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

[Tejun Heo <tj@kernel.org>]

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