[linux.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/pagemap.h>
#include <linux/swap.h>
#include <linux/bio.h>
#include <linux/swapops.h>
#include <linux/writeback.h>
#include <asm/pgtable.h>

static struct bio *get_swap_bio(unsigned int __nocast gfp_flags, pgoff_t index,
				struct page *page, bio_end_io_t end_io)
{
	struct bio *bio;

	bio = bio_alloc(gfp_flags, 1);
	if (bio) {
		struct swap_info_struct *sis;
		swp_entry_t entry = { .val = index, };

		sis = get_swap_info_struct(swp_type(entry));
		bio->bi_sector = map_swap_page(sis, swp_offset(entry)) *
					(PAGE_SIZE >> 9);
		bio->bi_bdev = sis->bdev;
		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_idx = 0;
		bio->bi_size = PAGE_SIZE;
		bio->bi_end_io = end_io;
	}
	return bio;
}

static int end_swap_bio_write(struct bio *bio, unsigned int bytes_done, int err)
{
	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
	struct page *page = bio->bi_io_vec[0].bv_page;

	if (bio->bi_size)
		return 1;

	if (!uptodate)
		SetPageError(page);
	end_page_writeback(page);
	bio_put(bio);
	return 0;
}

static int end_swap_bio_read(struct bio *bio, unsigned int bytes_done, int err)
{
	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
	struct page *page = bio->bi_io_vec[0].bv_page;

	if (bio->bi_size)
		return 1;

	if (!uptodate) {
		SetPageError(page);
		ClearPageUptodate(page);
	} else {
		SetPageUptodate(page);
	}
	unlock_page(page);
	bio_put(bio);
	return 0;
}

/*
 * 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)
{
	struct bio *bio;
	int ret = 0, rw = WRITE;

	if (remove_exclusive_swap_page(page)) {
		unlock_page(page);
		goto out;
	}
	bio = get_swap_bio(GFP_NOIO, page->private, page, end_swap_bio_write);
	if (bio == NULL) {
		set_page_dirty(page);
		unlock_page(page);
		ret = -ENOMEM;
		goto out;
	}
	if (wbc->sync_mode == WB_SYNC_ALL)
		rw |= (1 << BIO_RW_SYNC);
	inc_page_state(pswpout);
	set_page_writeback(page);
	unlock_page(page);
	submit_bio(rw, bio);
out:
	return ret;
}

int swap_readpage(struct file *file, struct page *page)
{
	struct bio *bio;
	int ret = 0;

	BUG_ON(!PageLocked(page));
	ClearPageUptodate(page);
	bio = get_swap_bio(GFP_KERNEL, page->private, page, end_swap_bio_read);
	if (bio == NULL) {
		unlock_page(page);
		ret = -ENOMEM;
		goto out;
	}
	inc_page_state(pswpin);
	submit_bio(READ, bio);
out:
	return ret;
}

#ifdef CONFIG_SOFTWARE_SUSPEND
/*
 * A scruffy utility function to read or write an arbitrary swap page
 * and wait on the I/O.  The caller must have a ref on the page.
 *
 * We use end_swap_bio_read() even for writes, because it happens to do what
 * we want.
 */
int rw_swap_page_sync(int rw, swp_entry_t entry, struct page *page)
{
	struct bio *bio;
	int ret = 0;

	lock_page(page);

	bio = get_swap_bio(GFP_KERNEL, entry.val, page, end_swap_bio_read);
	if (bio == NULL) {
		unlock_page(page);
		ret = -ENOMEM;
		goto out;
	}

	submit_bio(rw | (1 << BIO_RW_SYNC), bio);
	wait_on_page_locked(page);

