Re: [PATCH v2] fs/btrfs: Fix uninitialized variable

[David Sterba]

On Sat, Apr 17, 2021 at 04:36:16PM +0100, Khaled ROMDHANI wrote:
> As reported by the Coverity static analysis.
> The variable zone is not initialized which
> may causes a failed assertion.
> 
> Addresses-Coverity: ("Uninitialized variables")
> Signed-off-by: Khaled ROMDHANI <khaledromdhani216@xxxxxxxxx>
> ---
> v2: add a default case as proposed by David Sterba
> ---
>  fs/btrfs/zoned.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
> index eeb3ebe11d7a..82527308d165 100644
> --- a/fs/btrfs/zoned.c
> +++ b/fs/btrfs/zoned.c
> @@ -143,6 +143,9 @@ static inline u32 sb_zone_number(int shift, int mirror)
>  	case 0: zone = 0; break;
>  	case 1: zone = 1ULL << (BTRFS_SB_LOG_FIRST_SHIFT - shift); break;
>  	case 2: zone = 1ULL << (BTRFS_SB_LOG_SECOND_SHIFT - shift); break;
> +	default:
> +		zone = 0;

Well yeah but this is not a valid case at all, we'd rather catch that as
an assertion failure than letting is silently continue.