I agree with you that the size showed in /sys/class/block/dm*/size is most accurate,
we should use this size. But I think once we showed the size of block device, we can't
guarantee that users will not use it. So I think the size of block device showed by
multipath should not greater than the real capacity. I'm looking forward to your reply.
Thanks,
Zhou
周桂春 Zhou GuiChun
软件开发 SoftWare
Development
虚拟化长沙开发部 NIV
Changsha Development Dept
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发件人: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
收件人: <zhou.guichun@xxxxxxxxxx>, Christophe Varoqui <christophe.varoqui@xxxxxxxxxxx>,
抄送: <tang.junhui@xxxxxxxxxx>, <zhang.kai16@xxxxxxxxxx>, <dm-devel@xxxxxxxxxx>
日期: 2016/10/27 02:09
主题: Re: [dm-devel] [PATCH] libmultipath: I/O access overrun occured in mutipath device under the displayed capacity
On 10/25/2016 08:18 PM, zhou.guichun@xxxxxxxxxx wrote:
> From: zhouguichun <zhou.guichun@xxxxxxxxxx>
>
> I/O access overrun occured in mutipath device under
> the displayed capacity since that the displayed
> capacity is greater than the real capacity
> (Eg. a 3456M disk display as 3.4G).
>
> In this patch, we keep the displayed capacity three
> decimals by abandoning the rest of decimals instead
> of by rounding up(Eg. a 3.4567G disk display as
> 3.456G), so that the displayed capacity will not be
> greater than the real capacity, and the error will
> also be in a permissible range.
The motivation of this patch looks really weird to me. How could the
rounding in snprint_size() cause an access past the end of a block
device? Using the output of that function as block device size is wrong.
Please use /sys/class/block/dm*/size instead.
Bart.
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