[mirror_ubuntu-zesty-kernel.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)
{
	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 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
4246a0b6	46	void end_swap_bio_write(struct bio *bio)
1da177e4	47	{
1da177e4 LT	48	struct page *page = bio->bi_io_vec[0].bv_page;
1da177e4 LT	49
4246a0b6	50	if (bio->bi_error) {
1da177e4	51	SetPageError(page);
6ddab3b9 PZ	52	/*
	53	* We failed to write the page out to swap-space.
	54	* Re-dirty the page in order to avoid it being reclaimed.
	55	* Also print a dire warning that things will go BAD (tm)
	56	* very quickly.
	57	*
	58	* Also clear PG_reclaim to avoid rotate_reclaimable_page()
	59	*/
	60	set_page_dirty(page);
	61	printk(KERN_ALERT "Write-error on swap-device (%u:%u:%Lu)\n",
	62	imajor(bio->bi_bdev->bd_inode),
	63	iminor(bio->bi_bdev->bd_inode),
4f024f37	64	(unsigned long long)bio->bi_iter.bi_sector);
6ddab3b9 PZ	65	ClearPageReclaim(page);
6ddab3b9 PZ	66	}
1da177e4 LT	67	end_page_writeback(page);
1da177e4 LT	68	bio_put(bio);
1da177e4 LT	69	}
1da177e4 LT	70
4246a0b6	71	static void end_swap_bio_read(struct bio *bio)
1da177e4	72	{
1da177e4 LT	73	struct page *page = bio->bi_io_vec[0].bv_page;
1da177e4 LT	74
4246a0b6	75	if (bio->bi_error) {
1da177e4 LT	76	SetPageError(page);
1da177e4 LT	77	ClearPageUptodate(page);
6ddab3b9 PZ	78	printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n",
	79	imajor(bio->bi_bdev->bd_inode),
	80	iminor(bio->bi_bdev->bd_inode),
4f024f37	81	(unsigned long long)bio->bi_iter.bi_sector);
b430e9d1	82	goto out;
1da177e4	83	}
b430e9d1 MK	84
	85	SetPageUptodate(page);
	86
	87	/*
	88	* There is no guarantee that the page is in swap cache - the software
	89	* suspend code (at least) uses end_swap_bio_read() against a non-
	90	* swapcache page. So we must check PG_swapcache before proceeding with
	91	* this optimization.
	92	*/
	93	if (likely(PageSwapCache(page))) {
	94	struct swap_info_struct *sis;
	95
	96	sis = page_swap_info(page);
	97	if (sis->flags & SWP_BLKDEV) {
	98	/*
	99	* The swap subsystem performs lazy swap slot freeing,
	100	* expecting that the page will be swapped out again.
	101	* So we can avoid an unnecessary write if the page
	102	* isn't redirtied.
	103	* This is good for real swap storage because we can
	104	* reduce unnecessary I/O and enhance wear-leveling
	105	* if an SSD is used as the as swap device.
	106	* But if in-memory swap device (eg zram) is used,
	107	* this causes a duplicated copy between uncompressed
	108	* data in VM-owned memory and compressed data in
	109	* zram-owned memory. So let's free zram-owned memory
	110	* and make the VM-owned decompressed page dirty,
	111	* so the page should be swapped out somewhere again if
	112	* we again wish to reclaim it.
	113	*/
	114	struct gendisk *disk = sis->bdev->bd_disk;
	115	if (disk->fops->swap_slot_free_notify) {
	116	swp_entry_t entry;
	117	unsigned long offset;
	118
	119	entry.val = page_private(page);
	120	offset = swp_offset(entry);
	121
	122	SetPageDirty(page);
	123	disk->fops->swap_slot_free_notify(sis->bdev,
	124	offset);
	125	}
	126	}
	127	}
	128
	129	out:
1da177e4 LT	130	unlock_page(page);
1da177e4 LT	131	bio_put(bio);
1da177e4 LT	132	}
1da177e4 LT	133
a509bc1a MG	134	int generic_swapfile_activate(struct swap_info_struct *sis,
	135	struct file *swap_file,
	136	sector_t *span)
	137	{
	138	struct address_space *mapping = swap_file->f_mapping;
	139	struct inode *inode = mapping->host;
	140	unsigned blocks_per_page;
	141	unsigned long page_no;
	142	unsigned blkbits;
	143	sector_t probe_block;
	144	sector_t last_block;
	145	sector_t lowest_block = -1;
	146	sector_t highest_block = 0;
	147	int nr_extents = 0;
	148	int ret;
	149
	150	blkbits = inode->i_blkbits;
	151	blocks_per_page = PAGE_SIZE >> blkbits;
	152
	153	/*
	154	* Map all the blocks into the extent list. This code doesn't try
	155	* to be very smart.
