[mirror_ubuntu-bionic-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_status) {
		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;
	struct task_struct *waiter = bio->bi_private;

	if (bio->bi_status) {
		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);
	WRITE_ONCE(bio->bi_private, NULL);
	bio_put(bio);
	wake_up_process(waiter);
}

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;

		cond_resched();

		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);

	VM_BUG_ON_PAGE(!PageSwapCache(page), 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->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
	count_vm_event(PSWPOUT);
	set_page_writeback(page);
	unlock_page(page);
	submit_bio(bio);
out:
	return ret;
}

int swap_readpage(struct page *page, bool do_poll)
{
	struct bio *bio;
	int ret = 0;
	struct swap_info_struct *sis = page_swap_info(page);
	blk_qc_t qc;
	struct block_device *bdev;

	VM_BUG_ON_PAGE(!PageSwapCache(page), 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;
	}
	bdev = bio->bi_bdev;
	bio->bi_private = current;
	bio_set_op_attrs(bio, REQ_OP_READ, 0);
	count_vm_event(PSWPIN);
	bio_get(bio);
	qc = submit_bio(bio);
	while (do_poll) {
		set_current_state(TASK_UNINTERRUPTIBLE);
		if (!READ_ONCE(bio->bi_private))
			break;

		if (!blk_mq_poll(bdev_get_queue(bdev), qc))
			break;
	}
	__set_current_state(TASK_RUNNING);
	bio_put(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;

