On Mon, Nov 12, 2012 at 9:31 AM, Paolo Bonzini <pbonz...@redhat.com> wrote:
> Il 12/11/2012 12:33, James Bottomley ha scritto:
>> On Fri, 2012-11-09 at 11:08 -0500, Jason J. Herne wrote:
>>> diff --git a/drivers/usb/storage/scsiglue.c
>>> b/drivers/usb/storage/scsiglue.c
>>> index 13b8bcd..6ff785e 100644
>>> --- a/drivers/usb/storage/scsiglue.c
>>> +++ b/drivers/usb/storage/scsiglue.c
>>> @@ -251,6 +251,11 @@ static int slave_configure(struct scsi_device
>>> *sdev)
>>> US_FL_SCM_MULT_TARG)) &&
>>> us->protocol == USB_PR_BULK)
>>> us->use_last_sector_hacks = 1;
>>> +
>>> + /* Force read-16 for large capacity drives. */
>>> + sdev->force_read_16 = 1;
>>> +
>>> +
>>
>> This turns READ_16 on unconditionally for all USB disks ... is that
>> safe? As in have you tested this with older USB thumb drives?
>
> Actually it only turns it on for large capacity drives, as said in the
> comment. sdp->force_read_16 only matters for >2TB drives:
>
I should have made this clearer. Sorry for any confusion.
> Any reason not to do this always on >2TB drives, which basically means
> changing this:
>
> - } else if (block > 0xffffffff) {
> + } else if (sdkp->capacity > 0xffffffff) {
>
> and nothing else?
This was the intent of my patch, except I wanted to *only* affect USB based
drives as my drive was functioning perfecting when connected to an internal
Sata port. I was adopting the "Do not fix what isn't broke" mentality.
If there is no reason to do otherwise, I like this suggestion. It is simple
and removes the need to provide an extra bit in the scsi_device struct.
It also eliminates the need to do any additional probe/init time checking.
We just want to be sure it won't cause problems for currently working
devices.
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