On Tue, 2016-03-22 at 08:14 +0100, Hannes Reinecke wrote:
> On 03/22/2016 02:16 AM, Martin K. Petersen wrote:
> >>>>>> "Hannes" == Hannes Reinecke <hare@xxxxxxx> writes:
> >
> > Hannes> in sd_read_capacity() the sdkp->capacity field changes its
> > Hannes> meaning: after the call to read_capacity_XX() it carries the
> > Hannes> _unscaled_ values, making the comparison between the original
> > Hannes> value and the new value always false for drives with a sector
> > Hannes> size != 512. So introduce a 'new_capacity' carrying the new,
> > Hannes> scaled, capacity.
> >
> > I agree with Christoph.
> >
> > How about something like this instead?
> >
> I've coded it somewhat different, but this one works as well.
> But please modify the description in sd.h, as with this patch
> 'sdkp->capacity' is the _unscaled_ value.
> Might lead to confusion otherwise.
>
> diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
> index 5f2a84a..5ed7434 100644
> --- a/drivers/scsi/sd.h
> +++ b/drivers/scsi/sd.h
> @@ -65,7 +65,7 @@ struct scsi_disk {
> struct device dev;
> struct gendisk *disk;
> atomic_t openers;
> - sector_t capacity; /* size in 512-byte sectors */
> + sector_t capacity; /* size in logical sectors */
> u32 max_xfer_blocks;
> u32 opt_xfer_blocks;
> u32 max_ws_blocks;
>
> (Apologies for the mangled patch)
>
> Cheers,
>
> Hannes
If we change the meaning of the scsi_disk->capacity field to be logical
sectors, we also have to change sd_getgeo() in sd.c, do we not?
The ->capacity field is also accessed by last_sector_hacks() in
drivers/usb/storage/transport.c, although it kind of looks like
that code might not have been correct for 4K sectors with the
scaled value.
-Ewan
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