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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> |
15 | #include <linux/gfp.h> |
16 | #include <linux/pagemap.h> |
17 | #include <linux/swap.h> |
18 | #include <linux/bio.h> |
19 | #include <linux/swapops.h> |
20 | #include <linux/writeback.h> |
21 | #include <asm/pgtable.h> |
22 | |
23 | static struct bio *get_swap_bio(gfp_t gfp_flags, |
24 | struct page *page, bio_end_io_t end_io) |
25 | { |
26 | struct bio *bio; |
27 | |
28 | bio = bio_alloc(gfp_flags, 1); |
29 | if (bio) { |
30 | bio->bi_sector = map_swap_page(page, &bio->bi_bdev); |
31 | bio->bi_sector <<= PAGE_SHIFT - 9; |
32 | bio->bi_io_vec[0].bv_page = page; |
33 | bio->bi_io_vec[0].bv_len = PAGE_SIZE; |
34 | bio->bi_io_vec[0].bv_offset = 0; |
35 | bio->bi_vcnt = 1; |
36 | bio->bi_idx = 0; |
37 | bio->bi_size = PAGE_SIZE; |
38 | bio->bi_end_io = end_io; |
39 | } |
40 | return bio; |
41 | } |
42 | |
43 | static void end_swap_bio_write(struct bio *bio, int err) |
44 | { |
45 | const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); |
46 | struct page *page = bio->bi_io_vec[0].bv_page; |
47 | |
48 | if (!uptodate) { |
49 | SetPageError(page); |
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); |
59 | printk(KERN_ALERT "Write-error on swap-device (%u:%u:%Lu)\n", |
60 | imajor(bio->bi_bdev->bd_inode), |
61 | iminor(bio->bi_bdev->bd_inode), |
62 | (unsigned long long)bio->bi_sector); |
63 | ClearPageReclaim(page); |
64 | } |
65 | end_page_writeback(page); |
66 | bio_put(bio); |
67 | } |
68 | |
69 | void end_swap_bio_read(struct bio *bio, int err) |
70 | { |
71 | const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); |
72 | struct page *page = bio->bi_io_vec[0].bv_page; |
73 | |
74 | if (!uptodate) { |
75 | SetPageError(page); |
76 | ClearPageUptodate(page); |
77 | printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n", |
78 | imajor(bio->bi_bdev->bd_inode), |
79 | iminor(bio->bi_bdev->bd_inode), |
80 | (unsigned long long)bio->bi_sector); |
81 | } else { |
82 | SetPageUptodate(page); |
83 | } |
84 | unlock_page(page); |
85 | bio_put(bio); |
86 | } |
87 | |
88 | /* |
89 | * We may have stale swap cache pages in memory: notice |
90 | * them here and get rid of the unnecessary final write. |
91 | */ |
92 | int swap_writepage(struct page *page, struct writeback_control *wbc) |
93 | { |
94 | struct bio *bio; |
95 | int ret = 0, rw = WRITE; |
96 | |
97 | if (try_to_free_swap(page)) { |
98 | unlock_page(page); |
99 | goto out; |
100 | } |
101 | bio = get_swap_bio(GFP_NOIO, page, end_swap_bio_write); |
102 | if (bio == NULL) { |
103 | set_page_dirty(page); |
104 | unlock_page(page); |
105 | ret = -ENOMEM; |
106 | goto out; |
107 | } |
108 | if (wbc->sync_mode == WB_SYNC_ALL) |
109 | rw |= REQ_SYNC; |
110 | count_vm_event(PSWPOUT); |
111 | set_page_writeback(page); |
112 | unlock_page(page); |
113 | submit_bio(rw, bio); |
114 | out: |
115 | return ret; |
116 | } |
117 | |
118 | int swap_readpage(struct page *page) |
119 | { |
120 | struct bio *bio; |
121 | int ret = 0; |
122 | |
123 | VM_BUG_ON(!PageLocked(page)); |
124 | VM_BUG_ON(PageUptodate(page)); |
125 | bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read); |
126 | if (bio == NULL) { |
127 | unlock_page(page); |
128 | ret = -ENOMEM; |
129 | goto out; |
130 | } |
131 | count_vm_event(PSWPIN); |
132 | submit_bio(READ, bio); |
133 | out: |
134 | return ret; |
135 | } |
136 |
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