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: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 9f0ca32..a2602a8 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -325,7 +325,7 @@
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 *);
diff --git a/mm/page_io.c b/mm/page_io.c
index afeed89..a19af95 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -26,9 +26,7 @@
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;
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 58bec66..d5eb2e8 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -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 @@
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 @@
/*
* 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;
@@ -1281,6 +1283,16 @@
}
/*
+ * 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
*/
static void destroy_swap_extents(struct swap_info_struct *sis)