On Wed, Apr 13, 2016 at 11:37 PM, Dave Chinner <david@fromorbit.com> wrote:

> On Wed, Apr 13, 2016 at 11:17:45AM -0500, Eric Sandeen wrote:
> > On 4/13/16 10:08 AM, Jan Tulak wrote:
> >
> > ...
> >
> > > All right​, I will keep the O_TRUNC there. However, should it
> > > truncate the file every time, or should we offer a way how to avoid
> > > the file truncating? Until now, mkfs behaved differently based on
> > > whether -d file was given, or not. Your explanation suggests that we
> > > should truncate every time, right?
> >
> > There are probably valid reasons to keep size as well as to truncate;
> > it's not immediately clear to me how we should handle it.
>
> That's easy: don't specify -dfile or -dsize, and instead let mkfs
> detect that it is file automatically. Because it's not given a size,
> or that it's supposed to be a file, it should not attempt to change
> the "device" in any way.
>
> When block devices grow fallocate support, we can unify the discard
> behaviour to be a hole punch, and then it will work identically on
> devices and files treated this way.
>
> > Honestly, at this point, in the interest of getting the other fixes in,
> > I think I might rather see the truncating behavior unchanged from what
> > we have today; we can tackle that as a separate problem at a later date.
>
> Yup, don't change it in this patch series.
>
>
Looking on this patch again, I think that it can be removed entirely. After
reverting the O_CREATE part, the only thing it does is differentiating
error messages between files and block devices, which is not worth of a
patch.

Cheers,
Jan

-- 
Jan Tulak
jtulak@redhat.com / jan@tulak.me