btrfs: move btrfs_get_block_group helper out of disk-io.h

This inline helper calls btrfs_fs_compat_ro(), which is defined in
another header.  To avoid weird header dependency problems move this
helper into disk-io.c with the rest of the global root helpers.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

@@ -1167,6 +1167,13 @@ 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

@@ -75,6 +75,7 @@ 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);
 int btrfs_cleanup_fs_roots(struct btrfs_fs_info *fs_info);
@@ -106,13 +107,6 @@ static inline struct btrfs_root *btrfs_grab_root(struct btrfs_root *root)
 	return NULL;
 }
 
-static inline 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);
-}
-
 void btrfs_put_root(struct btrfs_root *root);
 void btrfs_mark_buffer_dirty(struct extent_buffer *buf);
 int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid,