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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> |
a27bb332 | 23 | #include <linux/aio.h> |
1da177e4 LT |
24 | #include <asm/pgtable.h> |
25 | ||
f29ad6a9 | 26 | static struct bio *get_swap_bio(gfp_t gfp_flags, |
1da177e4 LT |
27 | struct page *page, bio_end_io_t end_io) |
28 | { | |
29 | struct bio *bio; | |
30 | ||
31 | bio = bio_alloc(gfp_flags, 1); | |
32 | if (bio) { | |
d4906e1a | 33 | bio->bi_sector = map_swap_page(page, &bio->bi_bdev); |
f29ad6a9 | 34 | bio->bi_sector <<= PAGE_SHIFT - 9; |
1da177e4 LT |
35 | bio->bi_io_vec[0].bv_page = page; |
36 | bio->bi_io_vec[0].bv_len = PAGE_SIZE; | |
37 | bio->bi_io_vec[0].bv_offset = 0; | |
38 | bio->bi_vcnt = 1; | |
39 | bio->bi_idx = 0; | |
40 | bio->bi_size = PAGE_SIZE; | |
41 | bio->bi_end_io = end_io; | |
42 | } | |
43 | return bio; | |
44 | } | |
45 | ||
1eec6702 | 46 | void end_swap_bio_write(struct bio *bio, int err) |
1da177e4 LT |
47 | { |
48 | const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); | |
49 | struct page *page = bio->bi_io_vec[0].bv_page; | |
50 | ||
6ddab3b9 | 51 | if (!uptodate) { |
1da177e4 | 52 | SetPageError(page); |
6ddab3b9 PZ |
53 | /* |
54 | * We failed to write the page out to swap-space. | |
55 | * Re-dirty the page in order to avoid it being reclaimed. | |
56 | * Also print a dire warning that things will go BAD (tm) | |
57 | * very quickly. | |
58 | * | |
59 | * Also clear PG_reclaim to avoid rotate_reclaimable_page() | |
60 | */ | |
61 | set_page_dirty(page); | |
62 | printk(KERN_ALERT "Write-error on swap-device (%u:%u:%Lu)\n", | |
63 | imajor(bio->bi_bdev->bd_inode), | |
64 | iminor(bio->bi_bdev->bd_inode), | |
65 | (unsigned long long)bio->bi_sector); | |
66 | ClearPageReclaim(page); | |
67 | } | |
1da177e4 LT |
68 | end_page_writeback(page); |
69 | bio_put(bio); | |
1da177e4 LT |
70 | } |
71 | ||
6712ecf8 | 72 | void end_swap_bio_read(struct bio *bio, int err) |
1da177e4 LT |
73 | { |
74 | const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); | |
75 | struct page *page = bio->bi_io_vec[0].bv_page; | |
76 | ||
1da177e4 LT |
77 | if (!uptodate) { |
78 | SetPageError(page); | |
79 | ClearPageUptodate(page); | |
6ddab3b9 PZ |
80 | printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n", |
81 | imajor(bio->bi_bdev->bd_inode), | |
82 | iminor(bio->bi_bdev->bd_inode), | |
83 | (unsigned long long)bio->bi_sector); | |
1da177e4 LT |
84 | } else { |
85 | SetPageUptodate(page); | |
86 | } | |
87 | unlock_page(page); | |
88 | bio_put(bio); | |
1da177e4 LT |
89 | } |
90 | ||
a509bc1a MG |
91 | int generic_swapfile_activate(struct swap_info_struct *sis, |
92 | struct file *swap_file, | |
93 | sector_t *span) | |
94 | { | |
95 | struct address_space *mapping = swap_file->f_mapping; | |
96 | struct inode *inode = mapping->host; | |
97 | unsigned blocks_per_page; | |
98 | unsigned long page_no; | |
99 | unsigned blkbits; | |
100 | sector_t probe_block; | |
101 | sector_t last_block; | |
102 | sector_t lowest_block = -1; | |
103 | sector_t highest_block = 0; | |
104 | int nr_extents = 0; | |
105 | int ret; | |
106 | ||
107 | blkbits = inode->i_blkbits; | |
108 | blocks_per_page = PAGE_SIZE >> blkbits; | |
109 | ||
110 | /* | |
111 | * Map all the blocks into the extent list. This code doesn't try | |
112 | * to be very smart. | |
113 | */ | |
114 | probe_block = 0; | |
115 | page_no = 0; | |
