mm: frontswap: cleanup code

After allowing tmem backends to build/run as modules, frontswap_enabled
always true if defined CONFIG_FRONTSWAP.  But frontswap_test() depends on
whether backend is registered, mv it into frontswap.c using fronstswap_ops
to make the decision.

frontswap_set/clear are not used outside frontswap, so don't export them.

Signed-off-by: Bob Liu <lliubbo@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andor Daam <andor.daam@googlemail.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Florian Schmaus <fschmaus@gmail.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Stefan Hengelein <ilendir@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 25 deletions

diff --git a/include/linux/frontswap.h b/include/linux/frontswap.h
index d4f29875c7cc..6c49e1eba552 100644
--- a/include/linux/frontswap.h
+++ b/include/linux/frontswap.h
@@ -22,6 +22,7 @@ extern void frontswap_writethrough(bool);
 #define FRONTSWAP_HAS_EXCLUSIVE_GETS
 extern void frontswap_tmem_exclusive_gets(bool);
 
+extern bool __frontswap_test(struct swap_info_struct *, pgoff_t);
 extern void __frontswap_init(unsigned type);
 extern int __frontswap_store(struct page *page);
 extern int __frontswap_load(struct page *page);
@@ -29,26 +30,11 @@ extern void __frontswap_invalidate_page(unsigned, pgoff_t);
 extern void __frontswap_invalidate_area(unsigned);
 
 #ifdef CONFIG_FRONTSWAP
+#define frontswap_enabled (1)
 
 static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
 {
-        bool ret = false;
-
-        if (frontswap_enabled && sis->frontswap_map)
-                ret = test_bit(offset, sis->frontswap_map);
-        return ret;
-}
-
-static inline void frontswap_set(struct swap_info_struct *sis, pgoff_t offset)
-{
-        if (frontswap_enabled && sis->frontswap_map)
-                set_bit(offset, sis->frontswap_map);
-}
-
-static inline void frontswap_clear(struct swap_info_struct *sis, pgoff_t offset)
-{
-        if (frontswap_enabled && sis->frontswap_map)
-                clear_bit(offset, sis->frontswap_map);
+        return __frontswap_test(sis, offset);
 }
 
 static inline void frontswap_map_set(struct swap_info_struct *p,
@@ -71,14 +57,6 @@ static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
         return false;
 }
 
-static inline void frontswap_set(struct swap_info_struct *sis, pgoff_t offset)
-{
-}
-
-static inline void frontswap_clear(struct swap_info_struct *sis, pgoff_t offset)
-{
-}
-
 static inline void frontswap_map_set(struct swap_info_struct *p,
                                      unsigned long *map)
 {