Re: [PATCH] pktcdvd: added sysfs interface + bio write queue handling fix

[Kay Sievers <kay.sievers@vrfy.org>]

On Sat, 2006-09-09 at 14:30 -0700, Greg KH wrote:
> On Sat, Sep 09, 2006 at 08:11:56PM +0200, Thomas Maier wrote:
> > Hello,
> > 
> > >> +    write_queue_size  (r)  Contains the size of the bio write
> > >> +                           queue.
> > ...
> > >> +    mapped_to              Symbolic link to mapped block device
> > >> +                           in the /sys/block tree.
> > >
> > > Shouldn't this whole thing be in /sys/class/ instead of /sys/block/ ?
> > 
> > Don't know. I thought, the pktcdvd is a block driver, so put
> > the control files into /sys/block ..
> > Is /sys/class better? If yes, where to put it?
> 
> Use /sys/class/pktcdvd/ and use struct device instead of struct
> class_device, so I don't have to convert the code later :)

Is this always device specific, or also driver global information? Is
pktcdvd always on a block device? Maybe you just want them to be a group
of attributes in the block device directory where they belong to, like:
  /sys/block/sr0/pktcdvd/info
  /sys/block/sr0/pktcdvd/write_queue_size
  /sys/block/sr0/pktcdvd/...

Does that make sense? We should avoid messing around with symlinks
pointing to other devices, if not absolutely needed. We should also not
create a new device type, just for adding properties to an existing one,
especially if there is not some kind of "device stacking". The
"mapped_to" link to the parent device looks like a wild hack to me, we
should avoid.

Thanks,
Kay