116 | last_block = i_size_read(inode) >> blkbits; | |
117 | while ((probe_block + blocks_per_page) <= last_block && | |
118 | page_no < sis->max) { | |
119 | unsigned block_in_page; | |
120 | sector_t first_block; | |
121 | ||
122 | first_block = bmap(inode, probe_block); | |
123 | if (first_block == 0) | |
124 | goto bad_bmap; | |
125 | ||
126 | /* | |
127 | * It must be PAGE_SIZE aligned on-disk | |
128 | */ | |
129 | if (first_block & (blocks_per_page - 1)) { | |
130 | probe_block++; | |
131 | goto reprobe; | |
132 | } | |
133 | ||
134 | for (block_in_page = 1; block_in_page < blocks_per_page; | |
135 | block_in_page++) { | |
136 | sector_t block; | |
137 | ||
138 | block = bmap(inode, probe_block + block_in_page); | |
139 | if (block == 0) | |
140 | goto bad_bmap; | |
141 | if (block != first_block + block_in_page) { | |
142 | /* Discontiguity */ | |
143 | probe_block++; | |
144 | goto reprobe; | |
145 | } | |
146 | } | |
147 | ||
148 | first_block >>= (PAGE_SHIFT - blkbits); | |
149 | if (page_no) { /* exclude the header page */ | |
150 | if (first_block < lowest_block) | |
151 | lowest_block = first_block; | |
152 | if (first_block > highest_block) | |
153 | highest_block = first_block; | |
154 | } | |
155 | ||
156 | /* | |
157 | * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks | |
158 | */ | |
159 | ret = add_swap_extent(sis, page_no, 1, first_block); | |
160 | if (ret < 0) | |
161 | goto out; | |
162 | nr_extents += ret; | |
163 | page_no++; | |
164 | probe_block += blocks_per_page; | |
165 | reprobe: | |
166 | continue; | |
167 | } | |
168 | ret = nr_extents; | |
169 | *span = 1 + highest_block - lowest_block; | |
170 | if (page_no == 0) | |
171 | page_no = 1; /* force Empty message */ | |
172 | sis->max = page_no; | |
173 | sis->pages = page_no - 1; | |
174 | sis->highest_bit = page_no - 1; | |
175 | out: | |
176 | return ret; | |
177 | bad_bmap: | |
178 | printk(KERN_ERR "swapon: swapfile has holes\n"); | |
179 | ret = -EINVAL; | |
180 | goto out; | |
181 | } | |
182 | ||
1da177e4 LT |
183 | /* |
184 | * We may have stale swap cache pages in memory: notice | |
185 | * them here and get rid of the unnecessary final write. | |
186 | */ | |
187 | int swap_writepage(struct page *page, struct writeback_control *wbc) | |
188 | { | |
2f772e6c | 189 | int ret = 0; |
1da177e4 | 190 | |
a2c43eed | 191 | if (try_to_free_swap(page)) { |
1da177e4 LT |
192 | unlock_page(page); |
193 | goto out; | |
194 | } | |
165c8aed | 195 | if (frontswap_store(page) == 0) { |
38b5faf4 DM |
196 | set_page_writeback(page); |
197 | unlock_page(page); | |
198 | end_page_writeback(page); | |
199 | goto out; | |
200 | } | |
1eec6702 | 201 | ret = __swap_writepage(page, wbc, end_swap_bio_write); |
2f772e6c SJ |
202 | out: |
203 | return ret; | |
204 | } | |
205 | ||
1eec6702 SJ |
206 | int __swap_writepage(struct page *page, struct writeback_control *wbc, |
207 | void (*end_write_func)(struct bio *, int)) | |
2f772e6c SJ |
208 | { |
209 | struct bio *bio; | |
210 | int ret = 0, rw = WRITE; | |
211 | struct swap_info_struct *sis = page_swap_info(page); | |
62c230bc MG |
212 | |
213 | if (sis->flags & SWP_FILE) { | |
214 | struct kiocb kiocb; | |
215 | struct file *swap_file = sis->swap_file; | |
216 | struct address_space *mapping = swap_file->f_mapping; | |
217 | struct iovec iov = { | |
5a178119 | 218 | .iov_base = kmap(page), |
62c230bc MG |
219 | .iov_len = PAGE_SIZE, |
