[mirror_ubuntu-jammy-kernel.git] / mm / page_io.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  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/psi.h>
#include <linux/uio.h>
#include <linux/sched/task.h>

void end_swap_bio_write(struct bio *bio)
{
	struct page *page = bio_first_page_all(bio);

	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_ratelimited("Write-error on swap-device (%u:%u:%llu)\n",
				     MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
				     (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_first_page_all(bio);
	struct task_struct *waiter = bio->bi_private;

	if (bio->bi_status) {
		SetPageError(page);
		ClearPageUptodate(page);
		pr_alert_ratelimited("Read-error on swap-device (%u:%u:%llu)\n",
				     MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
				     (unsigned long long)bio->bi_iter.bi_sector);
		goto out;
	}

	SetPageUptodate(page);
out:
	unlock_page(page);
	WRITE_ONCE(bio->bi_private, NULL);
	bio_put(bio);
	if (waiter) {
		blk_wake_io_task(waiter);
		put_task_struct(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 tree.  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 = probe_block;
		ret = bmap(inode, &first_block);
		if (ret || !first_block)
			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 = probe_block + block_in_page;
			ret = bmap(inode, &block);
			if (ret || !block)
				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;
	}
	/*
	 * Arch code may have to preserve more data than just the page
	 * contents, e.g. memory tags.
	 */
	ret = arch_prepare_to_swap(page);
	if (ret) {
		set_page_dirty(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 inline void count_swpout_vm_event(struct page *page)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
	if (unlikely(PageTransHuge(page)))
		count_vm_event(THP_SWPOUT);
#endif
	count_vm_events(PSWPOUT, thp_nr_pages(page));
}

#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
static void bio_associate_blkg_from_page(struct bio *bio, struct page *page)
{
	struct cgroup_subsys_state *css;
	struct mem_cgroup *memcg;

	memcg = page_memcg(page);
	if (!memcg)
		return;

	rcu_read_lock();
	css = cgroup_e_css(memcg->css.cgroup, &io_cgrp_subsys);
	bio_associate_blkg_from_css(bio, css);
	rcu_read_unlock();
}
#else
#define bio_associate_blkg_from_page(bio, page)		do { } while (0)
#endif /* CONFIG_MEMCG && CONFIG_BLK_CGROUP */

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 (data_race(sis->flags & SWP_FS_OPS)) {
		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, 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_swpout_vm_event(page);
		return 0;
	}

	bio = bio_alloc(GFP_NOIO, 1);
	bio_set_dev(bio, sis->bdev);
	bio->bi_iter.bi_sector = swap_page_sector(page);
	bio->bi_opf = REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc);
	bio->bi_end_io = end_write_func;
	bio_add_page(bio, page, thp_size(page), 0);

	bio_associate_blkg_from_page(bio, page);
	count_swpout_vm_event(page);
	set_page_writeback(page);
	unlock_page(page);
	submit_bio(bio);

	return 0;
}

int swap_readpage(struct page *page, bool synchronous)
{
	struct bio *bio;
	int ret = 0;
	struct swap_info_struct *sis = page_swap_info(page);
	blk_qc_t qc;
	struct gendisk *disk;
	unsigned long pflags;

	VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
	VM_BUG_ON_PAGE(!PageLocked(page), page);
	VM_BUG_ON_PAGE(PageUptodate(page), page);

	/*
	 * Count submission time as memory stall. When the device is congested,
	 * or the submitting cgroup IO-throttled, submission can be a
	 * significant part of overall IO time.
	 */
	psi_memstall_enter(&pflags);

	if (frontswap_load(page) == 0) {
		SetPageUptodate(page);
		unlock_page(page);
		goto out;
	}

	if (data_race(sis->flags & SWP_FS_OPS)) {
		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);
		goto out;
	}

	if (sis->flags & SWP_SYNCHRONOUS_IO) {
		ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
		if (!ret) {
			count_vm_event(PSWPIN);
			goto out;
		}
	}

	ret = 0;
	bio = bio_alloc(GFP_KERNEL, 1);
	bio_set_dev(bio, sis->bdev);
	bio->bi_opf = REQ_OP_READ;
	bio->bi_iter.bi_sector = swap_page_sector(page);
	bio->bi_end_io = end_swap_bio_read;
	bio_add_page(bio, page, thp_size(page), 0);

