diff options
Diffstat (limited to 'mm/page_io.c')
| -rw-r--r-- | mm/page_io.c | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/mm/page_io.c b/mm/page_io.c new file mode 100644 index 000000000000..667c76df1ec2 --- /dev/null +++ b/mm/page_io.c @@ -0,0 +1,160 @@ +/* + * linux/mm/page_io.c + * + * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds + * + * Swap reorganised 29.12.95, + * Asynchronous swapping added 30.12.95. Stephen Tweedie + * Removed race in async swapping. 14.4.1996. Bruno Haible + * Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie + * Always use brw_page, life becomes simpler. 12 May 1998 Eric Biederman + */ + +#include <linux/mm.h> +#include <linux/kernel_stat.h> +#include <linux/pagemap.h> +#include <linux/swap.h> +#include <linux/bio.h> +#include <linux/swapops.h> +#include <linux/writeback.h> +#include <asm/pgtable.h> + +static struct bio *get_swap_bio(unsigned int __nocast gfp_flags, pgoff_t index, + struct page *page, bio_end_io_t end_io) +{ + struct bio *bio; + + bio = bio_alloc(gfp_flags, 1); + if (bio) { + struct swap_info_struct *sis; + swp_entry_t entry = { .val = index, }; + + sis = get_swap_info_struct(swp_type(entry)); + bio->bi_sector = map_swap_page(sis, swp_offset(entry)) * + (PAGE_SIZE >> 9); + bio->bi_bdev = sis->bdev; + bio->bi_io_vec[0].bv_page = page; + bio->bi_io_vec[0].bv_len = PAGE_SIZE; + bio->bi_io_vec[0].bv_offset = 0; + bio->bi_vcnt = 1; + bio->bi_idx = 0; + bio->bi_size = PAGE_SIZE; + bio->bi_end_io = end_io; + } + return bio; +} + +static int end_swap_bio_write(struct bio *bio, unsigned int bytes_done, int err) +{ + const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); + struct page *page = bio->bi_io_vec[0].bv_page; + + if (bio->bi_size) + return 1; + + if (!uptodate) + SetPageError(page); + end_page_writeback(page); + bio_put(bio); + return 0; +} + +static int end_swap_bio_read(struct bio *bio, unsigned int bytes_done, int err) +{ + const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); + struct page *page = bio->bi_io_vec[0].bv_page; + + if (bio->bi_size) + return 1; + + if (!uptodate) { + SetPageError(page); + ClearPageUptodate(page); + } else { + SetPageUptodate(page); + } + unlock_page(page); + bio_put(bio); + return 0; +} + +/* + * We may have stale swap cache pages in memory: notice + * them here and get rid of the unnecessary final write. + */ +int swap_writepage(struct page *page, struct writeback_control *wbc) +{ + struct bio *bio; + int ret = 0, rw = WRITE; + + if (remove_exclusive_swap_page(page)) { + unlock_page(page); + goto out; + } + bio = get_swap_bio(GFP_NOIO, page->private, page, end_swap_bio_write); + if (bio == NULL) { + set_page_dirty(page); + unlock_page(page); + ret = -ENOMEM; + goto out; + } + if (wbc->sync_mode == WB_SYNC_ALL) + rw |= (1 << BIO_RW_SYNC); + inc_page_state(pswpout); + set_page_writeback(page); + unlock_page(page); + submit_bio(rw, bio); +out: + return ret; +} + +int swap_readpage(struct file *file, struct page *page) +{ + struct bio *bio; + int ret = 0; + + BUG_ON(!PageLocked(page)); + ClearPageUptodate(page); + bio = get_swap_bio(GFP_KERNEL, page->private, page, end_swap_bio_read); + if (bio == NULL) { + unlock_page(page); + ret = -ENOMEM; + goto out; + } + inc_page_state(pswpin); + submit_bio(READ, bio); +out: + return ret; +} + +#if defined(CONFIG_SOFTWARE_SUSPEND) || defined(CONFIG_PM_DISK) +/* + * A scruffy utility function to read or write an arbitrary swap page + * and wait on the I/O. The caller must have a ref on the page. + * + * We use end_swap_bio_read() even for writes, because it happens to do what + * we want. + */ +int rw_swap_page_sync(int rw, swp_entry_t entry, struct page *page) +{ + struct bio *bio; + int ret = 0; + + lock_page(page); + + bio = get_swap_bio(GFP_KERNEL, entry.val, page, end_swap_bio_read); + if (bio == NULL) { + unlock_page(page); + ret = -ENOMEM; + goto out; + } + + submit_bio(rw | (1 << BIO_RW_SYNC), bio); + wait_on_page_locked(page); + + if (!PageUptodate(page) || PageError(page)) + ret = -EIO; +out: + return ret; +} +#endif |