linux-ext4 - Re: [PATCH] ext4 : Remove redundant condition in ext4_free_blocks

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Date:	01 Jun 2008 09:25:19 +0300
From:	Kari Hurtta <hurtta+gmane@...lo.fmi.fi>
To:	linux-ext4@...r.kernel.org
Cc:	linux-fsdevel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject:  Re: [PATCH] ext4 : Remove redundant condition in ext4_free_blocks_sb()

"Manish Katiyar" <mkatiyar@...il.com> writes in
gmane.linux.file-systems:

> For two unsigned values the check "block+count < block"  is always
> false. Thus the below patch removes that condition.
> 
> =============================================================
> 
> Signed-off-by: Manish Katiyar <mkatiyar@...il.com>
> 
> --- a/fs/ext4/balloc.c  2008-05-18 18:07:45.000000000 +0530
> +++ b/fs/ext4/balloc.c  2008-06-01 00:05:48.000000000 +0530
> @@ -619,7 +619,6 @@
>         sbi = EXT4_SB(sb);
>         es = sbi->s_es;
>         if (block < le32_to_cpu(es->s_first_data_block) ||
> -           block + count < block ||
>             block + count > ext4_blocks_count(es)) {
>                 ext4_error (sb, "ext4_free_blocks",
>                             "Freeing blocks not in datazone - "
> 
> 
> =============================================================

Hmm. Consider situation where   block + count > max unsigned value
     mathematically

     in that case 
           block + count < block
     expression may be true

 
> -- 
> Thanks & Regards,
> ********************************************
> Manish Katiyar ( http://mkatiyar.googlepages.com )
> 3rd Floor, Fair Winds Block
> EGL Software Park
> Off Intermediate Ring Road
> Bangalore 560071, India
> ***********************************************
> --
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/ Kari Hurtta

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