blob: 065c4480eaf0905c8631732540a118c002989f09 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Al Virodd0fc662005-10-07 07:46:04 +010022static struct bio *get_swap_bio(gfp_t gfp_flags, pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -070023 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
NeilBrown6712ecf2007-09-27 12:47:43 +020047static void end_swap_bio_write(struct bio *bio, int err)
Linus Torvalds1da177e2005-04-16 15:20:36 -070048{
49 const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
50 struct page *page = bio->bi_io_vec[0].bv_page;
51
Peter Zijlstra6ddab3b2006-09-25 23:31:26 -070052 if (!uptodate) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 SetPageError(page);
Peter Zijlstra6ddab3b2006-09-25 23:31:26 -070054 /*
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 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 end_page_writeback(page);
70 bio_put(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -070071}
72
NeilBrown6712ecf2007-09-27 12:47:43 +020073void end_swap_bio_read(struct bio *bio, int err)
Linus Torvalds1da177e2005-04-16 15:20:36 -070074{
75 const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
76 struct page *page = bio->bi_io_vec[0].bv_page;
77
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 if (!uptodate) {
79 SetPageError(page);
80 ClearPageUptodate(page);
Peter Zijlstra6ddab3b2006-09-25 23:31:26 -070081 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);
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 } else {
86 SetPageUptodate(page);
87 }
88 unlock_page(page);
89 bio_put(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -070090}
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 */
96int swap_writepage(struct page *page, struct writeback_control *wbc)
97{
98 struct bio *bio;
99 int ret = 0, rw = WRITE;
100
101 if (remove_exclusive_swap_page(page)) {
102 unlock_page(page);
103 goto out;
104 }
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700105 bio = get_swap_bio(GFP_NOIO, page_private(page), page,
106 end_swap_bio_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 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_SYNC);
Christoph Lameterf8891e52006-06-30 01:55:45 -0700115 count_vm_event(PSWPOUT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116 set_page_writeback(page);
117 unlock_page(page);
118 submit_bio(rw, bio);
119out:
120 return ret;
121}
122
123int swap_readpage(struct file *file, struct page *page)
124{
125 struct bio *bio;
126 int ret = 0;
127
128 BUG_ON(!PageLocked(page));
Nick Piggin0ed361d2008-02-04 22:29:34 -0800129 BUG_ON(PageUptodate(page));
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700130 bio = get_swap_bio(GFP_KERNEL, page_private(page), page,
131 end_swap_bio_read);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 if (bio == NULL) {
133 unlock_page(page);
134 ret = -ENOMEM;
135 goto out;
136 }
Christoph Lameterf8891e52006-06-30 01:55:45 -0700137 count_vm_event(PSWPIN);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 submit_bio(READ, bio);
139out:
140 return ret;
141}