frontswap: simplify frontswap_init

Just use IS_ENABLED() and remove the __frontswap_init indirection.

Also remove the unused export.

Link: https://lkml.kernel.org/r/20211224062246.1258487-7-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: Christoph Hellwig

include/linux/frontswap.h

@@ -26,7 +26,7 @@ struct frontswap_ops {
 extern void frontswap_register_ops(struct frontswap_ops *ops);
 
 extern bool __frontswap_test(struct swap_info_struct *, pgoff_t);
-extern void __frontswap_init(unsigned type, unsigned long *map);
+extern void frontswap_init(unsigned type, unsigned long *map);
 extern int __frontswap_store(struct page *page);
 extern int __frontswap_load(struct page *page);
 extern void __frontswap_invalidate_page(unsigned, pgoff_t);
@@ -107,11 +107,4 @@ static inline void frontswap_invalidate_area(unsigned type)
 		__frontswap_invalidate_area(type);
 }
 
-static inline void frontswap_init(unsigned type, unsigned long *map)
-{
-#ifdef CONFIG_FRONTSWAP
-	__frontswap_init(type, map);
-#endif
-}
-
 #endif /* _LINUX_FRONTSWAP_H */

mm/frontswap.c

@@ -156,7 +156,7 @@ EXPORT_SYMBOL(frontswap_register_ops);
 /*
  * Called when a swap device is swapon'd.
  */
-void __frontswap_init(unsigned type, unsigned long *map)
+void frontswap_init(unsigned type, unsigned long *map)
 {
 	struct swap_info_struct *sis = swap_info[type];
 	struct frontswap_ops *ops;
@@ -179,7 +179,6 @@ void __frontswap_init(unsigned type, unsigned long *map)
 	for_each_frontswap_ops(ops)
 		ops->init(type);
 }
-EXPORT_SYMBOL(__frontswap_init);
 
 bool __frontswap_test(struct swap_info_struct *sis,
 				pgoff_t offset)

mm/swapfile.c

@@ -2463,7 +2463,8 @@ static void enable_swap_info(struct swap_info_struct *p, int prio,
 				struct swap_cluster_info *cluster_info,
 				unsigned long *frontswap_map)
 {
-	frontswap_init(p->type, frontswap_map);
+	if (IS_ENABLED(CONFIG_FRONTSWAP))
+		frontswap_init(p->type, frontswap_map);
 	spin_lock(&swap_lock);
 	spin_lock(&p->lock);
 	setup_swap_info(p, prio, swap_map, cluster_info);