Re: [Qemu-devel] [PATCH] raw-posix: improve detection of scsi-generic devices

[Bernhard Kohl]

Am 07.09.2010 04:04, schrieb ext Christoph Hellwig:
> On Mon, Sep 06, 2010 at 05:39:00PM +0200, Alexander Graf wrote:
>    
> > On 06.09.2010, at 17:06, Bernhard Kohl wrote:
> >
> >      
> > > From: Bernhard Kohl<address@hidden>
> > >
> > > Allow symbolic links which point to /dev/sgX devices.
> > >        
> > Couldn't you send an SG_IO test ioctl over and see if it works? I really 
> > dislike the whole file name magic matching.
> >      
> You could, but the result would not be what you expect, given that every
> /dev/sd* device and more in Linux support it.
>
> What we really need is to stop shoe-horning scsi pass through support
> into the block layer.  Once we finally get our generic thread offload
> facilily there is no need for it anymore at all, scsi-generic can
> simplify offload the SG_IO ioctl and be done with it.  I even have an
> old prototype for this, just waiting for the generic thread offload
> to get merged before resurrecting it.
>    

Wouldn't it be OK to apply this patch in the meantime before we get
this complete new solution? I need to handle about 15 /dev/sg* disks
which are randomly numbered. With this patch I can use the udev
generated links in /dev/disk/by*, which makes life much easier.