Re: [PATCH v2 6/6] btrfs: qgroup: fix off-by-one max level check in qgroup_trace_new_subtree_blocks()

[Qu Wenruo <wqu@suse.com>]

在 2026/10/4 03:30, fdmanana@kernel.org 写道:
> From: Filipe Manana <fdmanana@suse.com>
> 
> We have maximum of 8 (BTRFS_MAX_LEVEL) levels in a btree, going from 0 to
> 7, so the upper bound checks should be:
> 
>    >= BTRFS_MAX_LEVEL
> 
> and not:
> 
>    >= BTRFS_MAX_LEVEL - 1
> 
> In practice this will hardly ever be a problem since having a btree with
> 8 levels would imply a massively huge fs.
> 
> Signed-off-by: Filipe Manana <fdmanana@suse.com>

Reviewed-by: Qu Wenruo <wqu@suse.com>

Thanks,
Qu

> ---
>   fs/btrfs/qgroup.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index c9fc3b6a5132..54d82d6fd4bb 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -2491,8 +2491,8 @@ static int qgroup_trace_new_subtree_blocks(struct btrfs_trans_handle* trans,
>   	int i;
>   
>   	/* Level sanity check */
> -	if (unlikely(cur_level < 0 || cur_level >= BTRFS_MAX_LEVEL - 1 ||
> -		     root_level < 0 || root_level >= BTRFS_MAX_LEVEL - 1 ||
> +	if (unlikely(cur_level < 0 || cur_level >= BTRFS_MAX_LEVEL ||
> +		     root_level < 0 || root_level >= BTRFS_MAX_LEVEL ||
>   		     root_level < cur_level)) {
>   		btrfs_err_rl(fs_info,
>   			"%s: bad levels, cur_level=%d root_level=%d",