[Ocfs2-devel] 答复: Bug report and patch request reviews, thanks

[Guozhonghua]

The variables ip_clusters type is unsigned int, and c_to_s_bits type is int.
So after bits moved, the result will int, that may be overflowed.

It is better to return the block count directly.
return (blkcnt_t)OCFS2_I(inode)->ip_clusters << c_to_s_bits;

-----邮件原件-----
发件人: Joseph Qi [mailto:joseph.qi at huawei.com]
发送时间: 2014年9月1日 15:37
收件人: guozhonghua 02084
抄送: ocfs2-devel at oss.oracle.com
主题: Re: [Ocfs2-devel] Bug report and patch request reviews, thanks

On 2014/9/1 15:14, Guozhonghua wrote:
> Hi¸ we test one file which is larger than 2T, then we get the information wrong.
>
>
>
> Without patch, the result is as below, OCFS2, and you can see that size of the file and the blocks is not well:
>
>     # ls -al /vms/ocfs2lv/test_base_0
>
>     -rw------- 1 root root 2618930032640 Aug 29 19:00
> /vms/ocfs2lv/test_base_0
>
>
>
>     # stat --format="%b %B" /vms/ocfs2lv/test_base_0
>
>     820127744 512
>
>
>
>     # ls -alsi /vms/ocfs2lv/test_base_0
>
>     2100482 410063872 -rw------- 1 root root 2618930032640 Aug 29
> 19:00 /vms/ocfs2lv/test_base_0
>
>
>
>     # ls -al /vms/ocfs2lv/test_base_0
>
>     -rw------- 1 root root 2618930032640 Aug 29 19:00
> /vms/ocfs2lv/test_base_0
>
>
>
> With patch, the information of the file is correct, and the file may be have some parse space in it, so the diff of the space can be ingnored:
>
>         # stat --format "%b %B" /vms/ocfs2lv/test_base_0
>
>     5115095040 512
>
>
>
>     # ls -alsi /vms/ocfs2lv/test_base_0
>
>     2100482 2557547520 -rw------- 1 root root 2618930032640 Aug 29
> 19:00 /vms/ocfs2lv/test_base_0
>
>
>
> The patch is as below, we known that the blocks count is not correct, but we are not sure the patch has any side-effect with other part of OCFS2, so requesting reviews.
>
> Would some OCFS2 experts have time to review it and merged it into
> main line? Thanks
>
>
>
> ---  inode.h    2014-08-09 14:23:42.609594669 +0800
>
> +++ inode.h     2014-09-01 14:30:37.224294249 +0800
>
>
>
> @@ -157,7 +155,7 @@ static inline blkcnt_t
> ocfs2_inode_sector_count(struct inode *inode)
>
> {
>
>       int c_to_s_bits = OCFS2_SB(inode->i_sb)->s_clustersize_bits - 9;
>
> -       return (blkcnt_t)(OCFS2_I(inode)->ip_clusters << c_to_s_bits);
>
> +      return (blkcnt_t)((unsigned long)OCFS2_I(inode)->ip_clusters <<
> + c_to_s_bits);
>
> }

So you mean the bit operation may lead to overflow if cluster is 1MB?
Why not delete the parentheses directly?

return (blkcnt_t)OCFS2_I(inode)->ip_clusters << c_to_s_bits;
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