mm: kill page_queue_congested()

page_queue_congested() was introduced in 2002, but it was never used
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/swapfile.c

@@ -1372,26 +1372,6 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
 	return ret;
 }
 
-#if 0	/* We don't need this yet */
-#include <linux/backing-dev.h>
-int page_queue_congested(struct page *page)
-{
-	struct backing_dev_info *bdi;
-
-	VM_BUG_ON(!PageLocked(page));	/* It pins the swap_info_struct */
-
-	if (PageSwapCache(page)) {
-		swp_entry_t entry = { .val = page_private(page) };
-		struct swap_info_struct *sis;
-
-		sis = get_swap_info_struct(swp_type(entry));
-		bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info;
-	} else
-		bdi = page->mapping->backing_dev_info;
-	return bdi_write_congested(bdi);
-}
-#endif
-
 asmlinkage long sys_swapoff(const char __user * specialfile)
 {
 	struct swap_info_struct * p = NULL;