mm: remove page_swap_info()

It's more efficient to get the swap_info_struct by calling
swp_swap_info() directly.

Link: https://lkml.kernel.org/r/20231213215842.671461-12-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/swap.h

@@ -487,8 +487,7 @@ extern sector_t swapdev_block(int, pgoff_t);
 extern int __swap_count(swp_entry_t entry);
 extern int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry);
 extern int swp_swapcount(swp_entry_t entry);
-extern struct swap_info_struct *page_swap_info(struct page *);
-extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
+struct swap_info_struct *swp_swap_info(swp_entry_t entry);
 struct backing_dev_info;
 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
 extern void exit_swap_address_space(unsigned int type);

mm/swap.h

@@ -60,7 +60,7 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
 
 static inline unsigned int folio_swap_flags(struct folio *folio)
 {
-	return page_swap_info(&folio->page)->flags;
+	return swp_swap_info(folio->swap)->flags;
 }
 #else /* CONFIG_SWAP */
 struct swap_iocb;

mm/swapfile.c

@@ -3369,18 +3369,12 @@ struct swap_info_struct *swp_swap_info(swp_entry_t entry)
 	return swap_type_to_swap_info(swp_type(entry));
 }
 
-struct swap_info_struct *page_swap_info(struct page *page)
-{
-	swp_entry_t entry = page_swap_entry(page);
-	return swp_swap_info(entry);
-}
-
 /*
  * out-of-line methods to avoid include hell.
  */
 struct address_space *swapcache_mapping(struct folio *folio)
 {
-	return page_swap_info(&folio->page)->swap_file->f_mapping;
+	return swp_swap_info(folio->swap)->swap_file->f_mapping;
 }
 EXPORT_SYMBOL_GPL(swapcache_mapping);