4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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
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>
23 static struct bio
*get_swap_bio(gfp_t gfp_flags
,
24 struct page
*page
, bio_end_io_t end_io
)
28 bio
= bio_alloc(gfp_flags
, 1);
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;
37 bio
->bi_size
= PAGE_SIZE
;
38 bio
->bi_end_io
= end_io
;
43 static void end_swap_bio_write(struct bio
*bio
, int err
)
45 const int uptodate
= test_bit(BIO_UPTODATE
, &bio
->bi_flags
);
46 struct page
*page
= bio
->bi_io_vec
[0].bv_page
;
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)
56 * Also clear PG_reclaim to avoid rotate_reclaimable_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
);
65 end_page_writeback(page
);
69 void end_swap_bio_read(struct bio
*bio
, int err
)
71 const int uptodate
= test_bit(BIO_UPTODATE
, &bio
->bi_flags
);
72 struct page
*page
= bio
->bi_io_vec
[0].bv_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
);
82 SetPageUptodate(page
);
89 * We may have stale swap cache pages in memory: notice
90 * them here and get rid of the unnecessary final write.
92 int swap_writepage(struct page
*page
, struct writeback_control
*wbc
)
95 int ret
= 0, rw
= WRITE
;
97 if (try_to_free_swap(page
)) {
101 bio
= get_swap_bio(GFP_NOIO
, page
, end_swap_bio_write
);
103 set_page_dirty(page
);
108 if (wbc
->sync_mode
== WB_SYNC_ALL
)
110 count_vm_event(PSWPOUT
);
111 set_page_writeback(page
);
118 int swap_readpage(struct page
*page
)
123 VM_BUG_ON(!PageLocked(page
));
124 VM_BUG_ON(PageUptodate(page
));
125 bio
= get_swap_bio(GFP_KERNEL
, page
, end_swap_bio_read
);
131 count_vm_event(PSWPIN
);
132 submit_bio(READ
, bio
);
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