	156	*/
	157	probe_block = 0;
	158	page_no = 0;
	159	last_block = i_size_read(inode) >> blkbits;
	160	while ((probe_block + blocks_per_page) <= last_block &&
	161	page_no < sis->max) {
	162	unsigned block_in_page;
	163	sector_t first_block;
	164
	165	first_block = bmap(inode, probe_block);
	166	if (first_block == 0)
	167	goto bad_bmap;
	168
	169	/*
	170	* It must be PAGE_SIZE aligned on-disk
	171	*/
	172	if (first_block & (blocks_per_page - 1)) {
	173	probe_block++;
	174	goto reprobe;
	175	}
	176
	177	for (block_in_page = 1; block_in_page < blocks_per_page;
	178	block_in_page++) {
	179	sector_t block;
	180
	181	block = bmap(inode, probe_block + block_in_page);
	182	if (block == 0)
	183	goto bad_bmap;
	184	if (block != first_block + block_in_page) {
	185	/* Discontiguity */
	186	probe_block++;
	187	goto reprobe;
	188	}
	189	}
	190
	191	first_block >>= (PAGE_SHIFT - blkbits);
	192	if (page_no) { /* exclude the header page */
	193	if (first_block < lowest_block)
	194	lowest_block = first_block;
	195	if (first_block > highest_block)
	196	highest_block = first_block;
	197	}
198
199	/*
200	* We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
201	*/
202	ret = add_swap_extent(sis, page_no, 1, first_block);
203	if (ret < 0)
204	goto out;
205	nr_extents += ret;
206	page_no++;
207	probe_block += blocks_per_page;
208	reprobe:
209	continue;
210	}
211	ret = nr_extents;
212	*span = 1 + highest_block - lowest_block;
213	if (page_no == 0)
214	page_no = 1; /* force Empty message */
215	sis->max = page_no;
216	sis->pages = page_no - 1;
217	sis->highest_bit = page_no - 1;
218	out:
219	return ret;
220	bad_bmap:
221	printk(KERN_ERR "swapon: swapfile has holes\n");
222	ret = -EINVAL;
223	goto out;
224	}
225
1da177e4 LT	226	/*
	227	* We may have stale swap cache pages in memory: notice
	228	* them here and get rid of the unnecessary final write.
	229	*/
	230	int swap_writepage(struct page page, struct writeback_control wbc)
	231	{
2f772e6c	232	int ret = 0;
1da177e4	233
a2c43eed	234	if (try_to_free_swap(page)) {
1da177e4 LT	235	unlock_page(page);
	236	goto out;
	237	}
165c8aed	238	if (frontswap_store(page) == 0) {
38b5faf4 DM	239	set_page_writeback(page);
	240	unlock_page(page);
	241	end_page_writeback(page);
	242	goto out;
	243	}
1eec6702	244	ret = __swap_writepage(page, wbc, end_swap_bio_write);
2f772e6c SJ	245	out:
	246	return ret;
	247	}
	248
dd6bd0d9 MW	249	static sector_t swap_page_sector(struct page *page)
	250	{
	251	return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9);
	252	}
	253
1eec6702	254	int __swap_writepage(struct page page, struct writeback_control wbc,
4246a0b6	255	bio_end_io_t end_write_func)
2f772e6c SJ	256	{
2f772e6c SJ	257	struct bio *bio;
dd6bd0d9	258	int ret, rw = WRITE;
2f772e6c	259	struct swap_info_struct *sis = page_swap_info(page);
62c230bc MG	260
	261	if (sis->flags & SWP_FILE) {
	262	struct kiocb kiocb;
	263	struct file *swap_file = sis->swap_file;
	264	struct address_space *mapping = swap_file->f_mapping;
62a8067a AV	265	struct bio_vec bv = {
	266	.bv_page = page,
	267	.bv_len = PAGE_SIZE,
	268	.bv_offset = 0
	269	};
05afcb77	270	struct iov_iter from;
62c230bc	271
05afcb77	272	iov_iter_bvec(&from, ITER_BVEC \| WRITE, &bv, 1, PAGE_SIZE);
62c230bc MG	273	init_sync_kiocb(&kiocb, swap_file);
62c230bc MG	274	kiocb.ki_pos = page_file_offset(page);
62c230bc	275
0cdc444a	276	set_page_writeback(page);
62c230bc	277	unlock_page(page);
22c6186e	278	ret = mapping->a_ops->direct_IO(&kiocb, &from, kiocb.ki_pos);
62c230bc MG	279	if (ret == PAGE_SIZE) {
	280	count_vm_event(PSWPOUT);
	281	ret = 0;
2d30d31e	282	} else {
0cdc444a MG	283	/*
	284	* In the case of swap-over-nfs, this can be a
	285	* temporary failure if the system has limited
	286	* memory for allocating transmit buffers.
