Re: [PATCH v9 14/15] ovl: Fix encryption/compression status of a metacopy only file

[Vivek Goyal <vgoyal@redhat.com>]

On Thu, Jan 18, 2018 at 04:32:01PM +0200, Amir Goldstein wrote:
> On Thu, Jan 18, 2018 at 4:24 PM, Vivek Goyal <vgoyal@redhat.com> wrote:
> > On Wed, Nov 29, 2017 at 10:54:47AM -0500, Vivek Goyal wrote:
> >> If file is metacopy only, it is possible that lower is encrypted while
> >> other is not. In that case, report file as encrypted (despite the fact
> >> that only data is encrypted while metadata is not).
> >>
> >> Similarly if lower is compressed, report that in stat for a metacopy
> >> only file.
> >>
> >
> > Hi Amir,
> >
> > Thinking more about this patch. Taking union of lower and upper attributes
> > (encryption and compressed) does not feel right.
> >
> > Right now if lower is compressed and upper is not (metacopy), then we will
> > report file as compressed. But if lower is not compressed while upper is,
> > still we will report file as compressed. So there is an anomaly here.
> >
> > I think, compression and encryption primarily represent the data state.
> > So always report the state from inode which has file data (lower). And
> > don't take union with upper metacopy only inode. Because state in
> > upper inode does not matter till data is copied up.
> >
> > This will also simplify my implementation when supporting metacopy in
> > middle layer. That way I don't have to do getattr() on all intermediate
> > metacopy inodes in the chain and take a union. Instead I can go to lowest
> > most data inode and take encryption and compression attributes from there.
> >
> > I am not sure why did we decide to take union of lower and upper attrs.
> > Right now it does not seem to make sense to me.
> >
> 
> Now I am not sure either. I suspect that userspace may need the ability to
> know if a file is encrypted, but I can't say for sure.
> If you want to know better ask the developers that work of fs/crypto.
> 
> I don't mind if you leave this patch out.

For now I think I prefer to leave this patch out. If somebody cares,
fixing it is really easy. Just report encryption/compression state from
the inode which actually has data.

Vivek