Re: SG_GET_ACCESS_COUNT ioctl problem

[Mark Hounschell <dmarkh@cfl.rr.com>]

> Mark,
> I think you can consider that ioctl deprecated in the
> lk 2.6 series. The implementation of that ioctl in
> lk 2.6.15 is not very encouraging:
> 
>     case SG_GET_ACCESS_COUNT:
>         /* faked - we don't have a real access count anymore */
>         val = (sdp->device ? 1 : 0);
>         return put_user(val, ip);
> 
> which will yield 1 in almost all cases. In the lk 2.6 series
> sysfs ** is meant to take over those sort of functions from
> the sg driver. However struct scsi_device (one instance per
> scsi device (normally a logical unit)) no longer seems to
> maintain an access count.
> 
> 
> I have written about the SG_IO ioctl and its various
> implementations in the lk 2.6 series at:
> http://www.torque.net/sg/sg_io.html
> 
> However I haven't addressed the status of the lesser used
> sg ioctls (e.g. SG_GET_ACCESS_COUNT) in the lk 2.6 series.
> 
> 
> ** ..._GET_ACCESS_COUNT is more of a job for procfs than
>    sysfs.
> 

So how can one safely open an sg device that happens to be a disk? I can
find no combination of open flags that will cause an open to fail if the
disk happens to be mounted? You imply this ioctl is a "lesser used"
ioctl? What 'was' the prefered method of doing this? It's the only
method I found short of writing code to xlate the sg device into an sd
device and attempting an open of that first. That's not good???

Thanks
Mark