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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/pagemap.h> |
16 | #include <linux/swap.h> |
17 | #include <linux/bio.h> |
18 | #include <linux/swapops.h> |
19 | #include <linux/writeback.h> |
20 | #include <asm/pgtable.h> |
21 | |
22 | static struct bio *get_swap_bio(gfp_t gfp_flags, pgoff_t index, |
23 | struct page *page, bio_end_io_t end_io) |
24 | { |
25 | struct bio *bio; |
26 | |
27 | bio = bio_alloc(gfp_flags, 1); |
28 | if (bio) { |
29 | struct swap_info_struct *sis; |
30 | swp_entry_t entry = { .val = index, }; |
31 | |
32 | sis = get_swap_info_struct(swp_type(entry)); |
33 | bio->bi_sector = map_swap_page(sis, swp_offset(entry)) * |
34 | (PAGE_SIZE >> 9); |
35 | bio->bi_bdev = sis->bdev; |
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; |
40 | bio->bi_idx = 0; |
41 | bio->bi_size = PAGE_SIZE; |
42 | bio->bi_end_io = end_io; |
43 | } |
44 | return bio; |
45 | } |
46 | |
47 | static void end_swap_bio_write(struct bio *bio, int err) |
48 | { |
49 | const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); |
50 | struct page *page = bio->bi_io_vec[0].bv_page; |
51 | |
52 | if (!uptodate) { |
53 | SetPageError(page); |
54 | /* |
55 | * We failed to write the page out to swap-space. |
56 | * Re-dirty the page in order to avoid it being reclaimed. |
57 | * Also print a dire warning that things will go BAD (tm) |
58 | * very quickly. |
59 | * |
60 | * Also clear PG_reclaim to avoid rotate_reclaimable_page() |
61 | */ |
62 | set_page_dirty(page); |
63 | printk(KERN_ALERT "Write-error on swap-device (%u:%u:%Lu)\n", |
64 | imajor(bio->bi_bdev->bd_inode), |
65 | iminor(bio->bi_bdev->bd_inode), |
66 | (unsigned long long)bio->bi_sector); |
67 | ClearPageReclaim(page); |
68 | } |
69 | end_page_writeback(page); |
70 | bio_put(bio); |
71 | } |
72 | |
73 | void end_swap_bio_read(struct bio *bio, int err) |
74 | { |
75 | const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); |
76 | struct page *page = bio->bi_io_vec[0].bv_page; |
77 | |
78 | if (!uptodate) { |
79 | SetPageError(page); |
80 | ClearPageUptodate(page); |
81 | printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n", |
82 | imajor(bio->bi_bdev->bd_inode), |
83 | iminor(bio->bi_bdev->bd_inode), |
84 | (unsigned long long)bio->bi_sector); |
85 | } else { |
86 | SetPageUptodate(page); |
87 | } |
88 | unlock_page(page); |
89 | bio_put(bio); |
90 | } |
91 | |
92 | /* |
93 | * We may have stale swap cache pages in memory: notice |
94 | * them here and get rid of the unnecessary final write. |
95 | */ |
96 | int swap_writepage(struct page *page, struct writeback_control *wbc) |
97 | { |
98 | struct bio *bio; |
99 | int ret = 0, rw = WRITE; |
100 | |
101 | if (try_to_free_swap(page)) { |
102 | unlock_page(page); |
103 | goto out; |
104 | } |
105 | bio = get_swap_bio(GFP_NOIO, page_private(page), page, |
106 | end_swap_bio_write); |
107 | if (bio == NULL) { |
108 | set_page_dirty(page); |
109 | unlock_page(page); |
110 | ret = -ENOMEM; |
111 | goto out; |
112 | } |
113 | if (wbc->sync_mode == WB_SYNC_ALL) |
114 | rw |= (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG); |
115 | count_vm_event(PSWPOUT); |
116 | set_page_writeback(page); |
117 | unlock_page(page); |
118 | submit_bio(rw, bio); |
119 | out: |
120 | return ret; |
121 | } |
122 | |
123 | int swap_readpage(struct page *page) |
124 | { |
125 | struct bio *bio; |
126 | int ret = 0; |
127 | |
128 | VM_BUG_ON(!PageLocked(page)); |
129 | VM_BUG_ON(PageUptodate(page)); |
130 | bio = get_swap_bio(GFP_KERNEL, page_private(page), page, |
131 | end_swap_bio_read); |
132 | if (bio == NULL) { |
133 | unlock_page(page); |
134 | ret = -ENOMEM; |
135 | goto out; |
136 | } |
137 | count_vm_event(PSWPIN); |
138 | submit_bio(READ, bio); |
139 | out: |
140 | return ret; |
141 | } |
142 |
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