Commit d4906e1a authored by Lee Schermerhorn's avatar Lee Schermerhorn Committed by Linus Torvalds
Browse files

swap: rework map_swap_page() again 



Seems that page_io.c doesn't really need to know that page_private(page)
is the swp_entry 'val'.  Rework map_swap_page() to do what its name says
and map a page to a page offset in the swap space.

The only other caller of map_swap_page() is internal to mm/swapfile.c and
it does want to map a swap entry to the 'sector'.  So rename
map_swap_page() to map_swap_entry(), make it 'static' and and implement
map_swap_page() as a wrapper around that.

Signed-off-by: default avatarLee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7509765a

include/linux/swap.h

+1 −1
Original line number Diff line number Diff line
@@ -325,7 +325,7 @@ extern void swapcache_free(swp_entry_t, struct page *page); 
extern int free_swap_and_cache(swp_entry_t);

extern int swap_type_of(dev_t, sector_t, struct block_device **);

extern unsigned int count_swap_pages(int, int);

extern sector_t map_swap_page(swp_entry_t, struct block_device **);

extern sector_t map_swap_page(struct page *, struct block_device **);

extern sector_t swapdev_block(int, pgoff_t);

extern int reuse_swap_page(struct page *);

extern int try_to_free_swap(struct page *);

mm/page_io.c

+1 −3
Original line number Diff line number Diff line
@@ -26,9 +26,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags, 


	bio = bio_alloc(gfp_flags, 1);

	if (bio) {

		swp_entry_t entry;

		entry.val = page_private(page);

		bio->bi_sector = map_swap_page(entry, &bio->bi_bdev);

		bio->bi_sector = map_swap_page(page, &bio->bi_bdev);

		bio->bi_sector <<= PAGE_SHIFT - 9;

		bio->bi_io_vec[0].bv_page = page;

		bio->bi_io_vec[0].bv_len = PAGE_SIZE;

mm/swapfile.c

+16 −4
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ 
static bool swap_count_continued(struct swap_info_struct *, pgoff_t,

				 unsigned char);

static void free_swap_count_continuations(struct swap_info_struct *);

static sector_t map_swap_entry(swp_entry_t, struct block_device**);



static DEFINE_SPINLOCK(swap_lock);

static unsigned int nr_swapfiles;
@@ -782,7 +783,7 @@ sector_t swapdev_block(int type, pgoff_t offset) 
		return 0;

	if (!(swap_info[type]->flags & SWP_WRITEOK))

		return 0;

	return map_swap_page(swp_entry(type, offset), &bdev);

	return map_swap_entry(swp_entry(type, offset), &bdev);

}



/*
@@ -1249,10 +1250,11 @@ static void drain_mmlist(void) 


/*

 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which

 * corresponds to page offset `offset'.  Note that the type of this function

 * is sector_t, but it returns page offset into the bdev, not sector offset.

 * corresponds to page offset for the specified swap entry.

 * Note that the type of this function is sector_t, but it returns page offset

 * into the bdev, not sector offset.

 */

sector_t map_swap_page(swp_entry_t entry, struct block_device **bdev)

static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev)

{

	struct swap_info_struct *sis;

	struct swap_extent *start_se;
@@ -1280,6 +1282,16 @@ sector_t map_swap_page(swp_entry_t entry, struct block_device **bdev) 
	}

}



/*

 * Returns the page offset into bdev for the specified page's swap entry.

 */

sector_t map_swap_page(struct page *page, struct block_device **bdev)

{

	swp_entry_t entry;

	entry.val = page_private(page);

	return map_swap_entry(entry, bdev);

}



/*

 * Free all of a swapdev's extent information

 */

CRA Git | Maintained and supported by SUSTech CRA and CCSE