btrfs: move btrfs_block_group_root() to block-group.c

The function btrfs_block_group_root() is declared in disk-io.c; however,
all its callers are in block-group.c. Move it to the latter file and
declare it static.
Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/block-group.c

@@ -1022,6 +1022,13 @@ static void clear_incompat_bg_bits(struct btrfs_fs_info *fs_info, u64 flags)
 	}
 }
 
+static struct btrfs_root *btrfs_block_group_root(struct btrfs_fs_info *fs_info)
+{
+	if (btrfs_fs_compat_ro(fs_info, BLOCK_GROUP_TREE))
+		return fs_info->block_group_root;
+	return btrfs_extent_root(fs_info, 0);
+}
+
 static int remove_block_group_item(struct btrfs_trans_handle *trans,
 				   struct btrfs_path *path,
 				   struct btrfs_block_group *block_group)

fs/btrfs/disk-io.c

@@ -846,13 +846,6 @@ struct btrfs_root *btrfs_extent_root(struct btrfs_fs_info *fs_info, u64 bytenr)
 	return btrfs_global_root(fs_info, &key);
 }
 
-struct btrfs_root *btrfs_block_group_root(struct btrfs_fs_info *fs_info)
-{
-	if (btrfs_fs_compat_ro(fs_info, BLOCK_GROUP_TREE))
-		return fs_info->block_group_root;
-	return btrfs_extent_root(fs_info, 0);
-}
-
 struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 				     u64 objectid)
 {

fs/btrfs/disk-io.h

@@ -83,7 +83,6 @@ struct btrfs_root *btrfs_global_root(struct btrfs_fs_info *fs_info,
 				     struct btrfs_key *key);
 struct btrfs_root *btrfs_csum_root(struct btrfs_fs_info *fs_info, u64 bytenr);
 struct btrfs_root *btrfs_extent_root(struct btrfs_fs_info *fs_info, u64 bytenr);
-struct btrfs_root *btrfs_block_group_root(struct btrfs_fs_info *fs_info);
 
 void btrfs_free_fs_info(struct btrfs_fs_info *fs_info);
 void btrfs_btree_balance_dirty(struct btrfs_fs_info *fs_info);