	287	* Mark the page dirty and avoid
	288	* rotate_reclaimable_page but rate-limit the
	289	* messages but do not flag PageError like
	290	* the normal direct-to-bio case as it could
	291	* be temporary.
	292	*/
2d30d31e	293	set_page_dirty(page);
0cdc444a MG	294	ClearPageReclaim(page);
	295	pr_err_ratelimited("Write error on dio swapfile (%Lu)\n",
	296	page_file_offset(page));
62c230bc	297	}
0cdc444a	298	end_page_writeback(page);
62c230bc MG	299	return ret;
	300	}
	301
dd6bd0d9 MW	302	ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
	303	if (!ret) {
	304	count_vm_event(PSWPOUT);
	305	return 0;
	306	}
	307
	308	ret = 0;
1eec6702	309	bio = get_swap_bio(GFP_NOIO, page, end_write_func);
1da177e4 LT	310	if (bio == NULL) {
	311	set_page_dirty(page);
	312	unlock_page(page);
	313	ret = -ENOMEM;
	314	goto out;
	315	}
	316	if (wbc->sync_mode == WB_SYNC_ALL)
721a9602	317	rw \|= REQ_SYNC;
f8891e5e	318	count_vm_event(PSWPOUT);
1da177e4 LT	319	set_page_writeback(page);
	320	unlock_page(page);
	321	submit_bio(rw, bio);
	322	out:
	323	return ret;
	324	}
	325
aca8bf32	326	int swap_readpage(struct page *page)
1da177e4 LT	327	{
	328	struct bio *bio;
	329	int ret = 0;
62c230bc	330	struct swap_info_struct *sis = page_swap_info(page);
1da177e4	331
309381fe SL	332	VM_BUG_ON_PAGE(!PageLocked(page), page);
309381fe SL	333	VM_BUG_ON_PAGE(PageUptodate(page), page);
165c8aed	334	if (frontswap_load(page) == 0) {
38b5faf4 DM	335	SetPageUptodate(page);
	336	unlock_page(page);
	337	goto out;
	338	}
62c230bc MG	339
	340	if (sis->flags & SWP_FILE) {
	341	struct file *swap_file = sis->swap_file;
	342	struct address_space *mapping = swap_file->f_mapping;
	343
	344	ret = mapping->a_ops->readpage(swap_file, page);
	345	if (!ret)
	346	count_vm_event(PSWPIN);
	347	return ret;
	348	}
	349
dd6bd0d9 MW	350	ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
	351	if (!ret) {
	352	count_vm_event(PSWPIN);
	353	return 0;
	354	}
	355
	356	ret = 0;
f29ad6a9	357	bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
1da177e4 LT	358	if (bio == NULL) {
	359	unlock_page(page);
	360	ret = -ENOMEM;
	361	goto out;
	362	}
f8891e5e	363	count_vm_event(PSWPIN);
1da177e4 LT	364	submit_bio(READ, bio);
	365	out:
	366	return ret;
	367	}
62c230bc MG	368
	369	int swap_set_page_dirty(struct page *page)
	370	{
	371	struct swap_info_struct *sis = page_swap_info(page);
	372
	373	if (sis->flags & SWP_FILE) {
	374	struct address_space *mapping = sis->swap_file->f_mapping;
	375	return mapping->a_ops->set_page_dirty(page);
	376	} else {
	377	return __set_page_dirty_no_writeback(page);
	378	}
	379	}