From:   Andreas Dilger <adilger@dilger.ca>
Message-Id: <4423B081-F635-45FB-BFE3-0A75D8F5B0E0@dilger.ca>
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Subject: Re: [PATCH] ext4: drop an always true check
Date:   Wed, 17 Nov 2021 13:26:13 -0700
In-Reply-To: <20211115172020.57853-1-kilobyte@angband.pl>
Cc:     Theodore Ts'o <tytso@mit.edu>,
        linux-ext4 <linux-ext4@vger.kernel.org>
To:     Adam Borowski <kilobyte@angband.pl>
References: <20211115172020.57853-1-kilobyte@angband.pl>
Precedence: bulk


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On Nov 15, 2021, at 10:20 AM, Adam Borowski <kilobyte@angband.pl> wrote:
> 
> EXT_FIRST_INDEX(ptr) is ptr+12, which can't possibly be null; gcc-12
> warns about this.
> 
> Signed-off-by: Adam Borowski <kilobyte@angband.pl>

I was wondering if this was intending to check if path[depth].p_hdr was NULL,
but it is clear from the rest of the code that this could not be true, since
it is already being accessed earlier in the code, so this looks fine.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>

> ---
> fs/ext4/extents.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 0ecf819bf189..5aa279742da9 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -1496,8 +1496,7 @@ static int ext4_ext_search_left(struct inode *inode,
> 				EXT4_ERROR_INODE(inode,
> 				  "ix (%d) != EXT_FIRST_INDEX (%d) (depth %d)!",
> 				  ix != NULL ? le32_to_cpu(ix->ei_block) : 0,
> -				  EXT_FIRST_INDEX(path[depth].p_hdr) != NULL ?
> -		le32_to_cpu(EXT_FIRST_INDEX(path[depth].p_hdr)->ei_block) : 0,
> +				  le32_to_cpu(EXT_FIRST_INDEX(path[depth].p_hdr)->ei_block),
> 				  depth);
> 				return -EFSCORRUPTED;
> 			}
> --
> 2.33.1
> 


Cheers, Andreas


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