	disk = bio->bi_bdev->bd_disk;
	/*
	 * Keep this task valid during swap readpage because the oom killer may
	 * attempt to access it in the page fault retry time check.
	 */
	if (synchronous) {
		bio->bi_opf |= REQ_HIPRI;
		get_task_struct(current);
		bio->bi_private = current;
	}
	count_vm_event(PSWPIN);
	bio_get(bio);
	qc = submit_bio(bio);
	while (synchronous) {
		set_current_state(TASK_UNINTERRUPTIBLE);
		if (!READ_ONCE(bio->bi_private))
			break;

		if (!blk_poll(disk->queue, qc, true))
			blk_io_schedule();
	}
	__set_current_state(TASK_RUNNING);
	bio_put(bio);

out:
	psi_memstall_leave(&pflags);
	return ret;
}

int swap_set_page_dirty(struct page *page)
{
	struct swap_info_struct *sis = page_swap_info(page);

	if (data_race(sis->flags & SWP_FS_OPS)) {
		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
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1da177e4 LT	2	/*
	3	* linux/mm/page_io.c
	4	*
	5	* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
	6	*
	7	* Swap reorganised 29.12.95,
	8	* Asynchronous swapping added 30.12.95. Stephen Tweedie
	9	* Removed race in async swapping. 14.4.1996. Bruno Haible
	10	* Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie
	11	* Always use brw_page, life becomes simpler. 12 May 1998 Eric Biederman
	12	*/
	13
	14	#include <linux/mm.h>
	15	#include <linux/kernel_stat.h>
5a0e3ad6	16	#include <linux/gfp.h>
1da177e4 LT	17	#include <linux/pagemap.h>
	18	#include <linux/swap.h>
	19	#include <linux/bio.h>
	20	#include <linux/swapops.h>
62c230bc	21	#include <linux/buffer_head.h>
1da177e4	22	#include <linux/writeback.h>
38b5faf4	23	#include <linux/frontswap.h>
b430e9d1	24	#include <linux/blkdev.h>
93779069	25	#include <linux/psi.h>
e2e40f2c	26	#include <linux/uio.h>
b0ba2d0f	27	#include <linux/sched/task.h>
1da177e4	28
4246a0b6	29	void end_swap_bio_write(struct bio *bio)
1da177e4	30	{
263663cd	31	struct page *page = bio_first_page_all(bio);
1da177e4	32
4e4cbee9	33	if (bio->bi_status) {
1da177e4	34	SetPageError(page);
6ddab3b9 PZ	35	/*
	36	* We failed to write the page out to swap-space.
	37	* Re-dirty the page in order to avoid it being reclaimed.
	38	* Also print a dire warning that things will go BAD (tm)
	39	* very quickly.
	40	*
	41	* Also clear PG_reclaim to avoid rotate_reclaimable_page()
	42	*/
	43	set_page_dirty(page);
25eaab43 GD	44	pr_alert_ratelimited("Write-error on swap-device (%u:%u:%llu)\n",
	45	MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
	46	(unsigned long long)bio->bi_iter.bi_sector);
6ddab3b9 PZ	47	ClearPageReclaim(page);
6ddab3b9 PZ	48	}
1da177e4 LT	49	end_page_writeback(page);
1da177e4 LT	50	bio_put(bio);
1da177e4 LT	51	}
1da177e4 LT	52
4246a0b6	53	static void end_swap_bio_read(struct bio *bio)
1da177e4	54	{
263663cd	55	struct page *page = bio_first_page_all(bio);
23955622	56	struct task_struct *waiter = bio->bi_private;
1da177e4	57
4e4cbee9	58	if (bio->bi_status) {
1da177e4 LT	59	SetPageError(page);
1da177e4 LT	60	ClearPageUptodate(page);
25eaab43 GD	61	pr_alert_ratelimited("Read-error on swap-device (%u:%u:%llu)\n",
	62	MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
	63	(unsigned long long)bio->bi_iter.bi_sector);
b430e9d1	64	goto out;
1da177e4	65	}
b430e9d1 MK	66
b430e9d1 MK	67	SetPageUptodate(page);
b430e9d1	68	out:
1da177e4	69	unlock_page(page);
23955622	70	WRITE_ONCE(bio->bi_private, NULL);
1da177e4	71	bio_put(bio);
87518530 ON	72	if (waiter) {
