mm: simplify swapdev_block

Open code the parts of map_swap_entry that was actually used by
swapdev_block, and remove the now unused map_swap_entry function.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

mm/swapfile.c

@@ -1790,9 +1790,6 @@ int free_swap_and_cache(swp_entry_t entry)
 }
 
 #ifdef CONFIG_HIBERNATION
-
-static sector_t map_swap_entry(swp_entry_t, struct block_device**);
-
 /*
  * Find the swap type that corresponds to given device (if any).
  *
@@ -1852,12 +1849,13 @@ int find_first_swap(dev_t *device)
  */
 sector_t swapdev_block(int type, pgoff_t offset)
 {
-	struct block_device *bdev;
 	struct swap_info_struct *si = swap_type_to_swap_info(type);
+	struct swap_extent *se;
 
 	if (!si || !(si->flags & SWP_WRITEOK))
 		return 0;
-	return map_swap_entry(swp_entry(type, offset), &bdev);
+	se = offset_to_swap_extent(si, offset);
+	return se->start_block + (offset - se->start_page);
 }
 
 /*
@@ -2283,28 +2281,6 @@ static void drain_mmlist(void)
 	spin_unlock(&mmlist_lock);
 }
 
-#ifdef CONFIG_HIBERNATION
-/*
- * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
- * corresponds to page offset for the specified swap entry.
- * Note that the type of this function is sector_t, but it returns page offset
- * into the bdev, not sector offset.
- */
-static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev)
-{
-	struct swap_info_struct *sis;
-	struct swap_extent *se;
-	pgoff_t offset;
-
-	sis = swp_swap_info(entry);
-	*bdev = sis->bdev;
-
-	offset = swp_offset(entry);
-	se = offset_to_swap_extent(sis, offset);
-	return se->start_block + (offset - se->start_page);
-}
-#endif
-
 /*
  * Free all of a swapdev's extent information
  */