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

[Greg KH <greg@kroah.com>]

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