swap_info: private to swapfile.c
The swap_info_struct is mostly private to mm/swapfile.c, with only
one other in-tree user: get_swap_bio(). Adjust its interface to
map_swap_page(), so that we can then remove get_swap_info_struct().
But there is a popular user out-of-tree, TuxOnIce: so leave the
declaration of swap_info_struct in linux/swap.h.
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Nigel Cunningham <ncunningham@crca.org.au>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
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 abce8a0..82aa7e1 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -318,9 +318,8 @@
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(struct swap_info_struct *, pgoff_t);
+extern sector_t map_swap_page(swp_entry_t, struct block_device **);
extern sector_t swapdev_block(int, pgoff_t);
-extern struct swap_info_struct *get_swap_info_struct(unsigned);
extern int reuse_swap_page(struct page *);
extern int try_to_free_swap(struct page *);
struct backing_dev_info;
diff --git a/mm/page_io.c b/mm/page_io.c
index c6f3e50..afeed89 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -19,20 +19,17 @@
#include <linux/writeback.h>
#include <asm/pgtable.h>
-static struct bio *get_swap_bio(gfp_t gfp_flags, pgoff_t index,
+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) {
- 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;
+ swp_entry_t entry;
+ entry.val = page_private(page);
+ bio->bi_sector = map_swap_page(entry, &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;
bio->bi_io_vec[0].bv_offset = 0;
@@ -102,8 +99,7 @@
unlock_page(page);
goto out;
}
- bio = get_swap_bio(GFP_NOIO, page_private(page), page,
- end_swap_bio_write);
+ bio = get_swap_bio(GFP_NOIO, page, end_swap_bio_write);
if (bio == NULL) {
set_page_dirty(page);
unlock_page(page);
@@ -127,8 +123,7 @@
VM_BUG_ON(!PageLocked(page));
VM_BUG_ON(PageUptodate(page));
- bio = get_swap_bio(GFP_KERNEL, page_private(page), page,
- end_swap_bio_read);
+ bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
if (bio == NULL) {
unlock_page(page);
ret = -ENOMEM;
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 9c590ee..f83f1c6 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1283,12 +1283,22 @@
/*
* Use this swapdev's extent info to locate the (PAGE_SIZE) block which
- * corresponds to page offset `offset'.
+ * 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.
*/
-sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset)
+sector_t map_swap_page(swp_entry_t entry, struct block_device **bdev)
{
- struct swap_extent *se = sis->curr_swap_extent;
- struct swap_extent *start_se = se;
+ struct swap_info_struct *sis;
+ struct swap_extent *start_se;
+ struct swap_extent *se;
+ pgoff_t offset;
+
+ sis = swap_info + swp_type(entry);
+ *bdev = sis->bdev;
+
+ offset = swp_offset(entry);
+ start_se = sis->curr_swap_extent;
+ se = start_se;
for ( ; ; ) {
struct list_head *lh;
@@ -1314,12 +1324,14 @@
sector_t swapdev_block(int swap_type, pgoff_t offset)
{
struct swap_info_struct *sis;
+ struct block_device *bdev;
if (swap_type >= nr_swapfiles)
return 0;
sis = swap_info + swap_type;
- return (sis->flags & SWP_WRITEOK) ? map_swap_page(sis, offset) : 0;
+ return (sis->flags & SWP_WRITEOK) ?
+ map_swap_page(swp_entry(swap_type, offset), &bdev) : 0;
}
#endif /* CONFIG_HIBERNATION */
@@ -2159,13 +2171,6 @@
return __swap_duplicate(entry, SWAP_CACHE);
}
-
-struct swap_info_struct *
-get_swap_info_struct(unsigned type)
-{
- return &swap_info[type];
-}
-
/*
* swap_lock prevents swap_map being freed. Don't grab an extra
* reference on the swaphandle, it doesn't matter if it becomes unused.