Re: [PATCH] fs: btrfs: prevent unintentional int overflow

[Cengiz Can <cengiz@kernel.wtf>]

On January 6, 2020 18:53:40 David Sterba <dsterba@suse.cz> wrote:

> The overflow can't happen in practice. Taking generous maximum value for
> an item and sectorsize (64K) and doing the math will reach nowhere the
> overflow limit for 32bit type:
>
> 64K / 4 * 64K = 1G

I didn't know that. Thanks for sharing.

> I'm not sure if this is worth adding the cast, or mark the coverity
> issue as not important.

If the cast is adding any overhead (which I don't think it does) I would 
kindly request adding it for the sake of completeness.

For example: if some newbie like me tries adding something, they would be 
warned that we should consider possible overflows and/or at least be 
careful with expressions that contain different sized integers.

If this sounds unnecessary, I will help with marking the Coverity issue as 
unimportant.

Thank you!