Re: [dm-devel] linux-next - WARNING: at fs/block_dev.c:824 bd_link_disk_holder+0x92/0x1ac()

Tejun Heo
2011-01-13T14:11:19Z

Hello,

On Thu, Jan 13, 2011 at 02:58:23PM +0100, Milan Broz wrote:
> On 01/13/2011 02:37 PM, Tejun Heo wrote:
>
> > So, just don't do it. Sysfs is for device hierarchy. Don't try to
> > shove pretty looking things there (unless it's something widely agreed
> > on and necessary, of course).
>
> I think that it is exactly what holders/slaves do - displaying device
> hierarchy. So application can check which underlying device are related
> and ask them for more info if needed (=> with system specific call,
> it can be simple sysfs attribute, ioctl, whatever).

Yeah, sure but in a completely unrestrained and non-standard way.
First of all, it wasn't even necessary to begin with and I don't
really see anyone else other than md/dm using it. I mean, where are
you gonna you put that slaves directory? Sure you can put it
somewhere but really it would be just that - somewhere. All this
doesn't even matter. It wasn't even necessary to begin with.

> So the only request here is to keep these symlinks correct, nothing more.
> Or am I missing anything?

Yeah, I'm fixing that. Don't worry. I just wanna say it wasn't such
a brilliant idea to add it in the first place and hope that people
would restrain from doing similar things in the future.

So, as a general rule, when in doubt, just create an attribute. Let's
refrain from custom symlinkery in sysfs, please. In this case too, a
holder attribute containing strings like ext[3|4], md, dm or whatnot
would have been _much_ simpler and actually more useful.

Thank you.

--
tejun