		VM_BUG_ON_PAGE(!PageSwapCache(page), page);
		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
4e4cbee9	48	if (bio->bi_status) {
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	119	struct page *page = bio->bi_io_vec[0].bv_page;
23955622	120	struct task_struct *waiter = bio->bi_private;
1da177e4	121
4e4cbee9	122	if (bio->bi_status) {
1da177e4 LT	123	SetPageError(page);
1da177e4 LT	124	ClearPageUptodate(page);
1170532b JP	125	pr_alert("Read-error on swap-device (%u:%u:%llu)\n",
	126	imajor(bio->bi_bdev->bd_inode),
	127	iminor(bio->bi_bdev->bd_inode),
	128	(unsigned long long)bio->bi_iter.bi_sector);
b430e9d1	129	goto out;
1da177e4	130	}
b430e9d1 MK	131
b430e9d1 MK	132	SetPageUptodate(page);
3f2b1a04	133	swap_slot_free_notify(page);
b430e9d1	134	out:
1da177e4	135	unlock_page(page);
23955622	136	WRITE_ONCE(bio->bi_private, NULL);
1da177e4	137	bio_put(bio);
23955622	138	wake_up_process(waiter);
1da177e4 LT	139	}
1da177e4 LT	140
a509bc1a MG	141	int generic_swapfile_activate(struct swap_info_struct *sis,
	142	struct file *swap_file,
	143	sector_t *span)
	144	{
	145	struct address_space *mapping = swap_file->f_mapping;
	146	struct inode *inode = mapping->host;
	147	unsigned blocks_per_page;
	148	unsigned long page_no;
	149	unsigned blkbits;
	150	sector_t probe_block;
	151	sector_t last_block;
	152	sector_t lowest_block = -1;
	153	sector_t highest_block = 0;
	154	int nr_extents = 0;
	155	int ret;
	156
	157	blkbits = inode->i_blkbits;
	158	blocks_per_page = PAGE_SIZE >> blkbits;
	159
	160	/*
	161	* Map all the blocks into the extent list. This code doesn't try
	162	* to be very smart.
	163	*/
	164	probe_block = 0;
	165	page_no = 0;
	166	last_block = i_size_read(inode) >> blkbits;
	167	while ((probe_block + blocks_per_page) <= last_block &&
	168	page_no < sis->max) {
	169	unsigned block_in_page;
	170	sector_t first_block;
	171
7e4411bf MP	172	cond_resched();
7e4411bf MP	173
a509bc1a MG	174	first_block = bmap(inode, probe_block);
	175	if (first_block == 0)
	176	goto bad_bmap;
	177
	178	/*
	179	* It must be PAGE_SIZE aligned on-disk
	180	*/
	181	if (first_block & (blocks_per_page - 1)) {
	182	probe_block++;
	183	goto reprobe;
	184	}
	185
	186	for (block_in_page = 1; block_in_page < blocks_per_page;
	187	block_in_page++) {
	188	sector_t block;
	189
	190	block = bmap(inode, probe_block + block_in_page);
	191	if (block == 0)
	192	goto bad_bmap;
	193	if (block != first_block + block_in_page) {
	194	/* Discontiguity */
	195	probe_block++;
	196	goto reprobe;
	197	}
	198	}
	199
	200	first_block >>= (PAGE_SHIFT - blkbits);
	201	if (page_no) { /* exclude the header page */
	202	if (first_block < lowest_block)
	203	lowest_block = first_block;
	204	if (first_block > highest_block)
	205	highest_block = first_block;
	206	}
	207
	208	/*
	209	* We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
	210	*/
	211	ret = add_swap_extent(sis, page_no, 1, first_block);
	212	if (ret < 0)
	213	goto out;
	214	nr_extents += ret;
	215	page_no++;
	216	probe_block += blocks_per_page;
	217	reprobe:
	218	continue;
	219	}
	220	ret = nr_extents;
	221	*span = 1 + highest_block - lowest_block;
	222	if (page_no == 0)
	223	page_no = 1; /* force Empty message */
	224	sis->max = page_no;
	225	sis->pages = page_no - 1;
	226	sis->highest_bit = page_no - 1;
	227	out:
	228	return ret;
	229	bad_bmap:
1170532b	230	pr_err("swapon: swapfile has holes\n");
a509bc1a MG	231	ret = -EINVAL;
	232	goto out;
	233	}
	234
1da177e4 LT	235	/*
	236	* We may have stale swap cache pages in memory: notice
	237	* them here and get rid of the unnecessary final write.
	238	*/
	239	int swap_writepage(struct page page, struct writeback_control wbc)
	240	{
2f772e6c	241	int ret = 0;
1da177e4	242
a2c43eed	243	if (try_to_free_swap(page)) {
1da177e4 LT	244	unlock_page(page);
	245	goto out;
	246	}
165c8aed	247	if (frontswap_store(page) == 0) {
38b5faf4 DM	248	set_page_writeback(page);
	249	unlock_page(page);
	250	end_page_writeback(page);
	251	goto out;
	252	}
1eec6702	253	ret = __swap_writepage(page, wbc, end_swap_bio_write);
2f772e6c SJ	254	out:
	255	return ret;
	256	}
	257
dd6bd0d9 MW	258	static sector_t swap_page_sector(struct page *page)
dd6bd0d9 MW	259	{
09cbfeaf	260	return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9);
dd6bd0d9 MW	261	}
dd6bd0d9 MW	262
1eec6702	263	int __swap_writepage(struct page page, struct writeback_control wbc,
4246a0b6	264	bio_end_io_t end_write_func)
2f772e6c SJ	265	{
2f772e6c SJ	266	struct bio *bio;
4e49ea4a	267	int ret;
