[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_end_io = end_io;

		bio_add_page(bio, page, PAGE_SIZE, 0);
		BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE);
	}
	return bio;
}

void end_swap_bio_write(struct bio *bio)
{
	struct page *page = bio->bi_io_vec[0].bv_page;

	if (bio->bi_error) {
		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);
}

static void end_swap_bio_read(struct bio *bio)
{
	struct page *page = bio->bi_io_vec[0].bv_page;

	if (bio->bi_error) {
		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,
		bio_end_io_t end_write_func)
{
	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	36	bio->bi_end_io = end_io;
6cf66b4c KO	37
	38	bio_add_page(bio, page, PAGE_SIZE, 0);
	39	BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE);
1da177e4 LT	40	}
	41	return bio;
	42	}
	43
4246a0b6	44	void end_swap_bio_write(struct bio *bio)
1da177e4	45	{
1da177e4 LT	46	struct page *page = bio->bi_io_vec[0].bv_page;
1da177e4 LT	47
4246a0b6	48	if (bio->bi_error) {
1da177e4	49	SetPageError(page);
6ddab3b9 PZ	50	/*
	51	* We failed to write the page out to swap-space.
	52	* Re-dirty the page in order to avoid it being reclaimed.
	53	* Also print a dire warning that things will go BAD (tm)
	54	* very quickly.
	55	*
	56	* Also clear PG_reclaim to avoid rotate_reclaimable_page()
	57	*/
	58	set_page_dirty(page);
	59	printk(KERN_ALERT "Write-error on swap-device (%u:%u:%Lu)\n",
	60	imajor(bio->bi_bdev->bd_inode),
	61	iminor(bio->bi_bdev->bd_inode),
4f024f37	62	(unsigned long long)bio->bi_iter.bi_sector);
6ddab3b9 PZ	63	ClearPageReclaim(page);
6ddab3b9 PZ	64	}
1da177e4 LT	65	end_page_writeback(page);
1da177e4 LT	66	bio_put(bio);
1da177e4 LT	67	}
1da177e4 LT	68
4246a0b6	69	static void end_swap_bio_read(struct bio *bio)
1da177e4	70	{
1da177e4 LT	71	struct page *page = bio->bi_io_vec[0].bv_page;
1da177e4 LT	72
4246a0b6	73	if (bio->bi_error) {
1da177e4 LT	74	SetPageError(page);
1da177e4 LT	75	ClearPageUptodate(page);
6ddab3b9 PZ	76	printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n",
	77	imajor(bio->bi_bdev->bd_inode),
	78	iminor(bio->bi_bdev->bd_inode),
4f024f37	79	(unsigned long long)bio->bi_iter.bi_sector);
b430e9d1	80	goto out;
1da177e4	81	}
b430e9d1 MK	82
	83	SetPageUptodate(page);
	84
	85	/*
	86	* There is no guarantee that the page is in swap cache - the software
	87	* suspend code (at least) uses end_swap_bio_read() against a non-
	88	* swapcache page. So we must check PG_swapcache before proceeding with
	89	* this optimization.
	90	*/
	91	if (likely(PageSwapCache(page))) {
	92	struct swap_info_struct *sis;
	93
	94	sis = page_swap_info(page);
	95	if (sis->flags & SWP_BLKDEV) {
	96	/*
	97	* The swap subsystem performs lazy swap slot freeing,
	98	* expecting that the page will be swapped out again.
	99	* So we can avoid an unnecessary write if the page
	100	* isn't redirtied.
	101	* This is good for real swap storage because we can
	102	* reduce unnecessary I/O and enhance wear-leveling
	103	* if an SSD is used as the as swap device.
	104	* But if in-memory swap device (eg zram) is used,
	105	* this causes a duplicated copy between uncompressed
	106	* data in VM-owned memory and compressed data in
	107	* zram-owned memory. So let's free zram-owned memory
	108	* and make the VM-owned decompressed page dirty,
	109	* so the page should be swapped out somewhere again if
	110	* we again wish to reclaim it.
	111	*/
	112	struct gendisk *disk = sis->bdev->bd_disk;
	113	if (disk->fops->swap_slot_free_notify) {
	114	swp_entry_t entry;
	115	unsigned long offset;
	116
	117	entry.val = page_private(page);
	118	offset = swp_offset(entry);
