[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_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);
		pr_alert("Write-error on swap-device (%u:%u:%llu)\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 swap_slot_free_notify(struct page *page)
{
	struct swap_info_struct *sis;
	struct gendisk *disk;

	/*
	 * 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 (unlikely(!PageSwapCache(page)))
		return;

	sis = page_swap_info(page);
	if (!(sis->flags & SWP_BLKDEV))
		return;

	/*
	 * 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.
	 */
	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);
	}
}

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);
		pr_alert("Read-error on swap-device (%u:%u:%llu)\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);
	swap_slot_free_notify(page);
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:
	pr_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_SHIFT - 9);
}

int __swap_writepage(struct page *page, struct writeback_control *wbc,
		bio_end_io_t end_write_func)
{
	struct bio *bio;
	int ret;
	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);
		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 (%llu)\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;
	}
	bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
	if (wbc->sync_mode == WB_SYNC_ALL)
		bio->bi_rw |= REQ_SYNC;
	count_vm_event(PSWPOUT);
	set_page_writeback(page);
	unlock_page(page);
	submit_bio(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) {
		if (trylock_page(page)) {
			swap_slot_free_notify(page);
			unlock_page(page);
		}

		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;
	}
	bio_set_op_attrs(bio, REQ_OP_READ, 0);
	count_vm_event(PSWPIN);
	submit_bio(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);
1170532b JP	59	pr_alert("Write-error on swap-device (%u:%u:%llu)\n",
	60	imajor(bio->bi_bdev->bd_inode),
	61	iminor(bio->bi_bdev->bd_inode),
	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
3f2b1a04 MK	69	static void swap_slot_free_notify(struct page *page)
	70	{
	71	struct swap_info_struct *sis;
	72	struct gendisk *disk;
	73
	74	/*
	75	* There is no guarantee that the page is in swap cache - the software
	76	* suspend code (at least) uses end_swap_bio_read() against a non-
	77	* swapcache page. So we must check PG_swapcache before proceeding with
	78	* this optimization.
	79	*/
	80	if (unlikely(!PageSwapCache(page)))
	81	return;
	82
	83	sis = page_swap_info(page);
	84	if (!(sis->flags & SWP_BLKDEV))
	85	return;
	86
	87	/*
	88	* The swap subsystem performs lazy swap slot freeing,
	89	* expecting that the page will be swapped out again.
	90	* So we can avoid an unnecessary write if the page
	91	* isn't redirtied.
	92	* This is good for real swap storage because we can
	93	* reduce unnecessary I/O and enhance wear-leveling
	94	* if an SSD is used as the as swap device.
	95	* But if in-memory swap device (eg zram) is used,
	96	* this causes a duplicated copy between uncompressed
	97	* data in VM-owned memory and compressed data in
	98	* zram-owned memory. So let's free zram-owned memory
	99	* and make the VM-owned decompressed page dirty,
	100	* so the page should be swapped out somewhere again if
	101	* we again wish to reclaim it.
	102	*/
	103	disk = sis->bdev->bd_disk;
	104	if (disk->fops->swap_slot_free_notify) {
	105	swp_entry_t entry;
	106	unsigned long offset;
	107
	108	entry.val = page_private(page);
	109	offset = swp_offset(entry);
	110
	111	SetPageDirty(page);
	112	disk->fops->swap_slot_free_notify(sis->bdev,
	113	offset);
	114	}
	115	}
	116
4246a0b6	117	static void end_swap_bio_read(struct bio *bio)
1da177e4	118	{
1da177e4 LT	119	struct page *page = bio->bi_io_vec[0].bv_page;
1da177e4 LT	120
4246a0b6	121	if (bio->bi_error) {
1da177e4 LT	122	SetPageError(page);
1da177e4 LT	123	ClearPageUptodate(page);
