[linux-2.6-block.git] / mm / page_io.c

/*
 *  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 <linux/blkdev.h>
#include <linux/uio.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_iter.bi_sector = map_swap_page(page, &bio->bi_bdev);
		bio->bi_iter.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_iter.bi_size = PAGE_SIZE;
		bio->bi_end_io = end_io;
	}
	return bio;
}

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_iter.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_iter.bi_sector);
		goto out;
	}

	SetPageUptodate(page);

	/*
	 * There is no guarantee that the page is in swap cache - the software
	 * suspend code (at least) uses end_swap_bio_read() against a non-
	 * swapcache page.  So we must check PG_swapcache before proceeding with
	 * this optimization.
	 */
	if (likely(PageSwapCache(page))) {
		struct swap_info_struct *sis;

		sis = page_swap_info(page);
		if (sis->flags & SWP_BLKDEV) {
			/*
			 * The swap subsystem performs lazy swap slot freeing,
			 * expecting that the page will be swapped out again.
			 * So we can avoid an unnecessary write if the page
			 * isn't redirtied.
			 * This is good for real swap storage because we can
			 * reduce unnecessary I/O and enhance wear-leveling
			 * if an SSD is used as the as swap device.
			 * But if in-memory swap device (eg zram) is used,
			 * this causes a duplicated copy between uncompressed
			 * data in VM-owned memory and compressed data in
			 * zram-owned memory.  So let's free zram-owned memory
			 * and make the VM-owned decompressed page *dirty*,
			 * so the page should be swapped out somewhere again if
			 * we again wish to reclaim it.
			 */
			struct gendisk *disk = sis->bdev->bd_disk;
			if (disk->fops->swap_slot_free_notify) {
				swp_entry_t entry;
				unsigned long offset;

				entry.val = page_private(page);
				offset = swp_offset(entry);

				SetPageDirty(page);
				disk->fops->swap_slot_free_notify(sis->bdev,
						offset);
			}
		}
	}

out:
	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)
{
	int ret = 0;

	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;
	}
	ret = __swap_writepage(page, wbc, end_swap_bio_write);
out:
	return ret;
}

static sector_t swap_page_sector(struct page *page)
{
	return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9);
}

int __swap_writepage(struct page *page, struct writeback_control *wbc,
	void (*end_write_func)(struct bio *, int))
{
	struct bio *bio;
	int ret, rw = WRITE;
	struct swap_info_struct *sis = page_swap_info(page);

	if (sis->flags & SWP_FILE) {
		struct kiocb kiocb;
		struct file *swap_file = sis->swap_file;
		struct address_space *mapping = swap_file->f_mapping;
		struct bio_vec bv = {
			.bv_page = page,
			.bv_len  = PAGE_SIZE,
			.bv_offset = 0
		};
		struct iov_iter from;

		iov_iter_bvec(&from, ITER_BVEC | WRITE, &bv, 1, PAGE_SIZE);
		init_sync_kiocb(&kiocb, swap_file);
		kiocb.ki_pos = page_file_offset(page);

		set_page_writeback(page);
		unlock_page(page);
		ret = mapping->a_ops->direct_IO(&kiocb, &from, kiocb.ki_pos);
		if (ret == PAGE_SIZE) {
			count_vm_event(PSWPOUT);
			ret = 0;
		} else {
			/*
			 * In the case of swap-over-nfs, this can be a
			 * temporary failure if the system has limited
			 * memory for allocating transmit buffers.
			 * Mark the page dirty and avoid
			 * rotate_reclaimable_page but rate-limit the
			 * messages but do not flag PageError like
			 * the normal direct-to-bio case as it could
			 * be temporary.
			 */
			set_page_dirty(page);
			ClearPageReclaim(page);
			pr_err_ratelimited("Write error on dio swapfile (%Lu)\n",
				page_file_offset(page));
		}
		end_page_writeback(page);
		return ret;
	}

	ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
	if (!ret) {
		count_vm_event(PSWPOUT);
		return 0;
	}

	ret = 0;
	bio = get_swap_bio(GFP_NOIO, page, end_write_func);
	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_PAGE(!PageLocked(page), page);
	VM_BUG_ON_PAGE(PageUptodate(page), 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;
	}

	ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
	if (!ret) {
		count_vm_event(PSWPIN);
		return 0;
	}

	ret = 0;
	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);
	}
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/mm/page_io.c
	3	*
	4	* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
	5	*
	6	* Swap reorganised 29.12.95,
	7	* Asynchronous swapping added 30.12.95. Stephen Tweedie
	8	* Removed race in async swapping. 14.4.1996. Bruno Haible
	9	* Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie
	10	* Always use brw_page, life becomes simpler. 12 May 1998 Eric Biederman
	11	*/
	12
	13	#include <linux/mm.h>
	14	#include <linux/kernel_stat.h>
5a0e3ad6	15	#include <linux/gfp.h>
1da177e4 LT	16	#include <linux/pagemap.h>
	17	#include <linux/swap.h>
	18	#include <linux/bio.h>
	19	#include <linux/swapops.h>
62c230bc	20	#include <linux/buffer_head.h>
1da177e4	21	#include <linux/writeback.h>
38b5faf4	22	#include <linux/frontswap.h>
b430e9d1	23	#include <linux/blkdev.h>
e2e40f2c	24	#include <linux/uio.h>
1da177e4 LT	25	#include <asm/pgtable.h>
1da177e4 LT	26
f29ad6a9	27	static struct bio *get_swap_bio(gfp_t gfp_flags,
1da177e4 LT	28	struct page *page, bio_end_io_t end_io)
	29	{
	30	struct bio *bio;
	31
	32	bio = bio_alloc(gfp_flags, 1);
	33	if (bio) {
4f024f37 KO	34	bio->bi_iter.bi_sector = map_swap_page(page, &bio->bi_bdev);
4f024f37 KO	35	bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
1da177e4 LT	36	bio->bi_io_vec[0].bv_page = page;
	37	bio->bi_io_vec[0].bv_len = PAGE_SIZE;
	38	bio->bi_io_vec[0].bv_offset = 0;
	39	bio->bi_vcnt = 1;
4f024f37	40	bio->bi_iter.bi_size = PAGE_SIZE;
1da177e4 LT	41	bio->bi_end_io = end_io;
	42	}
	43	return bio;
	44	}
	45
1eec6702	46	void end_swap_bio_write(struct bio *bio, int err)
1da177e4 LT	47	{
	48	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
	49	struct page *page = bio->bi_io_vec[0].bv_page;
	50
6ddab3b9	51	if (!uptodate) {
1da177e4	52	SetPageError(page);
6ddab3b9 PZ	53	/*
	54	* We failed to write the page out to swap-space.
	55	* Re-dirty the page in order to avoid it being reclaimed.
	56	* Also print a dire warning that things will go BAD (tm)
	57	* very quickly.
	58	*
	59	* Also clear PG_reclaim to avoid rotate_reclaimable_page()
	60	*/
	61	set_page_dirty(page);
	62	printk(KERN_ALERT "Write-error on swap-device (%u:%u:%Lu)\n",
	63	imajor(bio->bi_bdev->bd_inode),
	64	iminor(bio->bi_bdev->bd_inode),
4f024f37	65	(unsigned long long)bio->bi_iter.bi_sector);
6ddab3b9 PZ	66	ClearPageReclaim(page);
6ddab3b9 PZ	67	}
1da177e4 LT	68	end_page_writeback(page);
1da177e4 LT	69	bio_put(bio);
1da177e4 LT	70	}
1da177e4 LT	71
6712ecf8	72	void end_swap_bio_read(struct bio *bio, int err)
1da177e4 LT	73	{
	74	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
	75	struct page *page = bio->bi_io_vec[0].bv_page;
	76
1da177e4 LT	77	if (!uptodate) {
	78	SetPageError(page);
	79	ClearPageUptodate(page);
6ddab3b9 PZ	80	printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n",
	81	imajor(bio->bi_bdev->bd_inode),
	82	iminor(bio->bi_bdev->bd_inode),
4f024f37	83	(unsigned long long)bio->bi_iter.bi_sector);
b430e9d1	84	goto out;
1da177e4	85	}
b430e9d1 MK	86
	87	SetPageUptodate(page);
	88
	89	/*
	90	* There is no guarantee that the page is in swap cache - the software
	91	* suspend code (at least) uses end_swap_bio_read() against a non-
	92	* swapcache page. So we must check PG_swapcache before proceeding with
	93	* this optimization.
	94	*/
	95	if (likely(PageSwapCache(page))) {
	96	struct swap_info_struct *sis;
	97
	98	sis = page_swap_info(page);
	99	if (sis->flags & SWP_BLKDEV) {
	100	/*
	101	* The swap subsystem performs lazy swap slot freeing,
	102	* expecting that the page will be swapped out again.
	103	* So we can avoid an unnecessary write if the page
	104	* isn't redirtied.
	105	* This is good for real swap storage because we can
	106	* reduce unnecessary I/O and enhance wear-leveling
	107	* if an SSD is used as the as swap device.
