Re: Re-enable by-path links for ata device

[Robert Milasan <rmilasan@suse.cz>]

On Fri, 3 Aug 2012 10:44:11 +0200
Kay Sievers <kay@vrfy.org> wrote:

> On Thu, Aug 2, 2012 at 8:31 PM, Robert Milasan <rmilasan@suse.cz>
> wrote:
> > Hello, just created a patch for openSUSE to re-enable by-path links
> > for ata devices. The patch is based on handle_scsi_default
> > function, but instead of using "host{NUMBER}", but "ata{NUMBER}"
> > and it works almost the same as for scsi devices.
> >
> > The patch is not the best or the cleanest, but it works.
> 
> We can not play these games for any new stuff, like SCSI path_id is
> doing here, it's a legacy from a time we had we no good idea how
> things should work. What SCSI path_id is doing here is "I hope it
> works, let's try ..." software, which is a model that we don't support
> anymore. :)
> 
> We need the ATA transport class to export the local port number of the
> host adapter, and use that.
> 
> Rebasing in userspace by making assumptions about a global in-kernel
> instance counter is racy, unreliable and can only work if all things
> would always happen in strict order, and they don't. Manual driver
> unbind/bind, parallel hotplug gets into the way of this too simple
> logic.
> 
> The proper fix is to teach the kernel to export the numbers directly,
> or get the numbers in some way, but not by doing readdir() and
> starting to count and make a guess.
> 
> Hope you understand that we can not do this for any new stuff, it just
> does not meet the requirements we have today.
> 
> Thanks,
> Kay

It's fine with me, just wanted to make sure people know, maybe someone
needs it or wants it.

Thanks,
Robert