
109 | * zram-owned memory. So let's free zram-owned memory | |
110 | * and make the VM-owned decompressed page *dirty*, | |
111 | * so the page should be swapped out somewhere again if | |
112 | * we again wish to reclaim it. | |
113 | */ | |
114 | struct gendisk *disk = sis->bdev->bd_disk; | |
115 | if (disk->fops->swap_slot_free_notify) { | |
116 | swp_entry_t entry; | |
117 | unsigned long offset; | |
118 | ||
119 | entry.val = page_private(page); | |
120 | offset = swp_offset(entry); | |
121 | ||
122 | SetPageDirty(page); | |
123 | disk->fops->swap_slot_free_notify(sis->bdev, | |
124 | offset); | |
125 | } | |
126 | } | |
127 | } | |
128 | ||
129 | out: | |
1da177e4 LT |
130 | unlock_page(page); |
131 | bio_put(bio); | |
1da177e4 LT |
132 | } |
133 | ||
a509bc1a MG |
134 | int generic_swapfile_activate(struct swap_info_struct *sis, |
135 | struct file *swap_file, | |
136 | sector_t *span) | |
137 | { | |
138 | struct address_space *mapping = swap_file->f_mapping; | |
139 | struct inode *inode = mapping->host; | |
140 | unsigned blocks_per_page; | |
141 | unsigned long page_no; | |
142 | unsigned blkbits; | |
143 | sector_t probe_block; | |
144 | sector_t last_block; | |
145 | sector_t lowest_block = -1; | |
146 | sector_t highest_block = 0; | |
147 | int nr_extents = 0; | |
148 | int ret; | |
149 | ||
150 | blkbits = inode->i_blkbits; | |
151 | blocks_per_page = PAGE_SIZE >> blkbits; | |
152 | ||
153 | /* | |
154 | * Map all the blocks into the extent list. This code doesn't try | |
155 | * to be very smart. | |
156 | */ | |
157 | probe_block = 0; | |
158 | page_no = 0; | |
159 | last_block = i_size_read(inode) >> blkbits; | |
160 | while ((probe_block + blocks_per_page) <= last_block && | |
161 | page_no < sis->max) { | |
162 | unsigned block_in_page; | |
163 | sector_t first_block; | |
164 | ||
165 | first_block = bmap(inode, probe_block); | |
166 | if (first_block == 0) | |
167 | goto bad_bmap; | |
168 | ||
169 | /* | |
170 | * It must be PAGE_SIZE aligned on-disk | |
171 | */ | |
172 | if (first_block & (blocks_per_page - 1)) { | |
173 | probe_block++; | |
174 | goto reprobe; | |
175 | } | |
176 | ||
177 | for (block_in_page = 1; block_in_page < blocks_per_page; | |
178 | block_in_page++) { | |
179 | sector_t block; | |
180 | ||
181 | block = bmap(inode, probe_block + block_in_page); | |
182 | if (block == 0) | |
183 | goto bad_bmap; | |
184 | if (block != first_block + block_in_page) { | |
185 | /* Discontiguity */ | |
186 | probe_block++; | |
187 | goto reprobe; | |
188 | } | |
189 | } | |
190 | ||
191 | first_block >>= (PAGE_SHIFT - blkbits); | |
192 | if (page_no) { /* exclude the header page */ | |
193 | if (first_block < lowest_block) | |
194 | lowest_block = first_block; | |
195 | if (first_block > highest_block) | |
196 | highest_block = first_block; | |
197 | } | |
198 | ||
199 | /* | |
200 | * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks | |
201 | */ | |
202 | ret = add_swap_extent(sis, page_no, 1, first_block); | |
203 | if (ret < 0) | |
204 | goto out; | |
205 | nr_extents += ret; | |
206 | page_no++; | |
207 | probe_block += blocks_per_page; | |
208 | reprobe: | |
209 | continue; | |
210 | } | |
211 | ret = nr_extents; | |
212 | *span = 1 + highest_block - lowest_block; | |
213 | if (page_no == 0) | |
214 | page_no = 1; /* force Empty message */ | |
215 | sis->max = page_no; | |
216 | sis->pages = page_no - 1; | |
217 | sis->highest_bit = page_no - 1; | |
218 | out: | |
219 | return ret; | |
220 | bad_bmap: | |
221 | printk(KERN_ERR "swapon: swapfile has holes\n"); | |
222 | ret = -EINVAL; | |
223 | goto out; | |
224 | } | |
225 | ||
1da177e4 LT |
226 | /* |
227 | * We may have stale swap cache pages in memory: notice | |
228 | * them here and get rid of the unnecessary final write. | |
229 | */ | |
230 | int swap_writepage(struct page *page, struct writeback_control *wbc) | |
231 | { | |
2f772e6c | 232 | int ret = 0; |
1da177e4 | 233 | |
a2c43eed | 234 | if (try_to_free_swap(page)) { |
1da177e4 LT |
235 | unlock_page(page); |
236 | goto out; | |
237 | } | |
165c8aed | 238 | if (frontswap_store(page) == 0) { |
38b5faf4 DM |
239 | set_page_writeback(page); |
240 | unlock_page(page); | |
241 | end_page_writeback(page); | |
242 | goto out; | |
243 | } | |
1eec6702 | 244 | ret = __swap_writepage(page, wbc, end_swap_bio_write); |
2f772e6c SJ |
245 | out: |
246 | return ret; | |
247 | } | |
248 | ||
dd6bd0d9 MW |
249 | static sector_t swap_page_sector(struct page *page) |
250 | { | |
