Re: [PATCH] btrfs: replace a wrong memset() with memzero_page()

Filipe Manana
2022-03-29T09:58:06Z

On Mon, Mar 28, 2022 at 08:51:21PM +0200, David Sterba wrote:
> On Fri, Mar 25, 2022 at 05:37:59PM +0800, Qu Wenruo wrote:
> > The original code is not really setting the memory to 0x00 but 0x01.
> >
> > To prevent such problem from happening, use memzero_page() instead.
>
> This should at least mention we think that setting it to 0 is right, as
> you call it wrong but give no hint why it's thought to be wrong.

My guess is that something different from zero makes it easier to spot
the problem in user space, as 0 is not uncommon (holes, prealloced extents)
and may get unnoticed by applications/users.

I don't see a good reason to change this behaviour. Maybe it's just the
label name 'zeroit' that makes it confusing.

>
> > Since we're here, also make @len const since it's just sectorsize.
>
> Please don't do that, adding const is fine when the line gets touched
> but otherwise adding it to an unrelated fix is not what I want to
> encourage.