Re: [PATCH] loop: add some basic read-only sysfs attributes

[Milan Broz <mbroz@redhat.com>]

On 07/29/2010 03:47 PM, Kay Sievers wrote:
> On Thu, Jul 29, 2010 at 15:33, Milan Broz <mbroz@redhat.com> wrote:
>> Create /sys/block/loopX/loop directory and provide these attributes:
>>  - backing_file
>>  - autoclear
>>  - offset
>>  - sizelimit
>>
>> To be used in util-linux-ng (and possibly elsewhere like udev rules)
>> where code need to get loop attributes from kernel (and not store
>> duplicate info in userspace).
> 
> Isn't it that the loop attributes are created _after_ the loopdev is
> registered? That would make it hard to use these attributes from udev,
> as the event is already running while they are created.

First 8 loop devices are registered always (without backing file),
so you have wait for change event initiated from fd set ioctl anyway...
(backing file attribute is empty in that case)

Milan