[PATCH v2] include/linux/swap.h: Remove unused leftovers

["Ritesh Harjani (IBM)" <ritesh.list@gmail.com>]

This removed unused leftovers, most of them are forward structure
declarations. Also removes SWAP_BATCH macro which isn't used any
where in the code.

Found these during manual code review.

Reviewed-by: Barry Song <baohua@kernel.org>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
RFC -> v2:
- separated from the rest of the series (enable thp swap on PowerPC Book3s64)
- RB from Barry
[RFC]: https://lore.kernel.org/linuxppc-dev/cover.1781000840.git.ritesh.list@gmail.com/

 include/linux/swap.h | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 8f0f68e245ba..46c25523d7b8 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -16,10 +16,6 @@
 #include <uapi/linux/mempolicy.h>
 #include <asm/page.h>

-struct notifier_block;
-
-struct bio;
-
 #define SWAP_FLAG_PREFER	0x8000	/* set if swap priority specified */
 #define SWAP_FLAG_PRIO_MASK	0x7fff
 #define SWAP_FLAG_DISCARD	0x10000 /* enable discard for swap */
@@ -29,7 +25,6 @@ struct bio;
 #define SWAP_FLAGS_VALID	(SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
 				 SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \
 				 SWAP_FLAG_DISCARD_PAGES)
-#define SWAP_BATCH 64

 static inline int current_is_kswapd(void)
 {
@@ -175,7 +170,6 @@ static inline void mm_account_reclaimed_pages(unsigned long pages)

 struct address_space;
 struct sysinfo;
-struct writeback_control;
 struct zone;

 /*
@@ -442,7 +436,6 @@ extern sector_t swapdev_block(int, pgoff_t);
 extern int __swap_count(swp_entry_t entry);
 extern bool swap_entry_swapped(struct swap_info_struct *si, swp_entry_t entry);
 extern int swp_swapcount(swp_entry_t entry);
-struct backing_dev_info;
 extern struct swap_info_struct *get_swap_device(swp_entry_t entry);
 sector_t swap_folio_sector(struct folio *folio);

--
2.39.5