/* * 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/buffer_head.h> #include <linux/writeback.h> #include <linux/frontswap.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); } int generic_swapfile_activate(struct swap_info_struct *sis, struct file *swap_file, sector_t *span) { struct address_space *mapping = swap_file->f_mapping; struct inode *inode = mapping->host; unsigned blocks_per_page; unsigned long page_no; unsigned blkbits; sector_t probe_block; sector_t last_block; sector_t lowest_block = -1; sector_t highest_block = 0; int nr_extents = 0; int ret; blkbits = inode->i_blkbits; blocks_per_page = PAGE_SIZE >> blkbits; /* * Map all the blocks into the extent list. This code doesn't try * to be very smart. */ probe_block = 0; page_no = 0; last_block = i_size_read(inode) >> blkbits; while ((probe_block + blocks_per_page) <= last_block && page_no < sis->max) { unsigned block_in_page; sector_t first_block; first_block = bmap(inode, probe_block); if (first_block == 0) goto bad_bmap; /* * It must be PAGE_SIZE aligned on-disk */ if (first_block & (blocks_per_page - 1)) { probe_block++; goto reprobe; } for (block_in_page = 1; block_in_page < blocks_per_page; block_in_page++) { sector_t block; block = bmap(inode, probe_block + block_in_page); if (block == 0) goto bad_bmap; if (block != first_block + block_in_page) { /* Discontiguity */ probe_block++; goto reprobe; } } first_block >>= (PAGE_SHIFT - blkbits); if (page_no) { /* exclude the header page */ if (first_block < lowest_block) lowest_block = first_block; if (first_block > highest_block) highest_block = first_block; } /* * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks */ ret = add_swap_extent(sis, page_no, 1, first_block); if (ret < 0) goto out; nr_extents += ret; page_no++; probe_block += blocks_per_page; reprobe: continue; } ret = nr_extents; *span = 1 + highest_block - lowest_block; if (page_no == 0) page_no = 1; /* force Empty message */ sis->max = page_no; sis->pages = page_no - 1; sis->highest_bit = page_no - 1; out: return ret; bad_bmap: printk(KERN_ERR "swapon: swapfile has holes\n"); ret = -EINVAL; goto out; } /* * 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; struct swap_info_struct *sis = page_swap_info(page); if (try_to_free_swap(page)) { unlock_page(page); goto out; } if (frontswap_store(page) == 0) { set_page_writeback(page); unlock_page(page); end_page_writeback(page); goto out; } if (sis->flags & SWP_FILE) { struct kiocb kiocb; struct file *swap_file = sis->swap_file; struct address_space *mapping = swap_file->f_mapping; struct iovec iov = { .iov_base = kmap(page), .iov_len = PAGE_SIZE, }; init_sync_kiocb(&kiocb, swap_file); kiocb.ki_pos = page_file_offset(page); kiocb.ki_left = PAGE_SIZE; kiocb.ki_nbytes = PAGE_SIZE; unlock_page(page); ret = mapping->a_ops->direct_IO(KERNEL_WRITE, &kiocb, &iov, kiocb.ki_pos, 1); kunmap(page); if (ret == PAGE_SIZE) { count_vm_event(PSWPOUT); ret = 0; } return ret; } 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 |= REQ_SYNC; 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; struct swap_info_struct *sis = page_swap_info(page); VM_BUG_ON(!PageLocked(page)); VM_BUG_ON(PageUptodate(page)); if (frontswap_load(page) == 0) { SetPageUptodate(page); unlock_page(page); goto out; } if (sis->flags & SWP_FILE) { struct file *swap_file = sis->swap_file; struct address_space *mapping = swap_file->f_mapping; ret = mapping->a_ops->readpage(swap_file, page); if (!ret) count_vm_event(PSWPIN); return ret; } 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; } int swap_set_page_dirty(struct page *page) { struct swap_info_struct *sis = page_swap_info(page); if (sis->flags & SWP_FILE) { struct address_space *mapping = sis->swap_file->f_mapping; return mapping->a_ops->set_page_dirty(page); } else { return __set_page_dirty_no_writeback(page); } }