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