swapin_readahead: move and rearrange args

swapin_readahead has never sat well in mm/memory.c: move it to mm/swap_state.c
beside its kindred read_swap_cache_async.  Why were its args in a different
order?  rearrange them.  And since it was always followed by a
read_swap_cache_async of the target page, fold that in and return struct
page*.  Then CONFIG_SWAP=n no longer needs valid_swaphandles and
read_swap_cache_async stubs.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-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>

1 files changed, 7 insertions, 12 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 4f3838a..9fa1aef 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -158,9 +158,6 @@ struct swap_list_t {
 /* Swap 50% full? Release swapcache more aggressively.. */
 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 
-/* linux/mm/memory.c */
-extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);
-
 /* linux/mm/page_alloc.c */
 extern unsigned long totalram_pages;
 extern unsigned long totalreserve_pages;
@@ -230,9 +227,12 @@ extern int move_from_swap_cache(struct page *, unsigned long,
 		struct address_space *);
 extern void free_page_and_swap_cache(struct page *);
 extern void free_pages_and_swap_cache(struct page **, int);
-extern struct page * lookup_swap_cache(swp_entry_t);
-extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
-					   unsigned long addr);
+extern struct page *lookup_swap_cache(swp_entry_t);
+extern struct page *read_swap_cache_async(swp_entry_t,
+			struct vm_area_struct *vma, unsigned long addr);
+extern struct page *swapin_readahead(swp_entry_t,
+			struct vm_area_struct *vma, unsigned long addr);
+
 /* linux/mm/swapfile.c */
 extern long total_swap_pages;
 extern unsigned int nr_swapfiles;
@@ -306,7 +306,7 @@ static inline void swap_free(swp_entry_t swp)
 {
 }
 
-static inline struct page *read_swap_cache_async(swp_entry_t swp,
+static inline struct page *swapin_readahead(swp_entry_t swp,
 			struct vm_area_struct *vma, unsigned long addr)
 {
 	return NULL;
@@ -317,11 +317,6 @@ static inline struct page *lookup_swap_cache(swp_entry_t swp)
 	return NULL;
 }
 
-static inline int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
-{
-	return 0;
-}
-
 #define can_share_swap_page(p)			(page_mapcount(p) == 1)
 
 static inline int move_to_swap_cache(struct page *page, swp_entry_t entry)