Re: [PATCH v3] btrfs: clear free space tree creation state on rebuild failure

[Boris Burkov]

On Wed, Sep 16, 2026 at 05:16:38AM +0000, Guanghui Yang wrote:
> btrfs_rebuild_free_space_tree() sets
> BTRFS_FS_CREATING_FREE_SPACE_TREE before rebuilding the free space tree.
> Several error paths return without clearing this flag.
> 
> The transaction restart failure path can leave the flag set on a live
> filesystem, causing delayed reference processing to be skipped. Clear it
> on all free space tree rebuild failure paths. Keep
> BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED set, since a failed rebuild leaves the
> free space tree untrusted. Callers must fall back to extent-tree caching.
> 
> Fixes: 882af9f13e83 ("btrfs: handle free space tree rebuild in multiple transactions")
> Cc: stable@xxxxxxxxxxxxxxx # 6.14+
> Tested:
>   xfstests btrfs/015 btrfs/032 btrfs/104 btrfs/131 btrfs/352 (pass)
>   xfstests btrfs/quick: 261 passed, 30 failed, 90 not run on
>   Ubuntu 5.15.0-60-generic
> Assisted-by: LLM

Reviewed-by: Boris Burkov <boris@xxxxxx>

> Signed-off-by: Guanghui Yang <3497809730@xxxxxx>
> ---
>  fs/btrfs/free-space-tree.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/btrfs/free-space-tree.c b/fs/btrfs/free-space-tree.c
> index 1b3d82ae3de8..b7a4a6ade30f 100644
> --- a/fs/btrfs/free-space-tree.c
> +++ b/fs/btrfs/free-space-tree.c
> @@ -1353,7 +1353,7 @@ int btrfs_rebuild_free_space_tree(struct btrfs_fs_info *fs_info)
>  	if (unlikely(ret)) {
>  		btrfs_abort_transaction(trans, ret);
>  		btrfs_end_transaction(trans);
> -		return ret;
> +		goto out_clear;
>  	}
>  
>  	node = rb_first_cached(&fs_info->block_group_cache_tree);
> @@ -1371,14 +1371,16 @@ int btrfs_rebuild_free_space_tree(struct btrfs_fs_info *fs_info)
>  		if (unlikely(ret)) {
>  			btrfs_abort_transaction(trans, ret);
>  			btrfs_end_transaction(trans);
> -			return ret;
> +			goto out_clear;
>  		}
>  next:
>  		if (btrfs_should_end_transaction(trans)) {
>  			btrfs_end_transaction(trans);
>  			trans = btrfs_start_transaction(free_space_root, 1);
> -			if (IS_ERR(trans))
> -				return PTR_ERR(trans);
> +			if (IS_ERR(trans)) {
> +				ret = PTR_ERR(trans);
> +				goto out_clear;
> +			}
>  		}
>  		node = rb_next(node);
>  	}
> @@ -1390,6 +1392,10 @@ int btrfs_rebuild_free_space_tree(struct btrfs_fs_info *fs_info)
>  	ret = btrfs_commit_transaction(trans);
>  	clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
>  	return ret;
> +
> +out_clear:
> +	clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
> +	return ret;
>  }
>  
>  static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
> 
> base-commit: 587858367581b9c55c3690f4e63382ad622719d4
> -- 
> 2.34.1
>