	119
	120	SetPageDirty(page);
	121	disk->fops->swap_slot_free_notify(sis->bdev,
	122	offset);
	123	}
	124	}
	125	}
	126
	127	out:
1da177e4 LT	128	unlock_page(page);
1da177e4 LT	129	bio_put(bio);
1da177e4 LT	130	}
1da177e4 LT	131
a509bc1a MG	132	int generic_swapfile_activate(struct swap_info_struct *sis,
	133	struct file *swap_file,
	134	sector_t *span)
	135	{
	136	struct address_space *mapping = swap_file->f_mapping;
	137	struct inode *inode = mapping->host;
	138	unsigned blocks_per_page;
	139	unsigned long page_no;
	140	unsigned blkbits;
	141	sector_t probe_block;
	142	sector_t last_block;
	143	sector_t lowest_block = -1;
	144	sector_t highest_block = 0;
	145	int nr_extents = 0;
	146	int ret;
	147
	148	blkbits = inode->i_blkbits;
	149	blocks_per_page = PAGE_SIZE >> blkbits;
	150
	151	/*
	152	* Map all the blocks into the extent list. This code doesn't try
	153	* to be very smart.
	154	*/
	155	probe_block = 0;
	156	page_no = 0;
	157	last_block = i_size_read(inode) >> blkbits;
	158	while ((probe_block + blocks_per_page) <= last_block &&
	159	page_no < sis->max) {
	160	unsigned block_in_page;
	161	sector_t first_block;
	162
	163	first_block = bmap(inode, probe_block);
	164	if (first_block == 0)
	165	goto bad_bmap;
	166
	167	/*
	168	* It must be PAGE_SIZE aligned on-disk
	169	*/
	170	if (first_block & (blocks_per_page - 1)) {
	171	probe_block++;
	172	goto reprobe;
	173	}
	174
	175	for (block_in_page = 1; block_in_page < blocks_per_page;
	176	block_in_page++) {
	177	sector_t block;
	178
	179	block = bmap(inode, probe_block + block_in_page);
	180	if (block == 0)
	181	goto bad_bmap;
	182	if (block != first_block + block_in_page) {
	183	/* Discontiguity */
	184	probe_block++;
	185	goto reprobe;
	186	}
	187	}
	188
	189	first_block >>= (PAGE_SHIFT - blkbits);
	190	if (page_no) { /* exclude the header page */
	191	if (first_block < lowest_block)
	192	lowest_block = first_block;
	193	if (first_block > highest_block)
	194	highest_block = first_block;
	195	}
196
197	/*
198	* We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
199	*/
200	ret = add_swap_extent(sis, page_no, 1, first_block);
201	if (ret < 0)
202	goto out;
203	nr_extents += ret;
204	page_no++;
205	probe_block += blocks_per_page;
206	reprobe:
207	continue;
208	}
209	ret = nr_extents;
210	*span = 1 + highest_block - lowest_block;
211	if (page_no == 0)
212	page_no = 1; /* force Empty message */
213	sis->max = page_no;
214	sis->pages = page_no - 1;
215	sis->highest_bit = page_no - 1;
216	out:
217	return ret;
218	bad_bmap:
219	printk(KERN_ERR "swapon: swapfile has holes\n");
220	ret = -EINVAL;
221	goto out;
222	}
223
1da177e4 LT	224	/*
	225	* We may have stale swap cache pages in memory: notice
	226	* them here and get rid of the unnecessary final write.
	227	*/
	228	int swap_writepage(struct page page, struct writeback_control wbc)
	229	{
2f772e6c	230	int ret = 0;
1da177e4	231
a2c43eed	232	if (try_to_free_swap(page)) {
1da177e4 LT	233	unlock_page(page);
	234	goto out;
	235	}
165c8aed	236	if (frontswap_store(page) == 0) {
38b5faf4 DM	237	set_page_writeback(page);
	238	unlock_page(page);
	239	end_page_writeback(page);
	240	goto out;
	241	}
1eec6702	242	ret = __swap_writepage(page, wbc, end_swap_bio_write);
2f772e6c SJ	243	out:
	244	return ret;
	245	}
	246
dd6bd0d9 MW	247	static sector_t swap_page_sector(struct page *page)
	248	{
	249	return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9);
	250	}
	251
1eec6702	252	int __swap_writepage(struct page page, struct writeback_control wbc,
4246a0b6	253	bio_end_io_t end_write_func)
2f772e6c SJ	254	{
2f772e6c SJ	255	struct bio *bio;
dd6bd0d9	256	int ret, rw = WRITE;
