btrfs: remove no longer used btrfs_clone_chunk_map()

There are no more users of btrfs_clone_chunk_map(), the last one (and
only one ever) was removed in commit 1ec17ef ("btrfs: zoned: fix
use-after-free in do_zone_finish()"). So remove btrfs_clone_chunk_map().

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: fdmanana

fs/btrfs/volumes.c

@@ -5614,21 +5614,6 @@ struct btrfs_chunk_map *btrfs_alloc_chunk_map(int num_stripes, gfp_t gfp)
 	return map;
 }
 
-struct btrfs_chunk_map *btrfs_clone_chunk_map(struct btrfs_chunk_map *map, gfp_t gfp)
-{
-	const int size = btrfs_chunk_map_size(map->num_stripes);
-	struct btrfs_chunk_map *clone;
-
-	clone = kmemdup(map, size, gfp);
-	if (!clone)
-		return NULL;
-
-	refcount_set(&clone->refs, 1);
-	RB_CLEAR_NODE(&clone->rb_node);
-
-	return clone;
-}
-
 static struct btrfs_block_group *create_chunk(struct btrfs_trans_handle *trans,
 			struct alloc_chunk_ctl *ctl,
 			struct btrfs_device_info *devices_info)

fs/btrfs/volumes.h

@@ -743,7 +743,6 @@ struct btrfs_chunk_map *btrfs_alloc_chunk_map(int num_stripes, gfp_t gfp);
 int btrfs_add_chunk_map(struct btrfs_fs_info *fs_info, struct btrfs_chunk_map *map);
 #endif
 
-struct btrfs_chunk_map *btrfs_clone_chunk_map(struct btrfs_chunk_map *map, gfp_t gfp);
 struct btrfs_chunk_map *btrfs_find_chunk_map(struct btrfs_fs_info *fs_info,
 					     u64 logical, u64 length);
 struct btrfs_chunk_map *btrfs_find_chunk_map_nolock(struct btrfs_fs_info *fs_info,