Re: [PATCH] mtd: blktrans: change blktrans_getgeo rerurn value

[Brian Norris]

On Thu, May 21, 2015 at 09:56:21AM +0200, Richard Weinberger wrote:
> On Wed, May 20, 2015 at 9:33 PM, Brian Norris
> <computersforpeace@xxxxxxxxx> wrote:
> > On Wed, May 13, 2015 at 02:29:16PM +0800, Wenlin Kang wrote:
> >> Modify function blktrans_getgeo()'s return value to -ENXIO when
> >> dev->tr->getgeo == NULL.
> >>
> >> We shouldn't make the return value to 0 when dev->tr->getgeo == NULL,
> >> because the function blktrans_getgeo() has an output value "hd_geometry"
> >> which is usually used by some application, if return 0, it will make some
> >> application get the wrong information.
> >>
> >> Signed-off-by: Wenlin Kang <wenlin.kang@xxxxxxxxxxxxx>
> >> ---
> >>  drivers/mtd/mtd_blkdevs.c |    2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
> >> index 2b0c5287..f8bb16e 100644
> >> --- a/drivers/mtd/mtd_blkdevs.c
> >> +++ b/drivers/mtd/mtd_blkdevs.c
> >> @@ -273,7 +273,7 @@ static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
> >>       if (!dev->mtd)
> >>               goto unlock;
> >>
> >> -     ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
> >> +     ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENXIO;
> >
> > Good catch. I don't think ENXIO is correct in this case, though. Maybe
> > -EOPNOTSUPP or -ENOSYS? The latter might make more sense I guess.
> 
> I'd vote for -ENOTTY as this is what HDIO_GETGEIO returns
> if the function is not implemented and blktrans_getgeo()
> is only a wrapper around that.

I suppose that makes more sense.

> See https://www.kernel.org/doc/Documentation/ioctl/hdio.txt

But this only mentions EINVAL...

> and block/ioctl.c.

Anyway, I pushed EOPNOTSUPP, but I can fix that up if we agree.

Brian
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