	73	blk_wake_io_task(waiter);
	74	put_task_struct(waiter);
	75	}
1da177e4 LT	76	}
1da177e4 LT	77
a509bc1a MG	78	int generic_swapfile_activate(struct swap_info_struct *sis,
	79	struct file *swap_file,
	80	sector_t *span)
	81	{
	82	struct address_space *mapping = swap_file->f_mapping;
	83	struct inode *inode = mapping->host;
	84	unsigned blocks_per_page;
	85	unsigned long page_no;
	86	unsigned blkbits;
	87	sector_t probe_block;
	88	sector_t last_block;
	89	sector_t lowest_block = -1;
	90	sector_t highest_block = 0;
	91	int nr_extents = 0;
	92	int ret;
	93
	94	blkbits = inode->i_blkbits;
	95	blocks_per_page = PAGE_SIZE >> blkbits;
	96
	97	/*
4efaceb1	98	* Map all the blocks into the extent tree. This code doesn't try
a509bc1a MG	99	* to be very smart.
	100	*/
	101	probe_block = 0;
	102	page_no = 0;
	103	last_block = i_size_read(inode) >> blkbits;
	104	while ((probe_block + blocks_per_page) <= last_block &&
	105	page_no < sis->max) {
	106	unsigned block_in_page;
	107	sector_t first_block;
	108
7e4411bf MP	109	cond_resched();
7e4411bf MP	110
30460e1e CM	111	first_block = probe_block;
	112	ret = bmap(inode, &first_block);
	113	if (ret \|\| !first_block)
a509bc1a MG	114	goto bad_bmap;
	115
	116	/*
	117	* It must be PAGE_SIZE aligned on-disk
	118	*/
	119	if (first_block & (blocks_per_page - 1)) {
	120	probe_block++;
	121	goto reprobe;
	122	}
	123
	124	for (block_in_page = 1; block_in_page < blocks_per_page;
	125	block_in_page++) {
	126	sector_t block;
	127
30460e1e CM	128	block = probe_block + block_in_page;
	129	ret = bmap(inode, &block);
	130	if (ret \|\| !block)
a509bc1a	131	goto bad_bmap;
30460e1e	132
a509bc1a MG	133	if (block != first_block + block_in_page) {
	134	/* Discontiguity */
	135	probe_block++;
	136	goto reprobe;
	137	}
	138	}
	139
	140	first_block >>= (PAGE_SHIFT - blkbits);
	141	if (page_no) { /* exclude the header page */
	142	if (first_block < lowest_block)
	143	lowest_block = first_block;
	144	if (first_block > highest_block)
	145	highest_block = first_block;
	146	}
	147
	148	/*
	149	* We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
	150	*/
	151	ret = add_swap_extent(sis, page_no, 1, first_block);
	152	if (ret < 0)
	153	goto out;
	154	nr_extents += ret;
	155	page_no++;
	156	probe_block += blocks_per_page;
	157	reprobe:
	158	continue;
	159	}
	160	ret = nr_extents;
	161	*span = 1 + highest_block - lowest_block;
	162	if (page_no == 0)
	163	page_no = 1; /* force Empty message */
	164	sis->max = page_no;
	165	sis->pages = page_no - 1;
	166	sis->highest_bit = page_no - 1;
	167	out:
	168	return ret;
	169	bad_bmap:
1170532b	170	pr_err("swapon: swapfile has holes\n");
a509bc1a MG	171	ret = -EINVAL;
	172	goto out;
	173	}
	174
1da177e4 LT	175	/*
	176	* We may have stale swap cache pages in memory: notice
	177	* them here and get rid of the unnecessary final write.
	178	*/
	179	int swap_writepage(struct page page, struct writeback_control wbc)
	180	{
2f772e6c	181	int ret = 0;
1da177e4	182
a2c43eed	183	if (try_to_free_swap(page)) {
1da177e4 LT	184	unlock_page(page);
	185	goto out;
	186	}
8a84802e SP	187	/*
	188	* Arch code may have to preserve more data than just the page
	189	* contents, e.g. memory tags.
	190	*/
	191	ret = arch_prepare_to_swap(page);
	192	if (ret) {
	193	set_page_dirty(page);
	194	unlock_page(page);
	195	goto out;
	196	}
165c8aed	197	if (frontswap_store(page) == 0) {
38b5faf4 DM	198	set_page_writeback(page);