1170532b JP	124	pr_alert("Read-error on swap-device (%u:%u:%llu)\n",
	125	imajor(bio->bi_bdev->bd_inode),
	126	iminor(bio->bi_bdev->bd_inode),
	127	(unsigned long long)bio->bi_iter.bi_sector);
b430e9d1	128	goto out;
1da177e4	129	}
b430e9d1 MK	130
b430e9d1 MK	131	SetPageUptodate(page);
3f2b1a04	132	swap_slot_free_notify(page);
b430e9d1	133	out:
1da177e4 LT	134	unlock_page(page);
1da177e4 LT	135	bio_put(bio);
1da177e4 LT	136	}
1da177e4 LT	137
a509bc1a MG	138	int generic_swapfile_activate(struct swap_info_struct *sis,
	139	struct file *swap_file,
	140	sector_t *span)
	141	{
	142	struct address_space *mapping = swap_file->f_mapping;
	143	struct inode *inode = mapping->host;
	144	unsigned blocks_per_page;
	145	unsigned long page_no;
	146	unsigned blkbits;
	147	sector_t probe_block;
	148	sector_t last_block;
	149	sector_t lowest_block = -1;
	150	sector_t highest_block = 0;
	151	int nr_extents = 0;
	152	int ret;
	153
	154	blkbits = inode->i_blkbits;
	155	blocks_per_page = PAGE_SIZE >> blkbits;
	156
	157	/*
	158	* Map all the blocks into the extent list. This code doesn't try
	159	* to be very smart.
	160	*/
	161	probe_block = 0;
	162	page_no = 0;
	163	last_block = i_size_read(inode) >> blkbits;
	164	while ((probe_block + blocks_per_page) <= last_block &&
	165	page_no < sis->max) {
	166	unsigned block_in_page;
	167	sector_t first_block;
	168
	169	first_block = bmap(inode, probe_block);
	170	if (first_block == 0)
	171	goto bad_bmap;
	172
	173	/*
	174	* It must be PAGE_SIZE aligned on-disk
	175	*/
	176	if (first_block & (blocks_per_page - 1)) {
	177	probe_block++;
	178	goto reprobe;
	179	}
	180
	181	for (block_in_page = 1; block_in_page < blocks_per_page;
	182	block_in_page++) {
	183	sector_t block;
	184
	185	block = bmap(inode, probe_block + block_in_page);
	186	if (block == 0)
	187	goto bad_bmap;
	188	if (block != first_block + block_in_page) {
	189	/* Discontiguity */
	190	probe_block++;
	191	goto reprobe;
	192	}
	193	}
	194
	195	first_block >>= (PAGE_SHIFT - blkbits);
	196	if (page_no) { /* exclude the header page */
	197	if (first_block < lowest_block)
	198	lowest_block = first_block;
	199	if (first_block > highest_block)
	200	highest_block = first_block;
	201	}
202
203	/*
204	* We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
205	*/
206	ret = add_swap_extent(sis, page_no, 1, first_block);
207	if (ret < 0)
208	goto out;
209	nr_extents += ret;
210	page_no++;
211	probe_block += blocks_per_page;
212	reprobe:
213	continue;
214	}
215	ret = nr_extents;
216	*span = 1 + highest_block - lowest_block;
217	if (page_no == 0)
218	page_no = 1; /* force Empty message */
219	sis->max = page_no;
220	sis->pages = page_no - 1;
221	sis->highest_bit = page_no - 1;
222	out:
223	return ret;
224	bad_bmap:
1170532b	225	pr_err("swapon: swapfile has holes\n");
a509bc1a MG	226	ret = -EINVAL;
	227	goto out;
	228	}
	229
1da177e4 LT	230	/*
	231	* We may have stale swap cache pages in memory: notice
	232	* them here and get rid of the unnecessary final write.
	233	*/
	234	int swap_writepage(struct page page, struct writeback_control wbc)
	235	{
2f772e6c	236	int ret = 0;
1da177e4	237
a2c43eed	238	if (try_to_free_swap(page)) {
1da177e4 LT	239	unlock_page(page);
	240	goto out;
	241	}
165c8aed	242	if (frontswap_store(page) == 0) {
38b5faf4 DM	243	set_page_writeback(page);
	244	unlock_page(page);
	245	end_page_writeback(page);
	246	goto out;
	247	}
1eec6702	248	ret = __swap_writepage(page, wbc, end_swap_bio_write);
2f772e6c SJ	249	out:
	250	return ret;
	251	}
	252
dd6bd0d9 MW	253	static sector_t swap_page_sector(struct page *page)
dd6bd0d9 MW	254	{
09cbfeaf	255	return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9);
dd6bd0d9 MW	256	}
dd6bd0d9 MW	257
1eec6702	258	int __swap_writepage(struct page page, struct writeback_control wbc,
4246a0b6	259	bio_end_io_t end_write_func)
2f772e6c SJ	260	{
2f772e6c SJ	261	struct bio *bio;
4e49ea4a	262	int ret;