220 | }; | |
221 | ||
222 | init_sync_kiocb(&kiocb, swap_file); | |
223 | kiocb.ki_pos = page_file_offset(page); | |
224 | kiocb.ki_left = PAGE_SIZE; | |
225 | kiocb.ki_nbytes = PAGE_SIZE; | |
226 | ||
0cdc444a | 227 | set_page_writeback(page); |
62c230bc MG |
228 | unlock_page(page); |
229 | ret = mapping->a_ops->direct_IO(KERNEL_WRITE, | |
230 | &kiocb, &iov, | |
231 | kiocb.ki_pos, 1); | |
5a178119 | 232 | kunmap(page); |
62c230bc MG |
233 | if (ret == PAGE_SIZE) { |
234 | count_vm_event(PSWPOUT); | |
235 | ret = 0; | |
2d30d31e | 236 | } else { |
0cdc444a MG |
237 | /* |
238 | * In the case of swap-over-nfs, this can be a | |
239 | * temporary failure if the system has limited | |
240 | * memory for allocating transmit buffers. | |
241 | * Mark the page dirty and avoid | |
242 | * rotate_reclaimable_page but rate-limit the | |
243 | * messages but do not flag PageError like | |
244 | * the normal direct-to-bio case as it could | |
245 | * be temporary. | |
246 | */ | |
2d30d31e | 247 | set_page_dirty(page); |
0cdc444a MG |
248 | ClearPageReclaim(page); |
249 | pr_err_ratelimited("Write error on dio swapfile (%Lu)\n", | |
250 | page_file_offset(page)); | |
62c230bc | 251 | } |
0cdc444a | 252 | end_page_writeback(page); |
62c230bc MG |
253 | return ret; |
254 | } | |
255 | ||
1eec6702 | 256 | bio = get_swap_bio(GFP_NOIO, page, end_write_func); |
1da177e4 LT |
257 | if (bio == NULL) { |
258 | set_page_dirty(page); | |
259 | unlock_page(page); | |
260 | ret = -ENOMEM; | |
261 | goto out; | |
262 | } | |
263 | if (wbc->sync_mode == WB_SYNC_ALL) | |
721a9602 | 264 | rw |= REQ_SYNC; |
f8891e5e | 265 | count_vm_event(PSWPOUT); |
1da177e4 LT |
266 | set_page_writeback(page); |
267 | unlock_page(page); | |
268 | submit_bio(rw, bio); | |
269 | out: | |
270 | return ret; | |
271 | } | |
272 | ||
aca8bf32 | 273 | int swap_readpage(struct page *page) |
1da177e4 LT |
274 | { |
275 | struct bio *bio; | |
276 | int ret = 0; | |
62c230bc | 277 | struct swap_info_struct *sis = page_swap_info(page); |
1da177e4 | 278 | |
51726b12 HD |
279 | VM_BUG_ON(!PageLocked(page)); |
280 | VM_BUG_ON(PageUptodate(page)); | |
165c8aed | 281 | if (frontswap_load(page) == 0) { |
38b5faf4 DM |
282 | SetPageUptodate(page); |
283 | unlock_page(page); | |
284 | goto out; | |
285 | } | |
62c230bc MG |
286 | |
287 | if (sis->flags & SWP_FILE) { | |
288 | struct file *swap_file = sis->swap_file; | |
289 | struct address_space *mapping = swap_file->f_mapping; | |
290 | ||
291 | ret = mapping->a_ops->readpage(swap_file, page); | |
292 | if (!ret) | |
293 | count_vm_event(PSWPIN); | |
294 | return ret; | |
295 | } | |
296 | ||
f29ad6a9 | 297 | bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read); |
1da177e4 LT |
298 | if (bio == NULL) { |
299 | unlock_page(page); | |
300 | ret = -ENOMEM; | |
301 | goto out; | |
302 | } | |
f8891e5e | 303 | count_vm_event(PSWPIN); |
1da177e4 LT |
304 | submit_bio(READ, bio); |
305 | out: | |
306 | return ret; | |
307 | } | |
62c230bc MG |
308 | |
309 | int swap_set_page_dirty(struct page *page) | |
310 | { | |
311 | struct swap_info_struct *sis = page_swap_info(page); | |
312 | ||
313 | if (sis->flags & SWP_FILE) { | |
314 | struct address_space *mapping = sis->swap_file->f_mapping; | |
315 | return mapping->a_ops->set_page_dirty(page); | |
316 | } else { | |
317 | return __set_page_dirty_no_writeback(page); | |
318 | } | |
319 | } |