	if (!PageUptodate(page) || PageError(page))
		ret = -EIO;
out:
	return ret;
}
#endif
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>
	15	#include <linux/pagemap.h>
	16	#include <linux/swap.h>
	17	#include <linux/bio.h>
	18	#include <linux/swapops.h>
	19	#include <linux/writeback.h>
	20	#include <asm/pgtable.h>
	21
	22	static struct bio *get_swap_bio(unsigned int __nocast gfp_flags, pgoff_t index,
	23	struct page *page, bio_end_io_t end_io)
	24	{
	25	struct bio *bio;
	26
	27	bio = bio_alloc(gfp_flags, 1);
	28	if (bio) {
	29	struct swap_info_struct *sis;
	30	swp_entry_t entry = { .val = index, };
	31
	32	sis = get_swap_info_struct(swp_type(entry));
	33	bio->bi_sector = map_swap_page(sis, swp_offset(entry)) *
	34	(PAGE_SIZE >> 9);
	35	bio->bi_bdev = sis->bdev;
	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;
	40	bio->bi_idx = 0;
	41	bio->bi_size = PAGE_SIZE;
	42	bio->bi_end_io = end_io;
	43	}
	44	return bio;
	45	}
	46
	47	static int end_swap_bio_write(struct bio *bio, unsigned int bytes_done, int err)
	48	{
	49	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
	50	struct page *page = bio->bi_io_vec[0].bv_page;
	51
	52	if (bio->bi_size)
	53	return 1;
	54
	55	if (!uptodate)
	56	SetPageError(page);
	57	end_page_writeback(page);
	58	bio_put(bio);
	59	return 0;
	60	}
	61
	62	static int end_swap_bio_read(struct bio *bio, unsigned int bytes_done, int err)
	63	{
	64	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
65	struct page *page = bio->bi_io_vec[0].bv_page;
66
67	if (bio->bi_size)
68	return 1;
69
70	if (!uptodate) {
71	SetPageError(page);
72	ClearPageUptodate(page);
73	} else {
74	SetPageUptodate(page);
75	}
76	unlock_page(page);
77	bio_put(bio);
78	return 0;
79	}
80
81	/*
82	* We may have stale swap cache pages in memory: notice
83	* them here and get rid of the unnecessary final write.
84	*/
85	int swap_writepage(struct page page, struct writeback_control wbc)
86	{
87	struct bio *bio;
88	int ret = 0, rw = WRITE;
89
90	if (remove_exclusive_swap_page(page)) {
91	unlock_page(page);
92	goto out;
93	}
94	bio = get_swap_bio(GFP_NOIO, page->private, page, end_swap_bio_write);
95	if (bio == NULL) {
96	set_page_dirty(page);
97	unlock_page(page);
98	ret = -ENOMEM;
99	goto out;
100	}
101	if (wbc->sync_mode == WB_SYNC_ALL)
102	rw \|= (1 << BIO_RW_SYNC);
103	inc_page_state(pswpout);
104	set_page_writeback(page);
105	unlock_page(page);
106	submit_bio(rw, bio);
107	out:
108	return ret;
109	}
110
111	int swap_readpage(struct file file, struct page page)
112	{
113	struct bio *bio;
114	int ret = 0;
115
116	BUG_ON(!PageLocked(page));
117	ClearPageUptodate(page);
118	bio = get_swap_bio(GFP_KERNEL, page->private, page, end_swap_bio_read);
119	if (bio == NULL) {
120	unlock_page(page);
121	ret = -ENOMEM;
122	goto out;
123	}
124	inc_page_state(pswpin);
125	submit_bio(READ, bio);
126	out:
127	return ret;
128	}
129
648be318	130	#ifdef CONFIG_SOFTWARE_SUSPEND
1da177e4 LT	131	/*
	132	* A scruffy utility function to read or write an arbitrary swap page
	133	* and wait on the I/O. The caller must have a ref on the page.
	134	*
	135	* We use end_swap_bio_read() even for writes, because it happens to do what
	136	* we want.
	137	*/
	138	int rw_swap_page_sync(int rw, swp_entry_t entry, struct page *page)
	139	{
	140	struct bio *bio;
	141	int ret = 0;
	142
	143	lock_page(page);
	144
	145	bio = get_swap_bio(GFP_KERNEL, entry.val, page, end_swap_bio_read);
	146	if (bio == NULL) {
	147	unlock_page(page);
	148	ret = -ENOMEM;
	149	goto out;
	150	}
	151
	152	submit_bio(rw \| (1 << BIO_RW_SYNC), bio);
	153	wait_on_page_locked(page);
	154
	155	if (!PageUptodate(page) \|\| PageError(page))
	156	ret = -EIO;
	157	out:
	158	return ret;
	159	}
	160	#endif