2f772e6c	263	struct swap_info_struct *sis = page_swap_info(page);
62c230bc MG	264
	265	if (sis->flags & SWP_FILE) {
	266	struct kiocb kiocb;
	267	struct file *swap_file = sis->swap_file;
	268	struct address_space *mapping = swap_file->f_mapping;
62a8067a AV	269	struct bio_vec bv = {
	270	.bv_page = page,
	271	.bv_len = PAGE_SIZE,
	272	.bv_offset = 0
	273	};
05afcb77	274	struct iov_iter from;
62c230bc	275
05afcb77	276	iov_iter_bvec(&from, ITER_BVEC \| WRITE, &bv, 1, PAGE_SIZE);
62c230bc MG	277	init_sync_kiocb(&kiocb, swap_file);
62c230bc MG	278	kiocb.ki_pos = page_file_offset(page);
62c230bc	279
0cdc444a	280	set_page_writeback(page);
62c230bc	281	unlock_page(page);
c8b8e32d	282	ret = mapping->a_ops->direct_IO(&kiocb, &from);
62c230bc MG	283	if (ret == PAGE_SIZE) {
	284	count_vm_event(PSWPOUT);
	285	ret = 0;
2d30d31e	286	} else {
0cdc444a MG	287	/*
	288	* In the case of swap-over-nfs, this can be a
	289	* temporary failure if the system has limited
	290	* memory for allocating transmit buffers.
	291	* Mark the page dirty and avoid
	292	* rotate_reclaimable_page but rate-limit the
	293	* messages but do not flag PageError like
	294	* the normal direct-to-bio case as it could
	295	* be temporary.
	296	*/
2d30d31e	297	set_page_dirty(page);
0cdc444a	298	ClearPageReclaim(page);
1170532b JP	299	pr_err_ratelimited("Write error on dio swapfile (%llu)\n",
1170532b JP	300	page_file_offset(page));
62c230bc	301	}
0cdc444a	302	end_page_writeback(page);
62c230bc MG	303	return ret;
	304	}
	305
dd6bd0d9 MW	306	ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
	307	if (!ret) {
	308	count_vm_event(PSWPOUT);
	309	return 0;
	310	}
	311
	312	ret = 0;
1eec6702	313	bio = get_swap_bio(GFP_NOIO, page, end_write_func);
1da177e4 LT	314	if (bio == NULL) {
	315	set_page_dirty(page);
	316	unlock_page(page);
	317	ret = -ENOMEM;
	318	goto out;
	319	}
95fe6c1a	320	bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
1da177e4	321	if (wbc->sync_mode == WB_SYNC_ALL)
4e49ea4a	322	bio->bi_rw \|= REQ_SYNC;
f8891e5e	323	count_vm_event(PSWPOUT);
1da177e4 LT	324	set_page_writeback(page);
1da177e4 LT	325	unlock_page(page);
4e49ea4a	326	submit_bio(bio);
1da177e4 LT	327	out:
	328	return ret;
	329	}
	330
aca8bf32	331	int swap_readpage(struct page *page)
1da177e4 LT	332	{
	333	struct bio *bio;
	334	int ret = 0;
62c230bc	335	struct swap_info_struct *sis = page_swap_info(page);
1da177e4	336
309381fe SL	337	VM_BUG_ON_PAGE(!PageLocked(page), page);
309381fe SL	338	VM_BUG_ON_PAGE(PageUptodate(page), page);
165c8aed	339	if (frontswap_load(page) == 0) {
38b5faf4 DM	340	SetPageUptodate(page);
	341	unlock_page(page);
	342	goto out;
	343	}
62c230bc MG	344
	345	if (sis->flags & SWP_FILE) {
	346	struct file *swap_file = sis->swap_file;
	347	struct address_space *mapping = swap_file->f_mapping;
	348
	349	ret = mapping->a_ops->readpage(swap_file, page);
	350	if (!ret)
	351	count_vm_event(PSWPIN);
	352	return ret;
	353	}
	354
dd6bd0d9 MW	355	ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
dd6bd0d9 MW	356	if (!ret) {
b06bad17 MK	357	if (trylock_page(page)) {
	358	swap_slot_free_notify(page);
	359	unlock_page(page);
	360	}
	361
dd6bd0d9 MW	362	count_vm_event(PSWPIN);
	363	return 0;
	364	}
	365
	366	ret = 0;
f29ad6a9	367	bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
1da177e4 LT	368	if (bio == NULL) {
	369	unlock_page(page);
	370	ret = -ENOMEM;
	371	goto out;
	372	}
95fe6c1a	373	bio_set_op_attrs(bio, REQ_OP_READ, 0);
f8891e5e	374	count_vm_event(PSWPIN);
4e49ea4a	375	submit_bio(bio);
1da177e4 LT	376	out:
	377	return ret;
	378	}
62c230bc MG	379
	380	int swap_set_page_dirty(struct page *page)
	381	{
	382	struct swap_info_struct *sis = page_swap_info(page);
	383
	384	if (sis->flags & SWP_FILE) {
	385	struct address_space *mapping = sis->swap_file->f_mapping;
	386	return mapping->a_ops->set_page_dirty(page);
	387	} else {
	388	return __set_page_dirty_no_writeback(page);
	389	}
	390	}