Re: sysfs question: how to map major:minor to name under /sys

From: Greg KH
Date: Thu Dec 15 2005 - 22:18:30 EST


On Thu, Dec 15, 2005 at 02:14:06PM +1100, Neil Brown wrote:
>
> Hi,
> I have a question about sysfs related usage.
>
> Suppose I have a major:minor number for a block device - maybe from
> fstat of a filedescriptor I was given, or stat of a name in /dev.
> How do I find the directory in /sys/block that contains relevant
> information?
>
> It seems to me that there is no direct way, and maybe there should
> be. (I can do a find of 'dev' file and compare, which is fine in a
> one-off shell script, but sub-optimal in general).

So you want this info from userspace, not from within the kernel, right?

> The most obvious solution would be to have a directory somewhere full
> of symlinks:
> /sys/block_dev/8:0 -> ../block/sda
> or whatever.
> Is this reasonable? Should I try it?

It seems a bit md specific to add a lot of kernel code for something
that can be solved with a userspace shell script :)

But if you want to try it, use a class, and a class_device for this, not
raw kobjects. It should be a bit easier that way.

thanks,

greg k-h
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