On 11/09/2015 03:12 PM, Karel Zak wrote:
> On Mon, Nov 09, 2015 at 02:06:26PM +0100, Florian Margaine wrote:
>> Instead of using string functions to extract the device name and reading
>> this file, this patch uses the loop device API through ioctl to get the
>> correct backing file.
> 
>     #define LO_NAME_SIZE    64
> 
>     struct loop_info64 {
>         ...
>         uint8_t         lo_file_name[LO_NAME_SIZE];
>     };
> 
> 
> The loopdev is based on file descriptor, the lo_file_name[] is hint
> only and it does not have to match with the real path and the most
> important problem is that it uses 64-bytes buffer.
> 
> For losetup we use LOOP_GET_STATUS64 ioctl as fallback solution only.

So btrfs-progs should do the same? Use the /sys filesystem by default,
and use ioctl if it doesn't find the file?

> 
>     Karel
> 
> 

-- 
Florian Margaine

Product Engineer @ Platform.sh
https://platform.sh

https://keybase.io/fmargaine