mm/page_io.c - pub/scm/linux/kernel/git/jes/staging - Git at Google

 /*
  *  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);
 	}
 }
	/*
	* 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);
	}
	}