	108	* But if in-memory swap device (eg zram) is used,
	109	* this causes a duplicated copy between uncompressed
	110	* data in VM-owned memory and compressed data in
	111	* zram-owned memory. So let's free zram-owned memory
	112	* and make the VM-owned decompressed page dirty,
	113	* so the page should be swapped out somewhere again if
	114	* we again wish to reclaim it.
	115	*/
	116	struct gendisk *disk = sis->bdev->bd_disk;
	117	if (disk->fops->swap_slot_free_notify) {
	118	swp_entry_t entry;
	119	unsigned long offset;
	120
	121	entry.val = page_private(page);
	122	offset = swp_offset(entry);
	123
	124	SetPageDirty(page);
	125	disk->fops->swap_slot_free_notify(sis->bdev,
	126	offset);
	127	}
	128	}
	129	}
	130
	131	out:
1da177e4 LT	132	unlock_page(page);
1da177e4 LT	133	bio_put(bio);
1da177e4 LT	134	}
1da177e4 LT	135
a509bc1a MG	136	int generic_swapfile_activate(struct swap_info_struct *sis,
	137	struct file *swap_file,
	138	sector_t *span)
	139	{
	140	struct address_space *mapping = swap_file->f_mapping;
	141	struct inode *inode = mapping->host;
	142	unsigned blocks_per_page;
	143	unsigned long page_no;
	144	unsigned blkbits;
	145	sector_t probe_block;
	146	sector_t last_block;
	147	sector_t lowest_block = -1;
	148	sector_t highest_block = 0;
	149	int nr_extents = 0;
	150	int ret;
	151
	152	blkbits = inode->i_blkbits;
	153	blocks_per_page = PAGE_SIZE >> blkbits;
	154
	155	/*
	156	* Map all the blocks into the extent list. This code doesn't try
	157	* to be very smart.
	158	*/
	159	probe_block = 0;
	160	page_no = 0;
	161	last_block = i_size_read(inode) >> blkbits;
	162	while ((probe_block + blocks_per_page) <= last_block &&
	163	page_no < sis->max) {
	164	unsigned block_in_page;
	165	sector_t first_block;
	166
	167	first_block = bmap(inode, probe_block);
	168	if (first_block == 0)
	169	goto bad_bmap;
	170
	171	/*
	172	* It must be PAGE_SIZE aligned on-disk
	173	*/
	174	if (first_block & (blocks_per_page - 1)) {
	175	probe_block++;
	176	goto reprobe;
	177	}
	178
	179	for (block_in_page = 1; block_in_page < blocks_per_page;
	180	block_in_page++) {
	181	sector_t block;
	182
	183	block = bmap(inode, probe_block + block_in_page);
	184	if (block == 0)
	185	goto bad_bmap;
	186	if (block != first_block + block_in_page) {
	187	/* Discontiguity */
	188	probe_block++;
	189	goto reprobe;
	190	}
	191	}
	192
	193	first_block >>= (PAGE_SHIFT - blkbits);
	194	if (page_no) { /* exclude the header page */
	195	if (first_block < lowest_block)
	196	lowest_block = first_block;
	197	if (first_block > highest_block)
	198	highest_block = first_block;
	199	}
200
201	/*
202	* We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
203	*/
204	ret = add_swap_extent(sis, page_no, 1, first_block);
205	if (ret < 0)
206	goto out;
207	nr_extents += ret;
208	page_no++;
209	probe_block += blocks_per_page;
210	reprobe:
211	continue;
212	}
213	ret = nr_extents;
214	*span = 1 + highest_block - lowest_block;
215	if (page_no == 0)
216	page_no = 1; /* force Empty message */
217	sis->max = page_no;
218	sis->pages = page_no - 1;
219	sis->highest_bit = page_no - 1;
220	out:
221	return ret;
222	bad_bmap:
223	printk(KERN_ERR "swapon: swapfile has holes\n");
224	ret = -EINVAL;
225	goto out;
226	}
227
1da177e4 LT	228	/*
	229	* We may have stale swap cache pages in memory: notice
	230	* them here and get rid of the unnecessary final write.
	231	*/
	232	int swap_writepage(struct page page, struct writeback_control wbc)
	233	{
2f772e6c	234	int ret = 0;
1da177e4	235
a2c43eed	236	if (try_to_free_swap(page)) {
1da177e4 LT	237	unlock_page(page);
	238	goto out;
	239	}
165c8aed	240	if (frontswap_store(page) == 0) {
38b5faf4 DM	241	set_page_writeback(page);
	242	unlock_page(page);
	243	end_page_writeback(page);
	244	goto out;
	245	}
1eec6702	246	ret = __swap_writepage(page, wbc, end_swap_bio_write);
2f772e6c SJ	247	out:
	248	return ret;
	249	}
	250
dd6bd0d9 MW	251	static sector_t swap_page_sector(struct page *page)
