/* * 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/gfp.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(gfp_t gfp_flags, struct page *page, bio_end_io_t end_io) { struct bio *bio; bio = bio_alloc(gfp_flags, 1); if (bio) { bio->bi_sector = map_swap_page(page, &bio->bi_bdev); bio->bi_sector <<= PAGE_SHIFT - 9; 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 void end_swap_bio_write(struct bio *bio, int err) { const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); struct page *page = bio->bi_io_vec[0].bv_page; if (!uptodate) { SetPageError(page); /* * We failed to write the page out to swap-space. * Re-dirty the page in order to avoid it being reclaimed. * Also print a dire warning that things will go BAD (tm) * very quickly. * * Also clear PG_reclaim to avoid rotate_reclaimable_page() */ set_page_dirty(page); printk(KERN_ALERT "Write-error on swap-device (%u:%u:%Lu)\n", imajor(bio->bi_bdev->bd_inode), iminor(bio->bi_bdev->bd_inode), (unsigned long long)bio->bi_sector); ClearPageReclaim(page); } end_page_writeback(page); bio_put(bio); } void end_swap_bio_read(struct bio *bio, int err) { const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); struct page *page = bio->bi_io_vec[0].bv_page; if (!uptodate) { SetPageError(page); ClearPageUptodate(page); printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n", imajor(bio->bi_bdev->bd_inode), iminor(bio->bi_bdev->bd_inode), (unsigned long long)bio->bi_sector); } else { SetPageUptodate(page); } unlock_page(page); bio_put(bio); } /* * 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 (try_to_free_swap(page)) { unlock_page(page); goto out; } bio = get_swap_bio(GFP_NOIO, 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_SYNCIO) | (1 << BIO_RW_UNPLUG); count_vm_event(PSWPOUT); set_page_writeback(page); unlock_page(page); submit_bio(rw, bio); out: return ret; } int swap_readpage(struct page *page) { struct bio *bio; int ret = 0; VM_BUG_ON(!PageLocked(page)); VM_BUG_ON(PageUptodate(page)); bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read); if (bio == NULL) { unlock_page(page); ret = -ENOMEM; goto out; } count_vm_event(PSWPIN); submit_bio(READ, bio); out: return ret; }