2f772e6c	268	struct swap_info_struct *sis = page_swap_info(page);
62c230bc	269
cc30c5d6	270	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
62c230bc MG	271	if (sis->flags & SWP_FILE) {
	272	struct kiocb kiocb;
	273	struct file *swap_file = sis->swap_file;
	274	struct address_space *mapping = swap_file->f_mapping;
62a8067a AV	275	struct bio_vec bv = {
	276	.bv_page = page,
	277	.bv_len = PAGE_SIZE,
	278	.bv_offset = 0
	279	};
05afcb77	280	struct iov_iter from;
62c230bc	281
05afcb77	282	iov_iter_bvec(&from, ITER_BVEC \| WRITE, &bv, 1, PAGE_SIZE);
62c230bc MG	283	init_sync_kiocb(&kiocb, swap_file);
62c230bc MG	284	kiocb.ki_pos = page_file_offset(page);
62c230bc	285
0cdc444a	286	set_page_writeback(page);
62c230bc	287	unlock_page(page);
c8b8e32d	288	ret = mapping->a_ops->direct_IO(&kiocb, &from);
62c230bc MG	289	if (ret == PAGE_SIZE) {
	290	count_vm_event(PSWPOUT);
	291	ret = 0;
2d30d31e	292	} else {
0cdc444a MG	293	/*
	294	* In the case of swap-over-nfs, this can be a
	295	* temporary failure if the system has limited
	296	* memory for allocating transmit buffers.
	297	* Mark the page dirty and avoid
	298	* rotate_reclaimable_page but rate-limit the
	299	* messages but do not flag PageError like
	300	* the normal direct-to-bio case as it could
	301	* be temporary.
	302	*/
2d30d31e	303	set_page_dirty(page);
0cdc444a	304	ClearPageReclaim(page);
1170532b JP	305	pr_err_ratelimited("Write error on dio swapfile (%llu)\n",
1170532b JP	306	page_file_offset(page));
62c230bc	307	}
0cdc444a	308	end_page_writeback(page);
62c230bc MG	309	return ret;
	310	}
	311
dd6bd0d9 MW	312	ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
	313	if (!ret) {
	314	count_vm_event(PSWPOUT);
	315	return 0;
	316	}
	317
	318	ret = 0;
1eec6702	319	bio = get_swap_bio(GFP_NOIO, page, end_write_func);
1da177e4 LT	320	if (bio == NULL) {
	321	set_page_dirty(page);
	322	unlock_page(page);
	323	ret = -ENOMEM;
	324	goto out;
	325	}
7637241e	326	bio->bi_opf = REQ_OP_WRITE \| wbc_to_write_flags(wbc);
f8891e5e	327	count_vm_event(PSWPOUT);
1da177e4 LT	328	set_page_writeback(page);
1da177e4 LT	329	unlock_page(page);
4e49ea4a	330	submit_bio(bio);
1da177e4 LT	331	out:
	332	return ret;
	333	}
	334
23955622	335	int swap_readpage(struct page *page, bool do_poll)
1da177e4 LT	336	{
	337	struct bio *bio;
	338	int ret = 0;
62c230bc	339	struct swap_info_struct *sis = page_swap_info(page);
23955622 SL	340	blk_qc_t qc;
23955622 SL	341	struct block_device *bdev;
1da177e4	342
cc30c5d6	343	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
309381fe SL	344	VM_BUG_ON_PAGE(!PageLocked(page), page);
309381fe SL	345	VM_BUG_ON_PAGE(PageUptodate(page), page);
165c8aed	346	if (frontswap_load(page) == 0) {
38b5faf4 DM	347	SetPageUptodate(page);
	348	unlock_page(page);
	349	goto out;
	350	}
62c230bc MG	351
	352	if (sis->flags & SWP_FILE) {
	353	struct file *swap_file = sis->swap_file;
	354	struct address_space *mapping = swap_file->f_mapping;
	355
	356	ret = mapping->a_ops->readpage(swap_file, page);
	357	if (!ret)
	358	count_vm_event(PSWPIN);
	359	return ret;
	360	}
	361
dd6bd0d9 MW	362	ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
dd6bd0d9 MW	363	if (!ret) {
b06bad17 MK	364	if (trylock_page(page)) {
	365	swap_slot_free_notify(page);
	366	unlock_page(page);
	367	}
	368
dd6bd0d9 MW	369	count_vm_event(PSWPIN);
	370	return 0;
	371	}
	372
	373	ret = 0;
f29ad6a9	374	bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
1da177e4 LT	375	if (bio == NULL) {
	376	unlock_page(page);
	377	ret = -ENOMEM;
	378	goto out;
	379	}
23955622 SL	380	bdev = bio->bi_bdev;
23955622 SL	381	bio->bi_private = current;
95fe6c1a	382	bio_set_op_attrs(bio, REQ_OP_READ, 0);
f8891e5e	383	count_vm_event(PSWPIN);
23955622 SL	384	bio_get(bio);
	385	qc = submit_bio(bio);
	386	while (do_poll) {
	387	set_current_state(TASK_UNINTERRUPTIBLE);
	388	if (!READ_ONCE(bio->bi_private))
	389	break;
	390
	391	if (!blk_mq_poll(bdev_get_queue(bdev), qc))
	392	break;
	393	}
	394	__set_current_state(TASK_RUNNING);
	395	bio_put(bio);
	396
1da177e4 LT	397	out:
	398	return ret;
	399	}
62c230bc MG	400
	401	int swap_set_page_dirty(struct page *page)
	402	{
	403	struct swap_info_struct *sis = page_swap_info(page);
	404
	405	if (sis->flags & SWP_FILE) {
	406	struct address_space *mapping = sis->swap_file->f_mapping;
cc30c5d6 AM	407
cc30c5d6 AM	408	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
62c230bc MG	409	return mapping->a_ops->set_page_dirty(page);
	410	} else {
	411	return __set_page_dirty_no_writeback(page);
	412	}
	413	}