megaraid_sas: direct drive access for smartctl and hdparm

[Jochen Radmacher <jr@xxxxxxxxxxxxxxxxxxxxx>]

I was trying to get some useful SMART Information from the SATA drives 
connected to my PERC5/i controller, but the PERC had no options for that.
When browsing through the kernel sources I found this:

static int megasas_slave_configure(struct scsi_device *sdev)
{
        /*
         * Don't export physical disk devices to the disk driver.
         *
         * FIXME: Currently we don't export them to the midlayer at all.
         *        That will be fixed once LSI engineers have audited the
         *        firmware for possible issues.
         */
        if (sdev->channel < MEGASAS_MAX_PD_CHANNELS && sdev->type == 
TYPE_DISK)
                return -ENXIO;


I changed the if{ } to:

        if (sdev->channel < MEGASAS_MAX_PD_CHANNELS && sdev->type == 
TYPE_DISK)
        {
                sdev->writeable=1;
                sdev->no_uld_attach=1;
                return 0;
        }


This way I get sgX devices (and no extra sdX devices), which work fine 
with smartctl 5.37 and hdparm 8.4 . hdparm seems to need kernel 2.6.24 
or greater for the pass through to work.

This only is a proof of concept and I have no idea how to implement this 
correctly.
Regards,
 Jochen Radmacher
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