Ocfs2 devel - Jul 2015 - [PATCH] ocfs2: fix shift left overflow

On Mon, 27 Jul 2015 11:39:16 +0800 Joseph Qi <joseph.qi at huawei.com>
wrote:
> cluster pos is defined as u32, when calculate corresponding sector it
> should be converted to u64 first, otherwise it may overflow.
What are the runtime effects of this change?

Please always include this info when fixing bugs so that others can
work out which kernel version(s) should be patched.

On 2015/7/29 4:51, Andrew Morton wrote:
> On Mon, 27 Jul 2015 11:39:16 +0800 Joseph Qi <joseph.qi at
huawei.com> wrote:
> 
>> cluster pos is defined as u32, when calculate corresponding sector it
>> should be converted to u64 first, otherwise it may overflow.
> 
> What are the runtime effects of this change?
> 
The issue is when using large volume, for example, 9T volume with 2T already
used, frequently create small files with O_DIRECT and the IO is not cluster
aligned, it may clear sectors in the wrong place.
> Please always include this info when fixing bugs so that others can
> work out which kernel version(s) should be patched.
> 
Sorry, I'll bear it in mind.
> 
>