2f772e6c	257	struct swap_info_struct *sis = page_swap_info(page);
62c230bc MG	258
	259	if (sis->flags & SWP_FILE) {
	260	struct kiocb kiocb;
	261	struct file *swap_file = sis->swap_file;
	262	struct address_space *mapping = swap_file->f_mapping;
62a8067a AV	263	struct bio_vec bv = {
	264	.bv_page = page,
	265	.bv_len = PAGE_SIZE,
	266	.bv_offset = 0
	267	};
05afcb77	268	struct iov_iter from;
62c230bc	269
05afcb77	270	iov_iter_bvec(&from, ITER_BVEC \| WRITE, &bv, 1, PAGE_SIZE);
62c230bc MG	271	init_sync_kiocb(&kiocb, swap_file);
62c230bc MG	272	kiocb.ki_pos = page_file_offset(page);
62c230bc	273
0cdc444a	274	set_page_writeback(page);
62c230bc	275	unlock_page(page);
22c6186e	276	ret = mapping->a_ops->direct_IO(&kiocb, &from, kiocb.ki_pos);
62c230bc MG	277	if (ret == PAGE_SIZE) {
	278	count_vm_event(PSWPOUT);
	279	ret = 0;
2d30d31e	280	} else {
0cdc444a MG	281	/*
	282	* In the case of swap-over-nfs, this can be a
	283	* temporary failure if the system has limited
	284	* memory for allocating transmit buffers.
	285	* Mark the page dirty and avoid
	286	* rotate_reclaimable_page but rate-limit the
	287	* messages but do not flag PageError like
	288	* the normal direct-to-bio case as it could
	289	* be temporary.
	290	*/
2d30d31e	291	set_page_dirty(page);
0cdc444a MG	292	ClearPageReclaim(page);
	293	pr_err_ratelimited("Write error on dio swapfile (%Lu)\n",
	294	page_file_offset(page));
62c230bc	295	}
0cdc444a	296	end_page_writeback(page);
62c230bc MG	297	return ret;
	298	}
	299
dd6bd0d9 MW	300	ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
	301	if (!ret) {
	302	count_vm_event(PSWPOUT);
	303	return 0;
	304	}
	305
	306	ret = 0;
1eec6702	307	bio = get_swap_bio(GFP_NOIO, page, end_write_func);
1da177e4 LT	308	if (bio == NULL) {
	309	set_page_dirty(page);
	310	unlock_page(page);
	311	ret = -ENOMEM;
	312	goto out;
	313	}
	314	if (wbc->sync_mode == WB_SYNC_ALL)
721a9602	315	rw \|= REQ_SYNC;
f8891e5e	316	count_vm_event(PSWPOUT);
1da177e4 LT	317	set_page_writeback(page);
	318	unlock_page(page);
	319	submit_bio(rw, bio);
	320	out:
	321	return ret;
	322	}
	323
aca8bf32	324	int swap_readpage(struct page *page)
1da177e4 LT	325	{
	326	struct bio *bio;
	327	int ret = 0;
62c230bc	328	struct swap_info_struct *sis = page_swap_info(page);
1da177e4	329
309381fe SL	330	VM_BUG_ON_PAGE(!PageLocked(page), page);
309381fe SL	331	VM_BUG_ON_PAGE(PageUptodate(page), page);
165c8aed	332	if (frontswap_load(page) == 0) {
38b5faf4 DM	333	SetPageUptodate(page);
	334	unlock_page(page);
	335	goto out;
	336	}
62c230bc MG	337
	338	if (sis->flags & SWP_FILE) {
	339	struct file *swap_file = sis->swap_file;
	340	struct address_space *mapping = swap_file->f_mapping;
	341
	342	ret = mapping->a_ops->readpage(swap_file, page);
	343	if (!ret)
	344	count_vm_event(PSWPIN);
	345	return ret;
	346	}
	347
dd6bd0d9 MW	348	ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
	349	if (!ret) {
	350	count_vm_event(PSWPIN);
	351	return 0;
	352	}
	353
	354	ret = 0;
f29ad6a9	355	bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
1da177e4 LT	356	if (bio == NULL) {
	357	unlock_page(page);
	358	ret = -ENOMEM;
	359	goto out;
	360	}
f8891e5e	361	count_vm_event(PSWPIN);
1da177e4 LT	362	submit_bio(READ, bio);
	363	out:
	364	return ret;
	365	}
62c230bc MG	366
	367	int swap_set_page_dirty(struct page *page)
	368	{
	369	struct swap_info_struct *sis = page_swap_info(page);
	370
	371	if (sis->flags & SWP_FILE) {
	372	struct address_space *mapping = sis->swap_file->f_mapping;
	373	return mapping->a_ops->set_page_dirty(page);
	374	} else {
	375	return __set_page_dirty_no_writeback(page);
	376	}
	377	}