251 | return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9); | |
252 | } | |
253 | ||
1eec6702 | 254 | int __swap_writepage(struct page *page, struct writeback_control *wbc, |
4246a0b6 | 255 | bio_end_io_t end_write_func) |
2f772e6c SJ |
256 | { |
257 | struct bio *bio; | |
dd6bd0d9 | 258 | int ret, rw = WRITE; |
2f772e6c | 259 | struct swap_info_struct *sis = page_swap_info(page); |
62c230bc MG |
260 | |
261 | if (sis->flags & SWP_FILE) { | |
262 | struct kiocb kiocb; | |
263 | struct file *swap_file = sis->swap_file; | |
264 | struct address_space *mapping = swap_file->f_mapping; | |
62a8067a AV |
265 | struct bio_vec bv = { |
266 | .bv_page = page, | |
267 | .bv_len = PAGE_SIZE, | |
268 | .bv_offset = 0 | |
269 | }; | |
05afcb77 | 270 | struct iov_iter from; |
62c230bc | 271 | |
05afcb77 | 272 | iov_iter_bvec(&from, ITER_BVEC | WRITE, &bv, 1, PAGE_SIZE); |
62c230bc MG |
273 | init_sync_kiocb(&kiocb, swap_file); |
274 | kiocb.ki_pos = page_file_offset(page); | |
62c230bc | 275 | |
0cdc444a | 276 | set_page_writeback(page); |
62c230bc | 277 | unlock_page(page); |
22c6186e | 278 | ret = mapping->a_ops->direct_IO(&kiocb, &from, kiocb.ki_pos); |
62c230bc MG |
279 | if (ret == PAGE_SIZE) { |
280 | count_vm_event(PSWPOUT); | |
281 | ret = 0; | |
2d30d31e | 282 | } else { |
0cdc444a MG |
283 | /* |
284 | * In the case of swap-over-nfs, this can be a | |
285 | * temporary failure if the system has limited | |
286 | * memory for allocating transmit buffers. | |
287 | * Mark the page dirty and avoid | |
288 | * rotate_reclaimable_page but rate-limit the | |
289 | * messages but do not flag PageError like | |
290 | * the normal direct-to-bio case as it could | |
291 | * be temporary. | |
292 | */ | |
2d30d31e | 293 | set_page_dirty(page); |
0cdc444a MG |
294 | ClearPageReclaim(page); |
295 | pr_err_ratelimited("Write error on dio swapfile (%Lu)\n", | |
296 | page_file_offset(page)); | |
62c230bc | 297 | } |
0cdc444a | 298 | end_page_writeback(page); |
62c230bc MG |
299 | return ret; |
300 | } | |
301 | ||
dd6bd0d9 MW |
302 | ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc); |
303 | if (!ret) { | |
304 | count_vm_event(PSWPOUT); | |
305 | return 0; | |
306 | } | |
307 | ||
308 | ret = 0; | |
1eec6702 | 309 | bio = get_swap_bio(GFP_NOIO, page, end_write_func); |
1da177e4 LT |
310 | if (bio == NULL) { |
311 | set_page_dirty(page); | |
312 | unlock_page(page); | |
313 | ret = -ENOMEM; | |
314 | goto out; | |
315 | } | |
316 | if (wbc->sync_mode == WB_SYNC_ALL) | |
721a9602 | 317 | rw |= REQ_SYNC; |
f8891e5e | 318 | count_vm_event(PSWPOUT); |
1da177e4 LT |
319 | set_page_writeback(page); |
320 | unlock_page(page); | |
321 | submit_bio(rw, bio); | |
322 | out: | |
323 | return ret; | |
324 | } | |
325 | ||
aca8bf32 | 326 | int swap_readpage(struct page *page) |
1da177e4 LT |
327 | { |
328 | struct bio *bio; | |
329 | int ret = 0; | |
62c230bc | 330 | struct swap_info_struct *sis = page_swap_info(page); |
1da177e4 | 331 | |
309381fe SL |
332 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
333 | VM_BUG_ON_PAGE(PageUptodate(page), page); | |
165c8aed | 334 | if (frontswap_load(page) == 0) { |
38b5faf4 DM |
335 | SetPageUptodate(page); |
336 | unlock_page(page); | |
337 | goto out; | |
338 | } | |
62c230bc MG |
339 | |
340 | if (sis->flags & SWP_FILE) { | |
341 | struct file *swap_file = sis->swap_file; | |
342 | struct address_space *mapping = swap_file->f_mapping; | |
343 | ||
344 | ret = mapping->a_ops->readpage(swap_file, page); | |
345 | if (!ret) | |
346 | count_vm_event(PSWPIN); | |
347 | return ret; | |
348 | } | |
349 | ||
dd6bd0d9 MW |
350 | ret = bdev_read_page(sis->bdev, swap_page_sector(page), page); |
351 | if (!ret) { | |
352 | count_vm_event(PSWPIN); | |
353 | return 0; | |
354 | } | |
355 | ||
356 | ret = 0; | |
f29ad6a9 | 357 | bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read); |
1da177e4 LT |
358 | if (bio == NULL) { |
359 | unlock_page(page); | |
360 | ret = -ENOMEM; | |
361 | goto out; | |
362 | } | |
f8891e5e | 363 | count_vm_event(PSWPIN); |
1da177e4 LT |
364 | submit_bio(READ, bio); |
365 | out: | |
366 | return ret; | |
367 | } | |
62c230bc MG |
368 | |
369 | int swap_set_page_dirty(struct page *page) | |
370 | { | |
371 | struct swap_info_struct *sis = page_swap_info(page); | |
372 | ||
373 | if (sis->flags & SWP_FILE) { | |
374 | struct address_space *mapping = sis->swap_file->f_mapping; | |
375 | return mapping->a_ops->set_page_dirty(page); | |
376 | } else { | |
377 | return __set_page_dirty_no_writeback(page); | |
378 | } | |
379 | } |