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SubjectRe: [PATCH] fs: sysfs: don't pass count == 0 to bin file readers
On Fri, May 22, 2015 at 03:46:51AM +0300, Vladimir Zapolskiy wrote:
> Hello Tejun,
>
> On 22.05.2015 02:26, Tejun Heo wrote:
> > Hello, Vladimir.
> >
> > On Fri, May 22, 2015 at 02:04:31AM +0300, Vladimir Zapolskiy wrote:
> >> But "!size" is a special case,
> >>
> >> if (!count || pos >= size)
> >> return 0;
> >>
> >> seems to be incorrect in case of !size ===> (pos >= size) == true.
> >
> > Hmmm... Why is that wrong tho? If size is zero and pos is zero,
> > there's nothing to do, no?
>
> positive size value in the context means the fixed exact length of the
> file and if size == 0, then it represents some undefined size, often
> dynamic in runtime. So, if size is zero and pos is zero it stands for
> reading from the beginning of the file as many bytes as allowed by
> battr->read() realization. This special case is utilized by quite many
> bin_attribute users, probably more than half of them set .size to 0.

Ah, right, I completely forgot about that. Please feel free to add

Acked-by: Tejun Heo <tj@kernel.org>

to the original patch.

Thanks for the patience.

--
tejun


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