	252	{
	253	return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9);
	254	}
	255
1eec6702 SJ	256	int __swap_writepage(struct page page, struct writeback_control wbc,
1eec6702 SJ	257	void (end_write_func)(struct bio , int))
2f772e6c SJ	258	{
2f772e6c SJ	259	struct bio *bio;
dd6bd0d9	260	int ret, rw = WRITE;
2f772e6c	261	struct swap_info_struct *sis = page_swap_info(page);
62c230bc MG	262
	263	if (sis->flags & SWP_FILE) {
	264	struct kiocb kiocb;
	265	struct file *swap_file = sis->swap_file;
	266	struct address_space *mapping = swap_file->f_mapping;
62a8067a AV	267	struct bio_vec bv = {
	268	.bv_page = page,
	269	.bv_len = PAGE_SIZE,
	270	.bv_offset = 0
	271	};
05afcb77	272	struct iov_iter from;
62c230bc	273
05afcb77	274	iov_iter_bvec(&from, ITER_BVEC \| WRITE, &bv, 1, PAGE_SIZE);
62c230bc MG	275	init_sync_kiocb(&kiocb, swap_file);
62c230bc MG	276	kiocb.ki_pos = page_file_offset(page);
62c230bc	277
0cdc444a	278	set_page_writeback(page);
62c230bc	279	unlock_page(page);
22c6186e	280	ret = mapping->a_ops->direct_IO(&kiocb, &from, kiocb.ki_pos);
62c230bc MG	281	if (ret == PAGE_SIZE) {
	282	count_vm_event(PSWPOUT);
	283	ret = 0;
2d30d31e	284	} else {
0cdc444a MG	285	/*
	286	* In the case of swap-over-nfs, this can be a
	287	* temporary failure if the system has limited
	288	* memory for allocating transmit buffers.
	289	* Mark the page dirty and avoid
	290	* rotate_reclaimable_page but rate-limit the
	291	* messages but do not flag PageError like
	292	* the normal direct-to-bio case as it could
	293	* be temporary.
	294	*/
2d30d31e	295	set_page_dirty(page);
0cdc444a MG	296	ClearPageReclaim(page);
	297	pr_err_ratelimited("Write error on dio swapfile (%Lu)\n",
	298	page_file_offset(page));
62c230bc	299	}
0cdc444a	300	end_page_writeback(page);
62c230bc MG	301	return ret;
	302	}
	303
dd6bd0d9 MW	304	ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
	305	if (!ret) {
	306	count_vm_event(PSWPOUT);
	307	return 0;
	308	}
	309
	310	ret = 0;
1eec6702	311	bio = get_swap_bio(GFP_NOIO, page, end_write_func);
1da177e4 LT	312	if (bio == NULL) {
	313	set_page_dirty(page);
	314	unlock_page(page);
	315	ret = -ENOMEM;
	316	goto out;
	317	}
	318	if (wbc->sync_mode == WB_SYNC_ALL)
721a9602	319	rw \|= REQ_SYNC;
f8891e5e	320	count_vm_event(PSWPOUT);
1da177e4 LT	321	set_page_writeback(page);
	322	unlock_page(page);
	323	submit_bio(rw, bio);
	324	out:
	325	return ret;
	326	}
	327
aca8bf32	328	int swap_readpage(struct page *page)
1da177e4 LT	329	{
	330	struct bio *bio;
	331	int ret = 0;
62c230bc	332	struct swap_info_struct *sis = page_swap_info(page);
1da177e4	333
309381fe SL	334	VM_BUG_ON_PAGE(!PageLocked(page), page);
309381fe SL	335	VM_BUG_ON_PAGE(PageUptodate(page), page);
165c8aed	336	if (frontswap_load(page) == 0) {
38b5faf4 DM	337	SetPageUptodate(page);
	338	unlock_page(page);
	339	goto out;
	340	}
62c230bc MG	341
	342	if (sis->flags & SWP_FILE) {
	343	struct file *swap_file = sis->swap_file;
	344	struct address_space *mapping = swap_file->f_mapping;
	345
	346	ret = mapping->a_ops->readpage(swap_file, page);
	347	if (!ret)
	348	count_vm_event(PSWPIN);
	349	return ret;
	350	}
	351
dd6bd0d9 MW	352	ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
	353	if (!ret) {
	354	count_vm_event(PSWPIN);
	355	return 0;
	356	}
	357
	358	ret = 0;
f29ad6a9	359	bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
1da177e4 LT	360	if (bio == NULL) {
	361	unlock_page(page);
	362	ret = -ENOMEM;
	363	goto out;
	364	}
f8891e5e	365	count_vm_event(PSWPIN);
1da177e4 LT	366	submit_bio(READ, bio);
	367	out:
	368	return ret;
	369	}
62c230bc MG	370
	371	int swap_set_page_dirty(struct page *page)
	372	{
	373	struct swap_info_struct *sis = page_swap_info(page);
	374
	375	if (sis->flags & SWP_FILE) {
	376	struct address_space *mapping = sis->swap_file->f_mapping;
	377	return mapping->a_ops->set_page_dirty(page);
	378	} else {
	379	return __set_page_dirty_no_writeback(page);
	380	}
	381	}