Re: [PATCH v2] btrfs: replace BUG_ON() with error return in cache_save_setup()

[Qu Wenruo]

在 2026/3/28 17:10, Teng Liu 写道:
> In cache_save_setup(), if create_free_space_inode() succeeds but the
> subsequent lookup_free_space_inode() still fails on retry, the
> BUG_ON(retries) will crash the kernel. This can happen due to I/O
> errors or transient failures, not just programming bugs.
>
> Replace the BUG_ON with proper error handling that returns the original
> error code through the existing cleanup path. The callers already handle
> this gracefully: disk_cache_state defaults to BTRFS_DC_ERROR, so the
> space cache simply won't be written for that block group.
>
> Signed-off-by: Teng Liu <27rabbitlt@xxxxxxxxx>

Reviewed-by: Qu Wenruo <wqu@xxxxxxxx>

And pushed to for-next.

> ---
> Changes in v2:
>    - Use btrfs_err() instead of btrfs_debug() (Qu Wenruo)
>    - Use PTR_ERR(inode) instead of hardcoded -EIO (Qu Wenruo)
>    - Include error code in the log message (Qu Wenruo)
>
>   fs/btrfs/block-group.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
> index ebf507909..89bfc9db0 100644
> --- a/fs/btrfs/block-group.c
> +++ b/fs/btrfs/block-group.c
> @@ -3343,7 +3343,13 @@ static int cache_save_setup(struct btrfs_block_group *block_group,
>   	}
>   
>   	if (IS_ERR(inode)) {
> -		BUG_ON(retries);
> +		if (retries) {
> +			ret = PTR_ERR(inode);
> +			btrfs_err(fs_info,
> +				  "failed to lookup free space inode after creation for block group %llu: %d",
> +				  block_group->start, ret);
> +			goto out_free;
> +		}
>   		retries++;
>   
>   		if (block_group->ro)