	199	unlock_page(page);
	200	end_page_writeback(page);
	201	goto out;
	202	}
1eec6702	203	ret = __swap_writepage(page, wbc, end_swap_bio_write);
2f772e6c SJ	204	out:
	205	return ret;
	206	}
	207
225311a4 HY	208	static inline void count_swpout_vm_event(struct page *page)
	209	{
	210	#ifdef CONFIG_TRANSPARENT_HUGEPAGE
	211	if (unlikely(PageTransHuge(page)))
	212	count_vm_event(THP_SWPOUT);
	213	#endif
6c357848	214	count_vm_events(PSWPOUT, thp_nr_pages(page));
225311a4 HY	215	}
225311a4 HY	216
a18b9b15 CH	217	#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
	218	static void bio_associate_blkg_from_page(struct bio bio, struct page page)
	219	{
	220	struct cgroup_subsys_state *css;
bcfe06bf	221	struct mem_cgroup *memcg;
a18b9b15	222
bcfe06bf RG	223	memcg = page_memcg(page);
bcfe06bf RG	224	if (!memcg)
a18b9b15 CH	225	return;
	226
	227	rcu_read_lock();
bcfe06bf	228	css = cgroup_e_css(memcg->css.cgroup, &io_cgrp_subsys);
a18b9b15 CH	229	bio_associate_blkg_from_css(bio, css);
	230	rcu_read_unlock();
	231	}
	232	#else
	233	#define bio_associate_blkg_from_page(bio, page) do { } while (0)
	234	#endif /* CONFIG_MEMCG && CONFIG_BLK_CGROUP */
	235
1eec6702	236	int __swap_writepage(struct page page, struct writeback_control wbc,
4246a0b6	237	bio_end_io_t end_write_func)
2f772e6c SJ	238	{
2f772e6c SJ	239	struct bio *bio;
4e49ea4a	240	int ret;
2f772e6c	241	struct swap_info_struct *sis = page_swap_info(page);
62c230bc	242
cc30c5d6	243	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
32646315	244	if (data_race(sis->flags & SWP_FS_OPS)) {
62c230bc MG	245	struct kiocb kiocb;
	246	struct file *swap_file = sis->swap_file;
	247	struct address_space *mapping = swap_file->f_mapping;
62a8067a AV	248	struct bio_vec bv = {
	249	.bv_page = page,
	250	.bv_len = PAGE_SIZE,
	251	.bv_offset = 0
	252	};
05afcb77	253	struct iov_iter from;
62c230bc	254
aa563d7b	255	iov_iter_bvec(&from, WRITE, &bv, 1, PAGE_SIZE);
62c230bc MG	256	init_sync_kiocb(&kiocb, swap_file);
62c230bc MG	257	kiocb.ki_pos = page_file_offset(page);
62c230bc	258
0cdc444a	259	set_page_writeback(page);
62c230bc	260	unlock_page(page);
c8b8e32d	261	ret = mapping->a_ops->direct_IO(&kiocb, &from);
62c230bc MG	262	if (ret == PAGE_SIZE) {
	263	count_vm_event(PSWPOUT);
	264	ret = 0;
2d30d31e	265	} else {
0cdc444a MG	266	/*
	267	* In the case of swap-over-nfs, this can be a
	268	* temporary failure if the system has limited
	269	* memory for allocating transmit buffers.
	270	* Mark the page dirty and avoid
	271	* rotate_reclaimable_page but rate-limit the
	272	* messages but do not flag PageError like
	273	* the normal direct-to-bio case as it could
	274	* be temporary.
	275	*/
2d30d31e	276	set_page_dirty(page);
0cdc444a	277	ClearPageReclaim(page);
1170532b JP	278	pr_err_ratelimited("Write error on dio swapfile (%llu)\n",
1170532b JP	279	page_file_offset(page));
62c230bc	280	}
0cdc444a	281	end_page_writeback(page);
62c230bc MG	282	return ret;
	283	}
	284
dd6bd0d9 MW	285	ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
dd6bd0d9 MW	286	if (!ret) {
225311a4	287	count_swpout_vm_event(page);
dd6bd0d9 MW	288	return 0;
	289	}
	290
48d15436 CH	291	bio = bio_alloc(GFP_NOIO, 1);
	292	bio_set_dev(bio, sis->bdev);
	293	bio->bi_iter.bi_sector = swap_page_sector(page);
0d1e0c7c	294	bio->bi_opf = REQ_OP_WRITE \| REQ_SWAP \| wbc_to_write_flags(wbc);
48d15436 CH	295	bio->bi_end_io = end_write_func;
	296	bio_add_page(bio, page, thp_size(page), 0);
	297
6a7f6d86	298	bio_associate_blkg_from_page(bio, page);
225311a4	299	count_swpout_vm_event(page);
1da177e4 LT	300	set_page_writeback(page);
1da177e4 LT	301	unlock_page(page);
4e49ea4a	302	submit_bio(bio);
548d9782 ML	303
548d9782 ML	304	return 0;
1da177e4 LT	305	}
1da177e4 LT	306
0bcac06f	307	int swap_readpage(struct page *page, bool synchronous)
1da177e4 LT	308	{
	309	struct bio *bio;
	310	int ret = 0;
62c230bc	311	struct swap_info_struct *sis = page_swap_info(page);
23955622	312	blk_qc_t qc;
74d46992	313	struct gendisk *disk;
93779069	314	unsigned long pflags;
1da177e4	315
0bcac06f	316	VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
309381fe SL	317	VM_BUG_ON_PAGE(!PageLocked(page), page);
309381fe SL	318	VM_BUG_ON_PAGE(PageUptodate(page), page);
93779069 MK	319
	320	/*
	321	* Count submission time as memory stall. When the device is congested,
	322	* or the submitting cgroup IO-throttled, submission can be a
	323	* significant part of overall IO time.
	324	*/
	325	psi_memstall_enter(&pflags);
	326
165c8aed	327	if (frontswap_load(page) == 0) {
38b5faf4 DM	328	SetPageUptodate(page);
	329	unlock_page(page);
	330	goto out;
	331	}
62c230bc	332
32646315	333	if (data_race(sis->flags & SWP_FS_OPS)) {
62c230bc MG	334	struct file *swap_file = sis->swap_file;
	335	struct address_space *mapping = swap_file->f_mapping;
	336
	337	ret = mapping->a_ops->readpage(swap_file, page);
	338	if (!ret)
	339	count_vm_event(PSWPIN);
93779069	340	goto out;
62c230bc MG	341	}
62c230bc MG	342
5115db10 CH	343	if (sis->flags & SWP_SYNCHRONOUS_IO) {
	344	ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
	345	if (!ret) {
5115db10 CH	346	count_vm_event(PSWPIN);
	347	goto out;
	348	}
dd6bd0d9 MW	349	}
	350
	351	ret = 0;
48d15436 CH	352	bio = bio_alloc(GFP_KERNEL, 1);
	353	bio_set_dev(bio, sis->bdev);
	354	bio->bi_opf = REQ_OP_READ;
	355	bio->bi_iter.bi_sector = swap_page_sector(page);
	356	bio->bi_end_io = end_swap_bio_read;
	357	bio_add_page(bio, page, thp_size(page), 0);
	358
309dca30	359	disk = bio->bi_bdev->bd_disk;
b0ba2d0f TH	360	/*
	361	* Keep this task valid during swap readpage because the oom killer may
	362	* attempt to access it in the page fault retry time check.
	363	*/
87518530	364	if (synchronous) {
b685a735	365	bio->bi_opf \|= REQ_HIPRI;
87518530 ON	366	get_task_struct(current);
	367	bio->bi_private = current;
	368	}
f8891e5e	369	count_vm_event(PSWPIN);
23955622 SL	370	bio_get(bio);
23955622 SL	371	qc = submit_bio(bio);
0bcac06f	372	while (synchronous) {
1ac5cd49	373	set_current_state(TASK_UNINTERRUPTIBLE);
23955622 SL	374	if (!READ_ONCE(bio->bi_private))
	375	break;
	376
0a1b8b87	377	if (!blk_poll(disk->queue, qc, true))
0f190a7a	378	blk_io_schedule();
23955622 SL	379	}
	380	__set_current_state(TASK_RUNNING);
	381	bio_put(bio);
	382
1da177e4	383	out:
93779069	384	psi_memstall_leave(&pflags);
1da177e4 LT	385	return ret;
1da177e4 LT	386	}
62c230bc MG	387
	388	int swap_set_page_dirty(struct page *page)
	389	{
	390	struct swap_info_struct *sis = page_swap_info(page);
	391
32646315	392	if (data_race(sis->flags & SWP_FS_OPS)) {
62c230bc	393	struct address_space *mapping = sis->swap_file->f_mapping;
cc30c5d6 AM	394
cc30c5d6 AM	395	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
62c230bc MG	396	return mapping->a_ops->set_page_dirty(page);
	397	} else {
	398	return __set_page_dirty_no_writeback(page);
	399	}
	400	}